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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html><head><title>C++ Standard Library Active Issues List</title>



<style type="text/css">
p {text-align:justify}
li {text-align:justify}
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del {background-color:#FFA0A0}
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<table>
<tbody><tr>
<td align="left">Doc. no.</td>
<td align="left">N2456=07-0326</td>
</tr>
<tr>
<td align="left">Date:</td>
<td align="left">2007-10-20</td>
</tr>
<tr>
<td align="left">Project:</td>
<td align="left">Programming Language C++</td>
</tr>
<tr>
<td align="left">Reply to:</td>
<td align="left">Howard Hinnant &lt;<a href="mailto:howard.hinnant@gmail.com">howard.hinnant@gmail.com</a>&gt;</td>
</tr>
</tbody></table>
<h1>C++ Standard Library Active Issues List (Revision R52)</h1>

  <p>Reference ISO/IEC IS 14882:1998(E)</p>
  <p>Also see:</p>
  <ul>
      <li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-toc.html">Table of Contents</a> for all library issues.</li>
      <li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html">Index by Section</a> for all library issues.</li>
      <li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html">Index by Status</a> for all library issues.</li>
      <li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html">Library Defect Reports List</a></li>
      <li><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html">Library Closed Issues List</a></li>
  </ul>
  <p>The purpose of this document is to record the status of issues
  which have come before the Library Working Group (LWG) of the ANSI
  (J16) and ISO (WG21) C++ Standards Committee. Issues represent
  potential defects in the ISO/IEC IS 14882:1998(E) document.  Issues
  are not to be used to request new features. </p>

  <p>This document contains only library issues which are actively being
  considered by the Library Working Group. That is, issues which have a
  status of <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>, 
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>, and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>. See
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html">Library Defect Reports List</a> for issues considered defects and 
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html">Library Closed Issues List</a> for issues considered closed.</p>

  <p>The issues in these lists are not necessarily formal ISO Defect
  Reports (DR's). While some issues will eventually be elevated to
  official Defect Report status, other issues will be disposed of in
  other ways. See <a href="#Status">Issue Status</a>.</p>

  <p>This document is in an experimental format designed for both
  viewing via a world-wide web browser and hard-copy printing. It
  is available as an HTML file for browsing or PDF file for
  printing.</p>

  <p>Prior to Revision 14, library issues lists existed in two slightly
  different versions; a Committee Version and a Public
  Version. Beginning with Revision 14 the two versions were combined
  into a single version.</p>

  <p>This document includes <i>[bracketed italicized notes]</i> as a
  reminder to the LWG of current progress on issues. Such notes are
  strictly unofficial and should be read with caution as they may be
  incomplete or incorrect. Be aware that LWG support for a particular
  resolution can quickly change if new viewpoints or killer examples are
  presented in subsequent discussions.</p>

  <p>For the most current official version of this document see 
  <a href="http://www.open-std.org/jtc1/sc22/wg21/">http://www.open-std.org/jtc1/sc22/wg21/</a>.
  Requests for further information about this document should include
  the document number above, reference ISO/IEC 14882:1998(E), and be
  submitted to Information Technology Industry Council (ITI), 1250 Eye
  Street NW, Washington, DC 20005.</p>

  <p>Public information as to how to obtain a copy of the C++ Standard,
  join the standards committee, submit an issue, or comment on an issue
  can be found in the comp.std.c++ FAQ.
  Public discussion of C++ Standard related issues occurs on <a href="news:comp.std.c++">news:comp.std.c++</a>.
  </p>

 <p>For committee members, files available on the committee's private
  web site include the HTML version of the Standard itself. HTML
  hyperlinks from this issues list to those files will only work for
  committee members who have downloaded them into the same disk
  directory as the issues list files.  </p>

<h2>Revision History</h2>
<ul>
<li>R52: 
2007-10-19 post-Kona mailing.
<ul>
<li><b>Summary:</b><ul>
<li>172 open issues, up by 4.</li>
<li>582 closed issues, up by 27.</li>
<li>754 issues total, up by 31.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added the following New issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#724">724</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#725">725</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#726">726</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#727">727</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#728">728</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#729">729</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#730">730</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#731">731</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#732">732</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#733">733</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#734">734</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#735">735</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#736">736</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#737">737</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#738">738</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#739">739</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#740">740</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#741">741</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#742">742</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#743">743</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#744">744</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#745">745</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#746">746</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#747">747</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#748">748</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#749">749</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#750">750</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#751">751</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#752">752</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#753">753</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#754">754</a>.</li>
<li>Changed the following issues from NAD Future to Dup: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#77">77</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#350">350</a>.</li>
<li>Changed the following issues from New to NAD: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#639">639</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#657">657</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#663">663</a>.</li>
<li>Changed the following issues from Open to NAD: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#548">548</a>.</li>
<li>Changed the following issues from New to Open: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#546">546</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#550">550</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#564">564</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#565">565</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#573">573</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#585">585</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#588">588</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#627">627</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#629">629</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#630">630</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#632">632</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#635">635</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#653">653</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#659">659</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#667">667</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#668">668</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#669">669</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#670">670</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#671">671</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#673">673</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#686">686</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#704">704</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#707">707</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#708">708</a>.</li>
<li>Changed the following issues from New to Pending NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#393">393</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#592">592</a>.</li>
<li>Changed the following issues from New to Pending WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#607">607</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#608">608</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#654">654</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#655">655</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#677">677</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#682">682</a>.</li>
<li>Changed the following issues from New to Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#561">561</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#562">562</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#563">563</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#567">567</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#581">581</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#595">595</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#620">620</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#621">621</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#622">622</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#623">623</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#624">624</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#661">661</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#664">664</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#665">665</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#666">666</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#674">674</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#675">675</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#676">676</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#679">679</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#687">687</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#688">688</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#689">689</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#693">693</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#694">694</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#695">695</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#700">700</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#703">703</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#705">705</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#706">706</a>.</li>
<li>Changed the following issues from Open to Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#680">680</a>.</li>
<li>Changed the following issues from New to Review: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#574">574</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#596">596</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#618">618</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#638">638</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#645">645</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#672">672</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#684">684</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#685">685</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#691">691</a>.</li>
<li>Changed the following issues from New to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#552">552</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#634">634</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#650">650</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#651">651</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#652">652</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#678">678</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#681">681</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#699">699</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#712">712</a>.</li>
<li>Changed the following issues from Open to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#258">258</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#401">401</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#524">524</a>.</li>
<li>Changed the following issues from Ready to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#488">488</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#577">577</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#660">660</a>.</li>
</ul></li>
</ul>
</li>
<li>R51: 
2007-09-09 pre-Kona mailing.
<ul>
<li><b>Summary:</b><ul>
<li>168 open issues, up by 15.</li>
<li>555 closed issues, up by 0.</li>
<li>723 issues total, up by 15.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added the following New issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#709">709</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#710">710</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#711">711</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#712">712</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#713">713</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#714">714</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#715">715</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#716">716</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#717">717</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#718">718</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#719">719</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#720">720</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#721">721</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#722">722</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#723">723</a>.</li>
</ul></li>
</ul>
</li>
<li>R50: 
2007-08-05 post-Toronto mailing.
<ul>
<li><b>Summary:</b><ul>
<li>153 open issues, down by 5.</li>
<li>555 closed issues, up by 17.</li>
<li>708 issues total, up by 12.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added the following New issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#697">697</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#698">698</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#699">699</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#700">700</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#701">701</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#702">702</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#703">703</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#704">704</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#705">705</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#706">706</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#707">707</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#708">708</a>.</li>
<li>Changed the following issues from New to NAD: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#583">583</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#584">584</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#662">662</a>.</li>
<li>Changed the following issues from Open to NAD: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#528">528</a>.</li>
<li>Changed the following issues from New to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#637">637</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#647">647</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#658">658</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#690">690</a>.</li>
<li>Changed the following issues from Open to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#525">525</a>.</li>
<li>Changed the following issues from Pending NAD Editorial to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#553">553</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#571">571</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#591">591</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#633">633</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#636">636</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#641">641</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#642">642</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#648">648</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#649">649</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#656">656</a>.</li>
<li>Changed the following issues from New to Open: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#579">579</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#631">631</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#680">680</a>.</li>
<li>Changed the following issues from Pending WP to Open: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#258">258</a>.</li>
<li>Changed the following issues from Ready to Pending WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#644">644</a>.</li>
<li>Changed the following issues from New to Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#577">577</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#660">660</a>.</li>
<li>Changed the following issues from Open to Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#488">488</a>.</li>
<li>Changed the following issues from Open to Review: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#518">518</a>.</li>
<li>Changed the following issues from Ready to TRDec: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#604">604</a>.</li>
<li>Changed the following issues from DR to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#453">453</a>.</li>
<li>Changed the following issues from Ready to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#531">531</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#551">551</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#566">566</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#628">628</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#640">640</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#643">643</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#646">646</a>.</li>
</ul></li>
</ul>
</li>
<li>R49: 
2007-06-23 pre-Toronto mailing.
<ul>
<li><b>Summary:</b><ul>
<li>158 open issues, up by 13.</li>
<li>538 closed issues, up by 7.</li>
<li>696 issues total, up by 20.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added the following New issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#677">677</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#678">678</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#679">679</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#680">680</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#681">681</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#682">682</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#684">684</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#685">685</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#686">686</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#687">687</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#688">688</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#689">689</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#690">690</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#691">691</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#692">692</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#693">693</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#694">694</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#695">695</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#696">696</a>.</li>
<li>Added the following Pending NAD Editorial issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#683">683</a>.</li>
<li>Changed the following issues from New to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#587">587</a>.</li>
<li>Changed the following issues from Open to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#590">590</a>.</li>
<li>Changed the following issues from New to Pending NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#636">636</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#642">642</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#648">648</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#649">649</a>.</li>
</ul></li>
</ul>
</li>
<li>R48: 
2007-05-06 post-Oxford mailing.
<ul>
<li><b>Summary:</b><ul>
<li>145 open issues, down by 33.</li>
<li>531 closed issues, up by 53.</li>
<li>676 issues total, up by 20.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added the following New issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#657">657</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#658">658</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#659">659</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#660">660</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#661">661</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#662">662</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#663">663</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#664">664</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#665">665</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#666">666</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#667">667</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#668">668</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#669">669</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#670">670</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#671">671</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#672">672</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#673">673</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#674">674</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#675">675</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#676">676</a>.</li>
<li>Changed the following issues from Tentatively Ready to Dup: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#479">479</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#536">536</a>.</li>
<li>Changed the following issues from Tentatively Ready to NAD: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#385">385</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#463">463</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#466">466</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#470">470</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#515">515</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#526">526</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#547">547</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#560">560</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#572">572</a>.</li>
<li>Changed the following issues from NAD to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#351">351</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#357">357</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#368">368</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#499">499</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#513">513</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#514">514</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#516">516</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#544">544</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#549">549</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#555">555</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#558">558</a>.</li>
<li>Changed the following issues from Tentatively Ready to NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#482">482</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#615">615</a>.</li>
<li>Changed the following issues from NAD_Future to NAD Future: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#77">77</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#105">105</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#111">111</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#116">116</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#128">128</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#138">138</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#140">140</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#149">149</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#180">180</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#188">188</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#190">190</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#219">219</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#323">323</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#348">348</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#350">350</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#353">353</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#388">388</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#390">390</a>.</li>
<li>Changed the following issues from Tentatively Ready to Open: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#471">471</a>.</li>
<li>Changed the following issues from New to Pending NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#633">633</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#641">641</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#656">656</a>.</li>
<li>Changed the following issues from Tentatively Ready to Pending NAD Editorial: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#532">532</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#553">553</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#571">571</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#591">591</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#594">594</a>.</li>
<li>Changed the following issues from Tentatively Ready to Pending WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#258">258</a>.</li>
<li>Changed the following issues from New to Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#566">566</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#628">628</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#640">640</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#643">643</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#644">644</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#646">646</a>.</li>
<li>Changed the following issues from Review to Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#531">531</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#551">551</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#604">604</a>.</li>
<li>Changed the following issues from Ready to TRDec: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#598">598</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#599">599</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#600">600</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#601">601</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#602">602</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#603">603</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#605">605</a>.</li>
<li>Changed the following issues from Ready to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#543">543</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#545">545</a>.</li>
<li>Changed the following issues from Tentatively Ready to WP: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#201">201</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#206">206</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#233">233</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#254">254</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#416">416</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#422">422</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#456">456</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#534">534</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#542">542</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#559">559</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#575">575</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#576">576</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#578">578</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#586">586</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#589">589</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#593">593</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#609">609</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#610">610</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#611">611</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#613">613</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#616">616</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#619">619</a>.</li>
</ul></li>
</ul>
</li>
<li>R47: 
2007-03-09 pre-Oxford mailing.
<ul>
<li><b>Summary:</b><ul>
<li>178 open issues, up by 37.</li>
<li>478 closed issues, up by 0.</li>
<li>656 issues total, up by 37.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added the following New issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#620">620</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#621">621</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#622">622</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#623">623</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#624">624</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#627">627</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#628">628</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#629">629</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#630">630</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#631">631</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#632">632</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#633">633</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#634">634</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#635">635</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#636">636</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#637">637</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#638">638</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#639">639</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#640">640</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#641">641</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#642">642</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#643">643</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#644">644</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#645">645</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#646">646</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#647">647</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#648">648</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#649">649</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#650">650</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#651">651</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#652">652</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#653">653</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#654">654</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#655">655</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#656">656</a>.</li>
<li>Added the following Open issues: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#625">625</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#626">626</a>.</li>
<li>Changed the following issues from New to Open: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#570">570</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#580">580</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#582">582</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#590">590</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#612">612</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#614">614</a>.</li>
<li>Changed the following issues from New to Tentatively Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#547">547</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#553">553</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#560">560</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#571">571</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#572">572</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#575">575</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#576">576</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#578">578</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#586">586</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#589">589</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#591">591</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#593">593</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#594">594</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#609">609</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#610">610</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#611">611</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#613">613</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#615">615</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#616">616</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#619">619</a>.</li>
<li>Changed the following issues from Open to Tentatively Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#201">201</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#206">206</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#233">233</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#254">254</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#258">258</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#385">385</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#416">416</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#422">422</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#456">456</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#463">463</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#466">466</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#470">470</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#471">471</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#479">479</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#482">482</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#515">515</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#526">526</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#532">532</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#536">536</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#542">542</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#559">559</a>.</li>
<li>Changed the following issues from Review to Tentatively Ready: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#534">534</a>.</li>
</ul></li>
</ul>
</li>
<li>R46: 
2007-01-12 mid-term mailing.
<ul>
<li><b>Summary:</b><ul>
<li>141 open issues, up by 11.</li>
<li>478 closed issues, down by 1.</li>
<li>619 issues total, up by 10.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#610">610</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#619">619</a>.</li>
</ul></li>
</ul>
</li>
<li>R45: 
2006-11-03 post-Portland mailing.
<ul>
<li><b>Summary:</b><ul>
<li>130 open issues, up by 0.</li>
<li>479 closed issues, up by 17.</li>
<li>609 issues total, up by 17.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#520">520</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#521">521</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#530">530</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#535">535</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#537">537</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#538">538</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#540">540</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#541">541</a> to WP.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#516">516</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#544">544</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#549">549</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#554">554</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#555">555</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#558">558</a> to NAD.</li>
<li>Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#569">569</a> to Dup.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#518">518</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#523">523</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#524">524</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#542">542</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#556">556</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#557">557</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#559">559</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#597">597</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#606">606</a> to Open.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#543">543</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#545">545</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#549">549</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#549">549</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#598">598</a> - <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#603">603</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#605">605</a> to Ready.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#531">531</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#551">551</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#604">604</a> to Review.</li>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#593">593</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#609">609</a>.</li>
</ul></li>
</ul>
</li>
<li>R44: 
2006-09-08 pre-Portland mailing.
<ul>
<li><b>Summary:</b><ul>
<li>130 open issues, up by 6.</li>
<li>462 closed issues, down by 1.</li>
<li>592 issues total, up by 5.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#583">583</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#592">592</a>.</li>
</ul></li>
</ul>
</li>
<li>R43: 
2006-06-23 mid-term mailing.
<ul>
<li><b>Summary:</b><ul>
<li>124 open issues, up by 14.</li>
<li>463 closed issues, down by 1.</li>
<li>587 issues total, up by 13.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#575">575</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#582">582</a>.</li>
<li>Reopened <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#255">255</a>.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#520">520</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#541">541</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#544">544</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#569">569</a> to Tentatively Ready.</li>
</ul></li>
</ul>
</li>
<li>R42: 
2006-04-21 post-Berlin mailing.
<ul>
<li><b>Summary:</b><ul>
<li>110 open issues, down by 16.</li>
<li>464 closed issues, up by 24.</li>
<li>574 issues total, up by 8.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#567">567</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#572">572</a>.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#499">499</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#501">501</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#506">506</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#509">509</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#511">511</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#513">513</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#514">514</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#517">517</a> to NAD.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#502">502</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#503">503</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#515">515</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#516">516</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#522">522</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#525">525</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#529">529</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#532">532</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#536">536</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#539">539</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#548">548</a> to Open.</li>
<li>Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#521">521</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#530">530</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#531">531</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#535">535</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#537">537</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#538">538</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#540">540</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#549">549</a> to Ready.</li>
<li>Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#247">247</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#294">294</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#362">362</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#369">369</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#371">371</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#376">376</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#384">384</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#475">475</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#478">478</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#495">495</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#497">497</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#505">505</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#507">507</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#508">508</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#519">519</a> to WP.</li>
<li>Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#534">534</a> to Review.</li>
</ul></li>
</ul>
</li>
<li>R41: 
2006-02-24 pre-Berlin mailing.
<ul>
<li><b>Summary:</b><ul>
<li>126 open issues, up by 31.</li>
<li>440 closed issues, up by 0.</li>
<li>566 issues total, up by 31.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#536">536</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#566">566</a>.</li>
<li>Moved <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#342">342</a> from Ready to Open.</li>
<li>Reopened <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#309">309</a>.</li>
</ul></li>
</ul>
</li>
<li>R40: 
2005-12-16 mid-term mailing.
<ul>
<li><b>Summary:</b><ul>
<li>95 open issues.</li>
<li>440 closed issues.</li>
<li>535 issues total.</li>
</ul></li>
<li><b>Details:</b><ul>
<li>Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#529">529</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#535">535</a>.</li>
</ul></li>
</ul>
</li>
<li>R39: 
2005-10-14 post-Mont Tremblant mailing.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#526">526</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#528">528</a>.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#280">280</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#461">461</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#464">464</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#465">465</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#467">467</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#468">468</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#474">474</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#496">496</a> from Ready to WP as per the vote from Mont Tremblant.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#247">247</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#294">294</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#342">342</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#362">362</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#369">369</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#371">371</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#376">376</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#384">384</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#475">475</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#478">478</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#495">495</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#497">497</a> from Review to Ready.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#498">498</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#504">504</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#506">506</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#509">509</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#510">510</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#511">511</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#512">512</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#513">513</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#514">514</a> from New to Open.
Moved issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#505">505</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#507">507</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#508">508</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#519">519</a> from New to Ready.
Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#500">500</a> from New to NAD.
Moved issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#518">518</a> from New to Review.
</li>
<li>R38: 
2005-07-03 pre-Mont Tremblant mailing.
Merged open TR1 issues in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#504">504</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#522">522</a>.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#523">523</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#523">523</a>
</li>
<li>R37: 
2005-06 mid-term mailing.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#498">498</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#503">503</a>.
</li>
<li>R36: 
2005-04 post-Lillehammer mailing. All issues in "ready" status except
for <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#454">454</a> were moved to "DR" status, and all issues
previously in "DR" status were moved to "WP".
</li>
<li>R35: 
2005-03 pre-Lillehammer mailing.
</li>
<li>R34: 
2005-01 mid-term mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#488">488</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#494">494</a>.
</li>
<li>R33: 
2004-11 post-Redmond mailing. Reflects actions taken in Redmond.
</li>
<li>R32: 
2004-09 pre-Redmond mailing: reflects new proposed resolutions and
new issues received after the 2004-07 mailing.  Added
new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#479">479</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#481">481</a>.
</li>
<li>R31: 
2004-07 mid-term mailing: reflects new proposed resolutions and
new issues received after the post-Sydney mailing.  Added
new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#463">463</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#478">478</a>.
</li>
<li>R30: 
Post-Sydney mailing: reflects decisions made at the Sydney meeting.
Voted all "Ready" issues from R29 into the working paper.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#460">460</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#462">462</a>.
</li>
<li>R29: 
Pre-Sydney mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#441">441</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#457">457</a>.
</li>
<li>R28: 
Post-Kona mailing: reflects decisions made at the Kona meeting.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#432">432</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#440">440</a>.
</li>
<li>R27: 
Pre-Kona mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#404">404</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#431">431</a>.
</li>
<li>R26: 
Post-Oxford mailing: reflects decisions made at the Oxford meeting.
All issues in Ready status were voted into DR status.  All issues in
DR status were voted into WP status.
</li>
<li>R25: 
Pre-Oxford mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#390">390</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#402">402</a>.
</li>
<li>R24: 
Post-Santa Cruz mailing: reflects decisions made at the Santa Cruz
meeting.  All Ready issues from R23 with the exception of <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#253">253</a>, which has been given a new proposed resolution, were
moved to DR status.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#383">383</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#389">389</a>.  (Issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#387">387</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#389">389</a> were discussed
at the meeting.)  Made progress on issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#225">225</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#226">226</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#229">229</a>: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#225">225</a> and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#229">229</a> have been moved to Ready status, and the only remaining
concerns with <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#226">226</a> involve wording.
</li>
<li>R23: 
Pre-Santa Cruz mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#367">367</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#382">382</a>.
Moved issues in the TC to TC status.
</li>
<li>R22: 
Post-Curaçao mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#362">362</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#366">366</a>.
</li>
<li>R21: 
Pre-Curaçao mailing.  Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#351">351</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#361">361</a>.
</li>
<li>R20: 
Post-Redmond mailing; reflects actions taken in Redmond.  Added
new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#336">336</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#350">350</a>, of which issues 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#347">347</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#350">350</a> were added since Redmond, hence
not discussed at the meeting.  

All Ready issues were moved to DR status, with the exception of issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#284">284</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#241">241</a>, and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#267">267</a>.

Noteworthy issues discussed at Redmond include 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#120">120</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#202">202</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#226">226</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#233">233</a>, 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#270">270</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#253">253</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#254">254</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#323">323</a>.
</li>
<li>R19: 
Pre-Redmond mailing.  Added new issues 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#323">323</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#335">335</a>.
</li>
<li>R18: 
Post-Copenhagen mailing; reflects actions taken in Copenhagen.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#312">312</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#317">317</a>, and discussed
new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#271">271</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#314">314</a>.

Changed status of issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#103">103</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#118">118</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#136">136</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#153">153</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#165">165</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#171">171</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#183">183</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#184">184</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#185">185</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#186">186</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#214">214</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#221">221</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#234">234</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#237">237</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#243">243</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#248">248</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#251">251</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#252">252</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#256">256</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#260">260</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#261">261</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#262">262</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#263">263</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#265">265</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#268">268</a>
to DR.

Changed status of issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#49">49</a>  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#109">109</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#117">117</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#182">182</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#228">228</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#230">230</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#232">232</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#235">235</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#238">238</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#241">241</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#242">242</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#250">250</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#259">259</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#264">264</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#266">266</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#267">267</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#271">271</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#272">272</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#273">273</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#275">275</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#281">281</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#284">284</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#285">285</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#286">286</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#288">288</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#292">292</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#295">295</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#297">297</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#298">298</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#301">301</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#303">303</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#306">306</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#307">307</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#308">308</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#312">312</a>
to Ready.

Closed issues 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#111">111</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#277">277</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#279">279</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#287">287</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#289">289</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#293">293</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#302">302</a> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#313">313</a>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#314">314</a>
as NAD.

</li>
<li>R17: 
Pre-Copenhagen mailing.  Converted issues list to XML.  Added proposed
resolutions for issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#49">49</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#76">76</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#91">91</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#235">235</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#250">250</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#267">267</a>.
Added new issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#278">278</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#311">311</a>.
</li>
<li>R16:  
post-Toronto mailing; reflects actions taken in Toronto. Added new
issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#265">265</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#277">277</a>.  Changed status of issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#3">3</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#8">8</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#9">9</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#19">19</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#26">26</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#31">31</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#61">61</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#63">63</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#86">86</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#108">108</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#112">112</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#114">114</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#115">115</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#122">122</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#127">127</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#129">129</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#134">134</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#137">137</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#142">142</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#144">144</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#146">146</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#147">147</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#159">159</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#164">164</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#170">170</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#181">181</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#199">199</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#208">208</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#209">209</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#210">210</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#211">211</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#212">212</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#217">217</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#220">220</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#222">222</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#223">223</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#224">224</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#227">227</a> to "DR".  Reopened issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#23">23</a>. Reopened
issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#187">187</a>. Changed issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#2">2</a> and
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#4">4</a> to NAD. Fixed a typo in issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#17">17</a>. Fixed
issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#70">70</a>: signature should be changed both places it
appears. Fixed issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#160">160</a>: previous version didn't fix
the bug in enough places.
</li>
<li>R15: 
pre-Toronto mailing. Added issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#233">233</a>-<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#264">264</a>. Some small HTML formatting
changes so that we pass Weblint tests.
</li>
<li>R14: 
post-Tokyo II mailing; reflects committee actions taken in
Tokyo. Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#228">228</a> to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#232">232</a>. (00-0019R1/N1242)
</li>
<li>R13: 
pre-Tokyo II updated: Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#212">212</a> to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#227">227</a>.
</li>
<li>R12: 
pre-Tokyo II mailing: Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#199">199</a> to
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#211">211</a>. Added "and paragraph 5" to the proposed resolution
of issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#29">29</a>.  Add further rationale to issue
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#178">178</a>.
</li>
<li>R11: 
post-Kona mailing: Updated to reflect LWG and full committee actions
in Kona (99-0048/N1224). Note changed resolution of issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#4">4</a> and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#38">38</a>. Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#196">196</a>
to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#198">198</a>. Closed issues list split into "defects" and
"closed" documents.  Changed the proposed resolution of issue
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#4">4</a> to NAD, and changed the wording of proposed resolution
of issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#38">38</a>.
</li>
<li>R10: 
pre-Kona updated.  Added proposed resolutions <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#83">83</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#86">86</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#91">91</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#92">92</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#109">109</a>. Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#190">190</a> to
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#195">195</a>. (99-0033/D1209, 14 Oct 99)
</li>
<li>R9: 
pre-Kona mailing.  Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#140">140</a> to
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#189">189</a>. Issues list split into separate "active" and
"closed" documents. (99-0030/N1206, 25 Aug 99)
</li>
<li>R8: 
post-Dublin mailing. Updated to reflect LWG and full committee actions
in Dublin. (99-0016/N1193, 21 Apr 99)
</li>
<li>R7: 
pre-Dublin updated: Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#130">130</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#131">131</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#132">132</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#133">133</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#134">134</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#135">135</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#136">136</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#137">137</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#138">138</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#139">139</a> (31 Mar 99)
</li>
<li>R6: 
pre-Dublin mailing. Added issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#127">127</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#128">128</a>,
and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#129">129</a>.  (99-0007/N1194, 22 Feb 99)
</li>
<li>R5: 
update issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#103">103</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#112">112</a>; added issues
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#114">114</a> to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#126">126</a>. Format revisions to prepare
for making list public. (30 Dec 98)
</li>
<li>R4: 
post-Santa Cruz II updated: Issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#110">110</a>,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#111">111</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#112">112</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#113">113</a> added, several
issues corrected. (22 Oct 98)
</li>
<li>R3: 
post-Santa Cruz II: Issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#94">94</a> to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#109">109</a>
added, many issues updated to reflect LWG consensus (12 Oct 98)
</li>
<li>R2: 
pre-Santa Cruz II: Issues <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#73">73</a> to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#93">93</a> added,
issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#17">17</a> updated. (29 Sep 98)
</li>
<li>R1: 
Correction to issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#55">55</a> resolution, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#60">60</a> code
format, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#64">64</a> title. (17 Sep 98)
</li>
</ul>

<h2><a name="Status"></a>Issue Status</h2>

  <p><b><a name="New">New</a></b> - The issue has not yet been
  reviewed by the LWG. Any <b>Proposed Resolution</b> is purely a
  suggestion from the issue submitter, and should not be construed as
  the view of LWG.</p>

  <p><b><a name="Open">Open</a></b> - The LWG has discussed the issue
  but is not yet ready to move the issue forward. There are several
  possible reasons for open status:</p>
     <ul>
        <li>Consensus may have not yet have been reached as to how to deal
            with the issue.</li>
        <li>Informal consensus may have been reached, but the LWG awaits
            exact <b>Proposed Resolution</b> wording for review.</li>
        <li>The LWG wishes to consult additional technical experts before
            proceeding.</li>
        <li>The issue may require further study.</li>
     </ul>

  <p>A <b>Proposed Resolution</b> for an open issue is still not be
  construed as the view of LWG. Comments on the current state of
  discussions are often given at the end of open issues in an italic
  font. Such comments are for information only and should not be given
  undue importance.</p>

  <p><b><a name="Dup">Dup</a></b> - The LWG has reached consensus that
  the issue is a duplicate of another issue, and will not be further
  dealt with. A <b>Rationale</b> identifies the duplicated issue's
  issue number.  </p>

  <p><b><a name="NAD">NAD</a></b> - The LWG has reached consensus that
  the issue is not a defect in the Standard.</p>

  <p><b><a name="NAD Editorial">NAD Editorial</a></b> - The LWG has reached consensus that
  the issue can either be handled editorially, or is handled by a paper (usually
  linked to in the rationale).</p>

  <p><b><a name="NAD Future">NAD Future</a></b> - In addition to the regular
  status, the LWG believes that this issue should be revisited at the
  next revision of the standard.</p>

  <p><b><a name="Review">Review</a></b> - Exact wording of a
  <b>Proposed Resolution</b> is now available for review on an issue
  for which the LWG previously reached informal consensus.</p>

  <p><b><a name="Tentatively Ready">Tentatively Ready</a></b> - The issue has
  been reviewed online, but not in a meeting, and some support has been formed
  for the proposed resolution.  Tentatively Ready issues may be moved to Ready
  and forwarded to full committee within the same meeting.  Unlike Ready issues
  they will be reviewed in subcommittee prior to forwarding to full committee.</p>

  <p><b><a name="Ready">Ready</a></b> - The LWG has reached consensus
  that the issue is a defect in the Standard, the <b>Proposed
  Resolution</b> is correct, and the issue is ready to forward to the
  full committee for further action as a Defect Report (DR).</p>

  <p><b><a name="DR">DR</a></b> - (Defect Report) - The full J16
  committee has voted to forward the issue to the Project Editor to be
  processed as a Potential Defect Report. The Project Editor reviews
  the issue, and then forwards it to the WG21 Convenor, who returns it
  to the full committee for final disposition. This issues list
  accords the status of DR to all these Defect Reports regardless of
  where they are in that process.</p>

  <p><b><a name="TC">TC</a></b> - (Technical Corrigenda) - The full
  WG21 committee has voted to accept the Defect Report's Proposed
  Resolution as a Technical Corrigenda.  Action on this issue is thus
  complete and no further action is possible under ISO rules.</p>

  <p><b><a name="TRDec">TRDec</a></b> - (Decimal TR defect) - The 
  LWG has voted to accept the Defect Report's Proposed
  Resolution into the Decimal TR.  Action on this issue is thus
  complete and no further action is expected.</p>

  <p><b><a name="WP">WP</a></b> - (Working Paper) - The proposed
  resolution has not been accepted as a Technical Corrigendum, but
  the full WG21 committee has voted to apply the Defect Report's Proposed
  Resolution to the working paper.</p>

  <p><b>Pending</b> - This is a <i>status qualifier</i>.  When prepended to
  a status this indicates the issue has been
  processed by the committee, and a decision has been made to move the issue to
  the associated unqualified status.  However for logistical reasons the indicated
  outcome of the issue has not yet appeared in the latest working paper.

  </p><p>Issues are always given the status of <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a> when
  they first appear on the issues list. They may progress to
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a> or <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a> while the LWG
  is actively working on them. When the LWG has reached consensus on
  the disposition of an issue, the status will then change to
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Dup">Dup</a>, <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#NAD">NAD</a>, or
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a> as appropriate.  Once the full J16 committee votes to
  forward Ready issues to the Project Editor, they are given the
  status of Defect Report ( <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#DR">DR</a>). These in turn may
  become the basis for Technical Corrigenda (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#TC">TC</a>),
  or are closed without action other than a Record of Response
  (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#RR">RR</a> ). The intent of this LWG process is that
  only issues which are truly defects in the Standard move to the
  formal ISO DR status.
  </p>


<h2>Active Issues</h2>
<hr>
<h3><a name="23"></a>23. Num_get overflow result</h3>
<p><b>Section:</b> 22.2.2.1.2 [facet.num.get.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Nathan Myers <b>Date:</b> 1998-08-06</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#facet.num.get.virtuals">active issues</a> in [facet.num.get.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#facet.num.get.virtuals">issues</a> in [facet.num.get.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>The current description of numeric input does not account for the
possibility of overflow. This is an implicit result of changing the
description to rely on the definition of scanf() (which fails to
report overflow), and conflicts with the documented behavior of
traditional and current implementations. </p>

<p>Users expect, when reading a character sequence that results in a
value unrepresentable in the specified type, to have an error
reported. The standard as written does not permit this. </p>

<p><b>Further comments from Dietmar:</b></p>

<p>
I don't feel comfortable with the proposed resolution to issue 23: It
kind of simplifies the issue to much. Here is what is going on:
</p>

<p>
Currently, the behavior of numeric overflow is rather counter intuitive
and hard to trace, so I will describe it briefly:
</p>

<ul>
  <li>
    According to 22.2.2.1.2 [facet.num.get.virtuals]
    paragraph 11 <tt>failbit</tt> is set if <tt>scanf()</tt> would
    return an input error; otherwise a value is converted to the rules
    of <tt>scanf</tt>.
  </li>
  <li> 
    <tt>scanf()</tt> is defined in terms of <tt>fscanf()</tt>. 
  </li>
  <li>
    <tt>fscanf()</tt> returns an input failure if during conversion no
    character matching the conversion specification could be extracted
    before reaching EOF. This is the only reason for <tt>fscanf()</tt>
    to fail due to an input error and clearly does not apply to the case
    of overflow.
  </li>
  <li>
    Thus, the conversion is performed according to the rules of
    <tt>fscanf()</tt> which basically says that <tt>strtod</tt>,
    <tt>strtol()</tt>, etc. are to be used for the conversion.
  </li>
  <li>
    The <tt>strtod()</tt>, <tt>strtol()</tt>, etc. functions consume as
    many matching characters as there are and on overflow continue to
    consume matching characters but also return a value identical to
    the maximum (or minimum for signed types if there was a leading minus)
    value of the corresponding type and set <tt>errno</tt> to <tt>ERANGE</tt>.
  </li>
  <li>
    Thus, according to the current wording in the standard, overflows
    can be detected! All what is to be done is to check <tt>errno</tt>
    after reading an element and, of course, clearing <tt>errno</tt>
    before trying a conversion. With the current wording, it can be
    detected whether the overflow was due to a positive or negative
    number for signed types.
  </li>
</ul>

<p><b>Further discussion from Redmond:</b></p>

<p>The basic problem is that we've defined our behavior,
including our error-reporting behavior, in terms of C90.  However,
C90's method of reporting overflow in scanf is not technically an
"input error".  The <tt>strto_*</tt> functions are more precise.</p>

<p>There was general consensus that <tt>failbit</tt> should be set
upon overflow.  We considered three options based on this:</p>
<ol>
<li>Set failbit upon conversion error (including overflow), and 
    don't store any value.</li>
<li>Set failbit upon conversion error, and also set <tt>errno</tt> to 
    indicated the precise nature of the error.</li>
<li>Set failbit upon conversion error.  If the error was due to
    overflow, store +-numeric_limits&lt;T&gt;::max() as an
    overflow indication.</li>
</ol>

<p>Straw poll: (1) 5; (2) 0; (3) 8.</p>


<p>Discussed at Lillehammer.  General outline of what we want the
  solution to look like: we want to say that overflow is an error, and
  provide a way to distinguish overflow from other kinds of errors.
  Choose candidate field the same way scanf does, but don't describe
  the rest of the process in terms of format.  If a finite input field
  is too large (positive or negative) to be represented as a finite
  value, then set failbit and assign the nearest representable value.
  Bill will provide wording.</p>

<p>
Discussed at Toronto:
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2327.pdf">N2327</a>
is in alignment with the direction we wanted to go with in Lillehammer.  Bill
to work on.
</p>



<p><b>Proposed resolution:</b></p>

<p>
Change 22.2.2.1.2 [facet.num.get.virtuals], end of p3:
</p>

<blockquote>
<p>
<b>Stage 3:</b> <del>The result of stage 2 processing can be one of</del>
<ins>The sequence of <tt>char</tt>s accumulated in stage 2 (the field) is
converted to a numeric value by the rules of one of the functions declared
in the header <tt>&lt;cstdlib&gt;</tt>:</ins>
</p>
<ul>
<li>
<del>A sequence of <tt>char</tt>s has been accumulated in stage 2 that is
converted (according to the rules of <tt>scanf</tt>) to a value of the
type of <i>val</i>. This value is stored in <i>val</i> and <tt>ios_base::goodbit</tt> is
stored in <i>err</i>.</del>
<ins>For a signed integer value, the function <tt>strtoll</tt>.</ins>
</li>
<li>
<del>The sequence of <tt>char</tt>s accumulated in stage 2 would have caused
<tt>scanf</tt> to report an input failure. <tt>ios_base::failbit</tt> is
assigned to <i>err</i>.</del>
<ins>For an unsigned integer value, the function <tt>strtoull</tt>.</ins>
</li>
<li>
<ins>For a floating-point value, the function <tt>strtold</tt>.</ins>
</li>
</ul>
<p>
<ins>The numeric value to be stored can be one of:</ins>
</p>
<ul>
<li><ins>zero, if the conversion function fails to convert the entire field.
<tt>ios_base::failbit</tt> is assigned to err.</ins></li>
<li><ins>the most positive representable value, if the field represents a value
too large positive to be represented in <i>val</i>. <tt>ios_base::failbit</tt> is assigned
to <i>err</i>.</ins></li>
<li><ins>the most negative representable value (zero for unsigned integer), if
the field represents a value too large negative to be represented in <i>val</i>.
<tt>ios_base::failbit</tt> is assigned to <i>err</i>.</ins></li>
<li><ins>the converted value, otherwise.</ins></li>
</ul>

<p><ins>
The resultant numeric value is stored in <i>val</i>.
</ins></p>
</blockquote>

<p>
Change 22.2.2.1.2 [facet.num.get.virtuals], p6-p7:
</p>

<blockquote>
<pre>iter_type do_get(iter_type <i>in</i>, iter_type <i>end</i>, ios_base&amp; <i>str</i>, 
                 ios_base::iostate&amp; <i>err</i>, bool&amp; <i>val</i>) const;
</pre>
<blockquote>
<p>
-6- <i>Effects:</i> If
<tt>(<i>str</i>.flags()&amp;ios_base::boolalpha)==0</tt> then input
proceeds as it would for a <tt>long</tt> except that if a value is being
stored into <i>val</i>, the value is determined according to the
following: If the value to be stored is 0 then <tt>false</tt> is stored.
If the value is 1 then <tt>true</tt> is stored. Otherwise
<del><tt><i>err</i>|=ios_base::failbit</tt> is performed and no value</del> <ins><tt>true</tt></ins> is
stored<del>.</del> <ins>and <tt>ios_base::failbit</tt> is assigned to <i>err</i>.</ins>
</p>
<p>
-7- Otherwise target sequences are determined "as if" by calling the
members <tt>falsename()</tt> and <tt>truename()</tt> of the facet
obtained by <tt>use_facet&lt;numpunct&lt;charT&gt;
&gt;(<i>str</i>.getloc())</tt>. Successive characters in the range
<tt>[<i>in</i>,<i>end</i>)</tt> (see 23.1.1) are obtained and matched
against corresponding positions in the target sequences only as
necessary to identify a unique match. The input iterator <i>in</i> is
compared to <i>end</i> only when necessary to obtain a character. If <del>and
only if</del> a target sequence is uniquely matched, <i>val</i> is set to the
corresponding value. <ins>Otherwise <tt>false</tt> is stored and <tt>ios_base::failbit</tt>
is assigned to <i>err</i>.</ins>
</p>
</blockquote>
</blockquote>





<hr>
<h3><a name="96"></a>96. Vector&lt;bool&gt; is not a container</h3>
<p><b>Section:</b> 23.2.5 [vector] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> AFNOR <b>Date:</b> 1998-10-07</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#vector">issues</a> in [vector].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p><tt>vector&lt;bool&gt;</tt> is not a container as its reference and
pointer types are not references and pointers. </p>

<p>Also it forces everyone to have a space optimization instead of a
speed one.</p>

<p><b>See also:</b> 99-0008 == N1185 Vector&lt;bool&gt; is
Nonconforming, Forces Optimization Choice.</p>

<p><i>[In Santa Cruz the LWG felt that this was Not A Defect.]</i></p>


<p><i>[In Dublin many present felt that failure to meet Container
requirements was a defect. There was disagreement as to whether
or not the optimization requirements constituted a defect.]</i></p>


<p><i>[The LWG looked at the following resolutions in some detail:
<br>
&nbsp;&nbsp;&nbsp;&nbsp; * Not A Defect.<br>
&nbsp;&nbsp;&nbsp;&nbsp; * Add a note explaining that vector&lt;bool&gt; does not meet
Container requirements.<br>
&nbsp;&nbsp;&nbsp;&nbsp; * Remove vector&lt;bool&gt;.<br>
&nbsp;&nbsp;&nbsp;&nbsp; * Add a new category of container requirements which
vector&lt;bool&gt; would meet.<br>
&nbsp;&nbsp;&nbsp;&nbsp; * Rename vector&lt;bool&gt;.<br>
<br>
No alternative had strong, wide-spread, support and every alternative
had at least one "over my dead body" response.<br>
<br>
There was also mention of a transition scheme something like (1) add
vector_bool and deprecate vector&lt;bool&gt; in the next standard. (2)
Remove vector&lt;bool&gt; in the following standard.]</i></p>


<p><i>[Modifying container requirements to permit returning proxies
(thus allowing container requirements conforming vector&lt;bool&gt;)
was also discussed.]</i></p>


<p><i>[It was also noted that there is a partial but ugly workaround in
that vector&lt;bool&gt; may be further specialized with a customer
allocator.]</i></p>


<p><i>[Kona: Herb Sutter presented his paper J16/99-0035==WG21/N1211,
vector&lt;bool&gt;: More Problems, Better Solutions. Much discussion
of a two step approach: a) deprecate, b) provide replacement under a
new name.  LWG straw vote on that: 1-favor, 11-could live with, 2-over
my dead body.  This resolution was mentioned in the LWG report to the
full committee, where several additional committee members indicated
over-my-dead-body positions.]</i></p>


<p>Discussed at Lillehammer.  General agreement that we should
  deprecate vector&lt;bool&gt; and introduce this functionality under
  a different name, e.g. bit_vector.  This might make it possible to
  remove the vector&lt;bool&gt; specialization in the standard that comes
  after C++0x. There was also a suggestion that
  in C++0x we could additional say that it's implementation defined
  whether vector&lt;bool&gt; refers to the specialization or to the
  primary template, but there wasn't general agreement that this was a
  good idea.</p>

<p>We need a paper for the new bit_vector class.</p>




<p><b>Proposed resolution:</b></p>
<p>
We now have:
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2050.pdf">N2050</a>
and
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2160.html">N2160</a>.
</p>

<p><i>[
Batavia: The LWG feels we need something closer to SGI's <tt>bitvector</tt> to ease migration
from <tt>vector&lt;bool&gt;</tt>.  Although some of the funcitonality from
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2050.pdf">N2050</a>
could well be used in such a template.  The concern is easing the API migration for those
users who want to continue using a bit-packed container.  Alan and Beman to work.
]</i></p>






<hr>
<h3><a name="255"></a>255. Why do <tt>basic_streambuf&lt;&gt;::pbump()</tt> and <tt>gbump()</tt> take an int?</h3>
<p><b>Section:</b> 27.5.2 [streambuf] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2000-08-12</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#streambuf">issues</a> in [streambuf].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The basic_streambuf members gbump() and pbump() are specified to take an
int argument. This requirement prevents the functions from effectively
manipulating buffers larger than std::numeric_limits&lt;int&gt;::max()
characters. It also makes the common use case for these functions
somewhat difficult as many compilers will issue a warning when an
argument of type larger than int (such as ptrdiff_t on LLP64
architectures) is passed to either of the function. Since it's often the
result of the subtraction of two pointers that is passed to the
functions, a cast is necessary to silence such warnings. Finally, the
usage of a native type in the functions signatures is inconsistent with
other member functions (such as sgetn() and sputn()) that manipulate the
underlying character buffer. Those functions take a streamsize argument.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change the signatures of these functions in the synopsis of template
class basic_streambuf (27.5.2) and in their descriptions (27.5.2.3.1, p4
and 27.5.2.3.2, p4) to take a streamsize argument.
</p>

<p>
Although this change has the potential of changing the ABI of the
library, the change will affect only platforms where int is different
than the definition of streamsize. However, since both functions are
typically inline (they are on all known implementations), even on such
platforms the change will not affect any user code unless it explicitly
relies on the existing type of the functions (e.g., by taking their
address). Such a possibility is IMO quite remote.
</p>

<p>
Alternate Suggestion from Howard Hinnant, c++std-lib-7780:
</p>

<p>
This is something of a nit, but I'm wondering if streamoff wouldn't be a 
better choice than streamsize.  The argument to pbump and gbump MUST be 
signed.  But the standard has this to say about streamsize 
(27.4.1/2/Footnote):
</p>

<blockquote><p>
     [Footnote: streamsize is used in most places where ISO C would use
     size_t.  Most of the uses of streamsize could use size_t, except for
     the strstreambuf constructors, which require negative values. It
     should probably be the signed type corresponding to size_t (which is
     what Posix.2 calls ssize_t). --- end footnote]
</p></blockquote>

<p>
This seems a little weak for the argument to pbump and gbump.  Should we 
ever really get rid of strstream, this footnote might go with it, along 
with the reason to make streamsize signed.
</p>


<p><b>Rationale:</b></p>
<p>The LWG believes this change is too big for now.  We may wish to
reconsider this for a future revision of the standard.  One
possibility is overloading pbump, rather than changing the
signature.</p>
<p><i>[
[2006-05-04: Reopened at the request of Chris (Krzysztof ?elechowski)]
]</i></p>





<hr>
<h3><a name="290"></a>290. Requirements to for_each and its function object</h3>
<p><b>Section:</b> 25.1.1 [alg.foreach] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Angelika Langer <b>Date:</b> 2001-01-03</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#alg.foreach">issues</a> in [alg.foreach].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>The specification of the for_each algorithm does not have a
"Requires" section, which means that there are no
restrictions imposed on the function object whatsoever. In essence it
means that I can provide any function object with arbitrary side
effects and I can still expect a predictable result. In particular I
can expect that the function object is applied exactly last - first
times, which is promised in the "Complexity" section.
</p>

<p>I don't see how any implementation can give such a guarantee
without imposing requirements on the function object.
</p>

<p>Just as an example: consider a function object that removes
elements from the input sequence.  In that case, what does the
complexity guarantee (applies f exactly last - first times) mean?
</p>

<p>One can argue that this is obviously a nonsensical application and
a theoretical case, which unfortunately it isn't.  I have seen
programmers shooting themselves in the foot this way, and they did not
understand that there are restrictions even if the description of the
algorithm does not say so.
</p>
<p><i>[Lillehammer: This is more general than for_each.  We don't want
  the function object in transform invalidiating iterators
  either. There should be a note somewhere in clause 17 (17, not 25)
  saying that user code operating on a range may not invalidate
  iterators unless otherwise specified.  Bill will provide wording.]</i></p>



<p><b>Proposed resolution:</b></p>






<hr>
<h3><a name="299"></a>299. Incorrect return types for iterator dereference</h3>
<p><b>Section:</b> 24.1.4 [bidirectional.iterators], 24.1.5 [random.access.iterators] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> John Potter <b>Date:</b> 2001-01-22</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#bidirectional.iterators">issues</a> in [bidirectional.iterators].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In section 24.1.4 [bidirectional.iterators],
Table 75 gives the return type of *r-- as convertible to T.  This is
not consistent with Table 74 which gives the return type of *r++ as
T&amp;.  *r++ = t is valid while *r-- = t is invalid.
</p>

<p>
In section 24.1.5 [random.access.iterators],
Table 76 gives the return type of a[n] as convertible to T.  This is
not consistent with the semantics of *(a + n) which returns T&amp; by
Table 74.  *(a + n) = t is valid while a[n] = t is invalid.
</p>

<p>
Discussion from the Copenhagen meeting: the first part is
uncontroversial.  The second part, operator[] for Random Access
Iterators, requires more thought.  There are reasonable arguments on
both sides.  Return by value from operator[] enables some potentially
useful iterators, e.g. a random access "iota iterator" (a.k.a
"counting iterator" or "int iterator").  There isn't any obvious way
to do this with return-by-reference, since the reference would be to a
temporary.  On the other hand, <tt>reverse_iterator</tt> takes an
arbitrary Random Access Iterator as template argument, and its
operator[] returns by reference.  If we decided that the return type
in Table 76 was correct, we would have to change
<tt>reverse_iterator</tt>.  This change would probably affect user
code.
</p>

<p>
History: the contradiction between <tt>reverse_iterator</tt> and the
Random Access Iterator requirements has been present from an early
stage.  In both the STL proposal adopted by the committee
(N0527==94-0140) and the STL technical report (HPL-95-11 (R.1), by
Stepanov and Lee), the Random Access Iterator requirements say that
operator[]'s return value is "convertible to T".  In N0527
reverse_iterator's operator[] returns by value, but in HPL-95-11
(R.1), and in the STL implementation that HP released to the public,
reverse_iterator's operator[] returns by reference.  In 1995, the
standard was amended to reflect the contents of HPL-95-11 (R.1).  The
original intent for operator[] is unclear.
</p>

<p>
In the long term it may be desirable to add more fine-grained 
iterator requirements, so that access method and traversal strategy
can be decoupled.  (See "Improved Iterator Categories and
Requirements", N1297 = 01-0011, by Jeremy Siek.)  Any decisions
about issue 299 should keep this possibility in mind.
</p>

<p>Further discussion: I propose a compromise between John Potter's
resolution, which requires <tt>T&amp;</tt> as the return type of
<tt>a[n]</tt>, and the current wording, which requires convertible to
<tt>T</tt>. The compromise is to keep the convertible to <tt>T</tt>
for the return type of the expression <tt>a[n]</tt>, but to also add
<tt>a[n] = t</tt> as a valid expression. This compromise "saves" the
common case uses of random access iterators, while at the same time
allowing iterators such as counting iterator and caching file
iterators to remain random access iterators (iterators where the
lifetime of the object returned by <tt>operator*()</tt> is tied to the
lifetime of the iterator).
</p>

<p>
Note that the compromise resolution necessitates a change to
<tt>reverse_iterator</tt>. It would need to use a proxy to support
<tt>a[n] = t</tt>.
</p>

<p>
Note also there is one kind of mutable random access iterator that
will no longer meet the new requirements. Currently, iterators that
return an r-value from <tt>operator[]</tt> meet the requirements for a
mutable random access iterartor, even though the expression <tt>a[n] =
t</tt> will only modify a temporary that goes away. With this proposed
resolution, <tt>a[n] = t</tt> will be required to have the same
operational semantics as <tt>*(a + n) = t</tt>.
</p>



<p><b>Proposed resolution:</b></p>

<p>
In section 24.1.4 [lib.bidirectdional.iterators], change the return
type in table 75 from "convertible to <tt>T</tt>" to
<tt>T&amp;</tt>.
</p>

<p>
In section 24.1.5 [lib.random.access.iterators], change the
operational semantics for <tt>a[n]</tt> to " the r-value of
<tt>a[n]</tt> is equivalent to the r-value of <tt>*(a +
n)</tt>". Add a new row in the table for the expression <tt>a[n] = t</tt>
with a return type of convertible to <tt>T</tt> and operational semantics of
<tt>*(a + n) = t</tt>.
</p>

<p><i>[Lillehammer: Real problem, but should be addressed as part of
  iterator redesign]</i></p>








<hr>
<h3><a name="309"></a>309. Does sentry catch exceptions?</h3>
<p><b>Section:</b> 27.6 [iostream.format] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2001-03-19</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#iostream.format">active issues</a> in [iostream.format].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#iostream.format">issues</a> in [iostream.format].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The descriptions of the constructors of basic_istream&lt;&gt;::sentry
(27.6.1.1.3 [istream::sentry]) and basic_ostream&lt;&gt;::sentry
(27.6.2.4 [ostream::sentry]) do not explain what the functions do in
case an exception is thrown while they execute. Some current
implementations allow all exceptions to propagate, others catch them
and set ios_base::badbit instead, still others catch some but let
others propagate.
</p>

<p>
The text also mentions that the functions may call setstate(failbit)
(without actually saying on what object, but presumably the stream
argument is meant).  That may have been fine for
basic_istream&lt;&gt;::sentry prior to issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#195">195</a>, since
the function performs an input operation which may fail. However,
issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#195">195</a> amends 27.6.1.1.3 [istream::sentry], p2 to
clarify that the function should actually call setstate(failbit |
eofbit), so the sentence in p3 is redundant or even somewhat
contradictory.
</p>

<p>
The same sentence that appears in 27.6.2.4 [ostream::sentry], p3
doesn't seem to be very meaningful for basic_istream&lt;&gt;::sentry
which performs no input. It is actually rather misleading since it
would appear to guide library implementers to calling
setstate(failbit) when os.tie()-&gt;flush(), the only called function,
throws an exception (typically, it's badbit that's set in response to
such an event).
</p>

<p><b>Additional comments from Martin, who isn't comfortable with the
    current proposed resolution</b> (see c++std-lib-11530)</p>

<p>
The istream::sentry ctor says nothing about how the function
deals with exemptions (27.6.1.1.2, p1 says that the class is
responsible for doing "exception safe"(*) prefix and suffix
operations but it doesn't explain what level of exception
safety the class promises to provide). The mockup example
of a "typical implementation of the sentry ctor" given in
27.6.1.1.2, p6, removed in ISO/IEC 14882:2003, doesn't show
exception handling, either. Since the ctor is not classified
as a formatted or unformatted input function, the text in
27.6.1.1, p1 through p4 does not apply. All this would seem
to suggest that the sentry ctor should not catch or in any
way handle exceptions thrown from any functions it may call.
Thus, the typical implementation of an istream extractor may
look something like [1].
</p>

<p>
The problem with [1] is that while it correctly sets ios::badbit
if an exception is thrown from one of the functions called from
the sentry ctor, if the sentry ctor reaches EOF while extracting
whitespace from a stream that has eofbit or failbit set in
exceptions(), it will cause an ios::failure to be thrown, which
will in turn cause the extractor to set ios::badbit.
</p>

<p>
The only straightforward way to prevent this behavior is to
move the definition of the sentry object in the extractor
above the try block (as suggested by the example in 22.2.8,
p9 and also indirectly supported by 27.6.1.3, p1). See [2].
But such an implementation will allow exceptions thrown from
functions called from the ctor to freely propagate to the
caller regardless of the setting of ios::badbit in the stream
object's exceptions().
</p>

<p>
So since neither [1] nor [2] behaves as expected, the only
possible solution is to have the sentry ctor catch exceptions
thrown from called functions, set badbit, and propagate those
exceptions if badbit is also set in exceptions(). (Another
solution exists that deals with both kinds of sentries, but
the code is non-obvious and cumbersome -- see [3].)
</p>

<p>
Please note that, as the issue points out, current libraries
do not behave consistently, suggesting  that implementors are
not quite clear on the exception handling in istream::sentry,
despite the fact that some LWG members might feel otherwise.
(As documented by the parenthetical comment here:
http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1480.html#309)
</p>

<p>
Also please note that those LWG members who in Copenhagen
felt that "a sentry's constructor should not catch exceptions,
because sentries should only be used within (un)formatted input
functions and that exception handling is the responsibility of
those functions, not of the sentries," as noted here
http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2001/n1310.html#309
would in effect be either arguing for the behavior described
in [1] or for extractors implemented along the lines of [3].
</p>

<p>
The original proposed resolution (Revision 25 of the issues
list) clarifies the role of the sentry ctor WRT exception
handling by making it clear that extractors (both library
or user-defined) should be implemented along the lines of
[2] (as opposed to [1]) and that no exception thrown from
the callees should propagate out of either function unless
badbit is also set in exceptions().
</p>


<p>[1] Extractor that catches exceptions thrown from sentry:</p>

<blockquote>
<pre>struct S { long i; };

istream&amp; operator&gt;&gt; (istream &amp;strm, S &amp;s)
{
    ios::iostate err = ios::goodbit;
    try {
        const istream::sentry guard (strm, false);
        if (guard) {
            use_facet&lt;num_get&lt;char&gt; &gt;(strm.getloc ())
                .get (istreambuf_iterator&lt;char&gt;(strm),
                      istreambuf_iterator&lt;char&gt;(),
                      strm, err, s.i);
        }
    }
    catch (...) {
        bool rethrow;
        try {
            strm.setstate (ios::badbit);
            rethrow = false;
        }
        catch (...) {
            rethrow = true;
        }
        if (rethrow)
            throw;
    }
    if (err)
        strm.setstate (err);
    return strm;
}
</pre>
</blockquote>

<p>[2] Extractor that propagates exceptions thrown from sentry:</p>

<blockquote>
<pre>istream&amp; operator&gt;&gt; (istream &amp;strm, S &amp;s)
{
    istream::sentry guard (strm, false);
    if (guard) {
        ios::iostate err = ios::goodbit;
        try {
            use_facet&lt;num_get&lt;char&gt; &gt;(strm.getloc ())
                .get (istreambuf_iterator&lt;char&gt;(strm),
                      istreambuf_iterator&lt;char&gt;(),
                      strm, err, s.i);
        }
        catch (...) {
            bool rethrow;
            try {
                strm.setstate (ios::badbit);
                rethrow = false;
            }
            catch (...) {
                rethrow = true;
            }
            if (rethrow)
                throw;
        }
        if (err)
            strm.setstate (err);
    }
    return strm;
}
</pre>
</blockquote>

<p>
[3] Extractor that catches exceptions thrown from sentry
but doesn't set badbit if the exception was thrown as a
result of a call to strm.clear().
</p>

<blockquote>
<pre>istream&amp; operator&gt;&gt; (istream &amp;strm, S &amp;s)
{
    const ios::iostate state = strm.rdstate ();
    const ios::iostate except = strm.exceptions ();
    ios::iostate err = std::ios::goodbit;
    bool thrown = true;
    try {
        const istream::sentry guard (strm, false);
        thrown = false;
        if (guard) {
            use_facet&lt;num_get&lt;char&gt; &gt;(strm.getloc ())
                .get (istreambuf_iterator&lt;char&gt;(strm),
                      istreambuf_iterator&lt;char&gt;(),
                      strm, err, s.i);
        }
    }
    catch (...) {
        if (thrown &amp;&amp; state &amp; except)
            throw;
        try {
            strm.setstate (ios::badbit);
            thrown = false;
        }
        catch (...) {
            thrown = true;
        }
        if (thrown)
            throw;
    }
    if (err)
        strm.setstate (err);

    return strm;
}
</pre>
</blockquote>

<p>
[Pre-Berlin] Reopened at the request of Paolo Carlini and Steve Clamage.
</p>

<p>
[Pre-Portland] A relevant newsgroup post:
</p>

<p>
The current proposed resolution of issue #309
(http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#309)  is
unacceptable.   I write commerical software and coding around this
makes my code ugly, non-intuitive, and requires comments referring
people to this very issue.   Following is the full explanation of my
experience.
</p>
<p>
In the course of writing software for commercial use, I constructed
std::ifstream's based on user-supplied pathnames on typical POSIX
systems.
</p>
<p>
It was expected that some files that opened successfully might not read
successfully -- such as a pathname which actually refered to a
directory.   Intuitively, I expected the streambuffer underflow() code
to throw an exception in this situation, and recent implementations of
libstdc++'s basic_filebuf do just that (as well as many of my own
custom streambufs).
</p>
<p>
I also intuitively expected that the istream code would convert these
exceptions to the "badbit' set on the stream object, because I had not
requested exceptions.    I refer to 27.6.1.1. P4.
</p>
<p>
However, this was not the case on at least two implementations -- if
the first thing I did with an istream was call operator&gt;&gt;( T&amp; ) for T
among the basic arithmetic types and std::string.   Looking further I
found that the sentry's constructor was invoking the exception when it
pre-scanned for whitespace, and the extractor function (operator&gt;&gt;())
was not catching exceptions in this situation.
</p>
<p>
So, I was in a situation where setting 'noskipws' would change the
istream's behavior even though no characters (whitespace or not) could
ever be successfully read.
</p>
<p>
Also, calling .peek() on the istream before calling the extractor()
changed the behavior (.peek() had the effect of setting the badbit
ahead of time).
</p>
<p>
I found this all to be so inconsistent and inconvenient for me and my
code design, that I filed a bugzilla entry for libstdc++.   I was then
told that the bug cannot be fixed until issue #309 is resolved by the
committee.
</p>



<p><b>Proposed resolution:</b></p>


<p><b>Rationale:</b></p>
<p>The LWG agrees there is minor variation between implementations,
  but believes that it doesn't matter. This is a rarely used corner
  case. There is no evidence that this has any commercial importance
  or that it causes actual portability problems for customers trying
  to write code that runs on multiple implementations.</p>





<hr>
<h3><a name="342"></a>342. seek and eofbit</h3>
<p><b>Section:</b> 27.6.1.3 [istream.unformatted] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2001-10-09</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#istream.unformatted">issues</a> in [istream.unformatted].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>I think we have a defect.</p>

<p>According to lwg issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#60">60</a> which is now a dr, the
description of seekg in 27.6.1.3 [istream.unformatted] paragraph 38 now looks
like:</p>

<blockquote><p>
Behaves as an unformatted input function (as described in 27.6.1.3, 
paragraph 1), except that it does not count the number of characters 
extracted and does not affect the value returned by subsequent calls to 
gcount(). After constructing a sentry object, if fail() != true, 
executes rdbuf()-&gt;pubseekpos( pos).
</p></blockquote>

<p>And according to lwg issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#243">243</a> which is also now a dr,
27.6.1.3, paragraph 1 looks like:</p>

<blockquote><p>
Each unformatted input function begins execution by constructing an 
object of class sentry with the default argument noskipws (second) 
argument true. If the sentry object returns true, when converted to a 
value of type bool, the function endeavors to obtain the requested 
input.  Otherwise, if the sentry constructor exits by throwing an 
exception or if the sentry object returns false, when converted to a 
value of type bool, the function returns without attempting to obtain 
any input. In either case the number of extracted characters is set to 
0; unformatted input functions taking a character array of non-zero 
size as an argument shall also store a null character (using charT()) 
in the first location of the array. If an exception is thrown during 
input then ios::badbit is turned on in *this'ss error state. If 
(exception()&amp;badbit)!= 0 then the exception is rethrown. It also counts 
the number of characters extracted. If no exception has been thrown it 
ends by storing the count in a member object and returning the value 
specified. In any event the sentry object is destroyed before leaving 
the unformatted input function.
</p></blockquote>

<p>And finally 27.6.1.1.2/5 says this about sentry:</p>

<blockquote><p>
If, after any preparation is completed, is.good() is true, ok_ != false 
otherwise, ok_ == false.
</p></blockquote>

<p>
So although the seekg paragraph says that the operation proceeds if 
!fail(), the behavior of unformatted functions says the operation 
proceeds only if good().  The two statements are contradictory when only 
eofbit is set.  I don't think the current text is clear which condition 
should be respected.
</p>

<p><b>Further discussion from Redmond:</b></p>

<p>PJP: It doesn't seem quite right to say that <tt>seekg</tt> is
"unformatted". That makes specific claims about sentry that
aren't quite appropriate for seeking, which has less fragile failure
modes than actual input.  If we do really mean that it's unformatted
input, it should behave the same way as other unformatted input.  On
the other hand, "principle of least surprise" is that seeking from EOF
ought to be OK.</p>

<p>
Pre-Berlin:  Paolo points out several problems with the proposed resolution in
Ready state:
</p>

<ul>
<li>It should apply to both overloads of seekg.</li>
<li>tellg has similar issues, except that it should not call clear().</li>
<li>The point about clear() seems to apply to seekp().</li>
<li>Depending on the outcome of <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#419">419</a>
if the sentry
sets <tt>failbit</tt> when it finds <tt>eofbit</tt> already set, then
you can never seek away from the end of stream.</li>
</ul>



<p><b>Proposed resolution:</b></p>

<p>Change 27.6.1.3 [istream.unformatted] to:</p>
<blockquote><p>
Behaves as an unformatted input function (as described in 27.6.1.3,
paragraph 1), except that it does not count the number of characters
extracted, does not affect the value returned by subsequent calls to
gcount(), and does not examine the value returned by the sentry
object. After constructing a sentry object, if <tt>fail() !=
true</tt>, executes <tt>rdbuf()-&gt;pubseekpos(pos)</tt>.  In
case of success, the function calls clear().
In case of failure, the function calls <tt>setstate(failbit)</tt>
(which may throw <tt>ios_base::failure</tt>).
</p></blockquote>

<p><i>[Lillehammer: Matt provided wording.]</i></p>




<p><b>Rationale:</b></p>
<p>In C, fseek does clear EOF.  This is probably what most users would
  expect.  We agree that having eofbit set should not deter a seek,
  and that a successful seek should clear eofbit. Note
  that <tt>fail()</tt> is true only if <tt>failbit</tt>
  or <tt>badbit</tt> is set, so using <tt>!fail()</tt>, rather
  than <tt>good()</tt>, satisfies this goal.</p>





<hr>
<h3><a name="343"></a>343. Unspecified library header dependencies</h3>
<p><b>Section:</b> 21 [strings], 23 [containers], 27 [input.output] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2001-10-09</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#strings">issues</a> in [strings].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The synopses of the C++ library headers clearly show which names are
required to be defined in each header. Since in order to implement the
classes and templates defined in these headers declarations of other
templates (but not necessarily their definitions) are typically
necessary the standard in 17.4.4, p1 permits library implementers to
include any headers needed to implement the definitions in each header.
</p>

<p>
For instance, although it is not explicitly specified in the synopsis of
&lt;string&gt;, at the point of definition of the std::basic_string template
the declaration of the std::allocator template must be in scope. All
current implementations simply include &lt;memory&gt; from within &lt;string&gt;,
either directly or indirectly, to bring the declaration of
std::allocator into scope.
</p>

<p>
Additionally, however, some implementation also include &lt;istream&gt; and
&lt;ostream&gt; at the top of &lt;string&gt; to bring the declarations of
std::basic_istream and std::basic_ostream into scope (which are needed
in order to implement the string inserter and extractor operators
(21.3.7.9 [lib.string.io])). Other implementations only include
&lt;iosfwd&gt;, since strictly speaking, only the declarations and not the
full definitions are necessary.
</p>

<p>
Obviously, it is possible to implement &lt;string&gt; without actually
providing the full definitions of all the templates std::basic_string
uses (std::allocator, std::basic_istream, and std::basic_ostream).
Furthermore, not only is it possible, doing so is likely to have a
positive effect on compile-time efficiency.
</p>

<p>
But while it may seem perfectly reasonable to expect a program that uses
the std::basic_string insertion and extraction operators to also
explicitly include &lt;istream&gt; or &lt;ostream&gt;, respectively, it doesn't seem
reasonable to also expect it to explicitly include &lt;memory&gt;. Since
what's reasonable and what isn't is highly subjective one would expect
the standard to specify what can and what cannot be assumed.
Unfortunately, that isn't the case.
</p>

<p>The examples below demonstrate the issue.</p>

<p>Example 1:</p>

<p>It is not clear whether the following program is complete:</p>

<pre>#include &lt;string&gt;

extern std::basic_ostream&lt;char&gt; &amp;strm;

int main () {
    strm &lt;&lt; std::string ("Hello, World!\n");
}
</pre>    

<p>or whether one must explicitly include &lt;memory&gt; or
&lt;ostream&gt; (or both) in addition to &lt;string&gt; in order for
the program to compile.</p>


<p>Example 2:</p>

<p>Similarly, it is unclear whether the following program is complete:</p>

<pre>#include &lt;istream&gt;

extern std::basic_iostream&lt;char&gt; &amp;strm;

int main () {
    strm &lt;&lt; "Hello, World!\n";
}
</pre>

<p>
or whether one needs to explicitly include &lt;ostream&gt;, and
perhaps even other headers containing the definitions of other
required templates:</p>

<pre>#include &lt;ios&gt;
#include &lt;istream&gt;
#include &lt;ostream&gt;
#include &lt;streambuf&gt;

extern std::basic_iostream&lt;char&gt; &amp;strm;

int main () {
    strm &lt;&lt; "Hello, World!\n";
}
</pre>

<p>Example 3:</p>

<p>Likewise, it seems unclear whether the program below is complete:</p>
<pre>#include &lt;iterator&gt;

bool foo (std::istream_iterator&lt;int&gt; a, std::istream_iterator&lt;int&gt; b)
{
    return a == b;
}

int main () { }
</pre>

<p>or whether one should be required to include &lt;istream&gt;.</p>

<p>There are many more examples that demonstrate this lack of a
requirement.  I believe that in a good number of cases it would be
unreasonable to require that a program explicitly include all the
headers necessary for a particular template to be specialized, but I
think that there are cases such as some of those above where it would
be desirable to allow implementations to include only as much as
necessary and not more.</p>


<p><b>Proposed resolution:</b></p>
<p>
For every C++ library header, supply a minimum set of other C++ library
headers that are required to be included by that header. The proposed
list is below (C++ headers for C Library Facilities, table 12 in
17.4.1.2, p3, are omitted):
</p>

<pre>+------------+--------------------+
| C++ header |required to include |
+============+====================+
|&lt;algorithm&gt; |                    |
+------------+--------------------+
|&lt;bitset&gt;    |                    |
+------------+--------------------+
|&lt;complex&gt;   |                    |
+------------+--------------------+
|&lt;deque&gt;     |&lt;memory&gt;            |
+------------+--------------------+
|&lt;exception&gt; |                    |
+------------+--------------------+
|&lt;fstream&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;functional&gt;|                    |
+------------+--------------------+
|&lt;iomanip&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;ios&gt;       |&lt;streambuf&gt;         |
+------------+--------------------+
|&lt;iosfwd&gt;    |                    |
+------------+--------------------+
|&lt;iostream&gt;  |&lt;istream&gt;, &lt;ostream&gt;|
+------------+--------------------+
|&lt;istream&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;iterator&gt;  |                    |
+------------+--------------------+
|&lt;limits&gt;    |                    |
+------------+--------------------+
|&lt;list&gt;      |&lt;memory&gt;            |
+------------+--------------------+
|&lt;locale&gt;    |                    |
+------------+--------------------+
|&lt;map&gt;       |&lt;memory&gt;            |
+------------+--------------------+
|&lt;memory&gt;    |                    |
+------------+--------------------+
|&lt;new&gt;       |&lt;exception&gt;         |
+------------+--------------------+
|&lt;numeric&gt;   |                    |
+------------+--------------------+
|&lt;ostream&gt;   |&lt;ios&gt;               |
+------------+--------------------+
|&lt;queue&gt;     |&lt;deque&gt;             |
+------------+--------------------+
|&lt;set&gt;       |&lt;memory&gt;            |
+------------+--------------------+
|&lt;sstream&gt;   |&lt;ios&gt;, &lt;string&gt;     |
+------------+--------------------+
|&lt;stack&gt;     |&lt;deque&gt;             |
+------------+--------------------+
|&lt;stdexcept&gt; |                    |
+------------+--------------------+
|&lt;streambuf&gt; |&lt;ios&gt;               |
+------------+--------------------+
|&lt;string&gt;    |&lt;memory&gt;            |
+------------+--------------------+
|&lt;strstream&gt; |                    |
+------------+--------------------+
|&lt;typeinfo&gt;  |&lt;exception&gt;         |
+------------+--------------------+
|&lt;utility&gt;   |                    |
+------------+--------------------+
|&lt;valarray&gt;  |                    |
+------------+--------------------+
|&lt;vector&gt;    |&lt;memory&gt;            |
+------------+--------------------+
</pre>


<p><b>Rationale:</b></p>
<p>The portability problem is real.  A program that works correctly on
one implementation might fail on another, because of different header
dependencies.  This problem was understood before the standard was
completed, and it was a conscious design choice.</p>
<p>One possible way to deal with this, as a library extension, would
be an &lt;all&gt; header.</p>

<p>
Hinnant:  It's time we dealt with this issue for C++0X.  Reopened.
</p>







<hr>
<h3><a name="382"></a>382. codecvt do_in/out result</h3>
<p><b>Section:</b> 22.2.1.4 [locale.codecvt] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2002-08-30</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.codecvt">issues</a> in [locale.codecvt].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
It seems that the descriptions of codecvt do_in() and do_out() leave
sufficient room for interpretation so that two implementations of
codecvt may not work correctly with the same filebuf. Specifically,
the following seems less than adequately specified:
</p>

<ol>
<li>
  the conditions under which the functions terminate
</li>
<li>
  precisely when the functions return ok
</li>
<li>
  precisely when the functions return partial
</li>
<li>
  the full set of conditions when the functions return error
</li>
</ol>

<ol>
<li>
   22.2.1.4.2 [locale.codecvt.virtuals], p2 says this about the effects of the
   function: ...Stops if it encounters a character it cannot
   convert...  This assumes that there *is* a character to
   convert. What happens when there is a sequence that doesn't form a
   valid source character, such as an unassigned or invalid UNICODE
   character, or a sequence that cannot possibly form a character
   (e.g., the sequence "\xc0\xff" in UTF-8)?
</li>
<li>
   Table 53 says that the function returns codecvt_base::ok
   to indicate that the function(s) "completed the conversion."
   Suppose that the source sequence is "\xc0\x80" in UTF-8,
   with from pointing to '\xc0' and (from_end==from + 1).
   It is not clear whether the return value should be ok
   or partial (see below).
</li>
<li>
   Table 53 says that the function returns codecvt_base::partial
   if "not all source characters converted." With the from pointers
   set up the same way as above, it is not clear whether the return
   value should be partial or ok (see above).
</li>
<li>
   Table 53, in the row describing the meaning of error mistakenly
   refers to a "from_type" character, without the symbol from_type
   having been defined. Most likely, the word "source" character
   is intended, although that is not sufficient. The functions
   may also fail when they encounter an invalid source sequence
   that cannot possibly form a valid source character (e.g., as
   explained in bullet 1 above).
</li>
</ol>
<p>
Finally, the conditions described at the end of 22.2.1.4.2 [locale.codecvt.virtuals], p4 don't seem to be possible:
</p>
<blockquote><p>
    "A return value of partial, if (from_next == from_end),
    indicates that either the destination sequence has not
    absorbed all the available destination elements, or that
    additional source elements are needed before another
    destination element can be produced."
</p></blockquote>
<p>
If the value is partial, it's not clear to me that (from_next
==from_end) could ever hold if there isn't enough room
in the destination buffer. In order for (from_next==from_end) to
hold, all characters in that range must have been successfully
converted (according to 22.2.1.4.2 [locale.codecvt.virtuals], p2) and since there are no
further source characters to convert, no more room in the
destination buffer can be needed.
</p>
<p>
It's also not clear to me that (from_next==from_end) could ever
hold if additional source elements are needed to produce another
destination character (not element as incorrectly stated in the
text). partial is returned if "not all source characters have
been converted" according to Table 53, which also implies that
(from_next==from) does NOT hold.
</p>
<p>
Could it be that the intended qualifying condition was actually
(from_next != from_end), i.e., that the sentence was supposed
to read
</p>
<blockquote><p>
    "A return value of partial, if (from_next != from_end),..."
</p></blockquote>
<p>
which would make perfect sense, since, as far as I understand it,
partial can only occur if (from_next != from_end)?
</p>
<p><i>[Lillehammer: Defer for the moment, but this really needs to be
  fixed. Right now, the description of codecvt is too vague for it to
  be a useful contract between providers and clients of codecvt
  facets.  (Note that both vendors and users can be both providers and
  clients of codecvt facets.) The major philosophical issue is whether
  the standard should only describe mappings that take a single wide
  character to multiple narrow characters (and vice versa), or whether
  it should describe fully general N-to-M conversions. When the
  original standard was written only the former was contemplated, but
  today, in light of the popularity of utf8 and utf16, that doesn't
  seem sufficient for C++0x. Bill supports general N-to-M conversions;
  we need to make sure Martin and Howard agree.]</i></p>



<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="387"></a>387. std::complex over-encapsulated</h3>
<p><b>Section:</b> 26.3 [complex.numbers] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Gabriel Dos Reis <b>Date:</b> 2002-11-08</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#complex.numbers">issues</a> in [complex.numbers].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The absence of explicit description of std::complex&lt;T&gt; layout
makes it imposible to reuse existing software developed in traditional
languages like Fortran or C with unambigous and commonly accepted
layout assumptions.  There ought to be a way for practitioners to
predict with confidence the layout of std::complex&lt;T&gt; whenever T
is a numerical datatype.  The absence of ways to access individual
parts of a std::complex&lt;T&gt; object as lvalues unduly promotes
severe pessimizations. For example, the only way to change,
independently, the real and imaginary parts is to write something like
</p>

<pre>complex&lt;T&gt; z;
// ...
// set the real part to r
z = complex&lt;T&gt;(r, z.imag());
// ...
// set the imaginary part to i
z = complex&lt;T&gt;(z.real(), i);
</pre>

<p>
At this point, it seems appropriate to recall that a complex number
is, in effect, just a pair of numbers with no particular invariant to
maintain.  Existing practice in numerical computations has it that a
complex number datatype is usually represented by Cartesian
coordinates. Therefore the over-encapsulation put in the specification
of std::complex&lt;&gt; is not justified.
</p>



<p><b>Proposed resolution:</b></p>
<p>Add the following requirements to 26.3 [complex.numbers] as 26.3/4:</p>
<blockquote>
<p>If z is an lvalue expression of type cv std::complex&lt;T&gt; then</p>

<ul>
<li>the expression reinterpret_cast&lt;cv T(&amp;)[2]&gt;(z)
is well-formed; and</li>
<li>reinterpret_cast&lt;cvT(&amp;)[2]&gt;(z)[0]designates the
real part of z; and</li>
<li>reinterpret_cast&lt;cvT(&amp;)[2]&gt;(z)[1]designates the
imaginary part of z.</li>
</ul>

<p>
Moreover, if a is an expression of pointer type cv complex&lt;T&gt;*
and the expression a[i] is well-defined for an integer expression
i then:
</p>

<ul>
<li>reinterpret_cast&lt;cvT*&gt;(a)[2+i] designates the real
part of a[i]; and</li>
<li>reinterpret_cast&lt;cv T*&gt;(a)[2+i+1] designates the
imaginary part of a[i].</li>
</ul>
</blockquote>

<p>In the header synopsis in 26.3.1 [complex.synopsis], replace</p>
<pre>  template&lt;class T&gt; T real(const complex&lt;T&gt;&amp;);
  template&lt;class T&gt; T imag(const complex&lt;T&gt;&amp;);
</pre>

<p>with</p>

<pre>  template&lt;class T&gt; const T&amp; real(const complex&lt;T&gt;&amp;);
  template&lt;class T&gt;       T&amp; real(      complex&lt;T&gt;&amp;);
  template&lt;class T&gt; const T&amp; imag(const complex&lt;T&gt;&amp;);
  template&lt;class T&gt;       T&amp; imag(      complex&lt;T&gt;&amp;);
</pre>

<p>In 26.3.7 [complex.value.ops] paragraph 1, change</p>
<pre>  template&lt;class T&gt; T real(const complex&lt;T&gt;&amp;);
</pre>
<p>to</p>
<pre>  template&lt;class T&gt; const T&amp; real(const complex&lt;T&gt;&amp;);
  template&lt;class T&gt;       T&amp; real(      complex&lt;T&gt;&amp;);
</pre>
<p>and change the <b>Returns</b> clause to "<b>Returns:</b> The real
part of <i>x</i>.</p>

<p>In 26.3.7 [complex.value.ops] paragraph 2, change</p>
<pre>  template&lt;class T&gt; T imag(const complex&lt;T&gt;&amp;);
</pre>
<p>to</p>
<pre>  template&lt;class T&gt; const T&amp; imag(const complex&lt;T&gt;&amp;);
  template&lt;class T&gt;       T&amp; imag(      complex&lt;T&gt;&amp;);
</pre>
<p>and change the <b>Returns</b> clause to "<b>Returns:</b> The imaginary
part of <i>x</i>.</p>

<p><i>[Kona: The layout guarantee is absolutely necessary for C
  compatibility.  However, there was disagreement about the other part
  of this proposal: retrieving elements of the complex number as
  lvalues.  An alternative: continue to have real() and imag() return
  rvalues, but add set_real() and set_imag().  Straw poll: return
  lvalues - 2, add setter functions - 5.  Related issue: do we want
  reinterpret_cast as the interface for converting a complex to an
  array of two reals, or do we want to provide a more explicit way of
  doing it?  Howard will try to resolve this issue for the next
  meeting.]</i></p>


<p><i>[pre-Sydney: Howard summarized the options in n1589.]</i></p>




<p><b>Rationale:</b></p>
<p>The LWG believes that C99 compatibility would be enough
justification for this change even without other considerations.  All
existing implementations already have the layout proposed here.</p>





<hr>
<h3><a name="394"></a>394. behavior of formatted output on failure</h3>
<p><b>Section:</b> 27.6.2.6.1 [ostream.formatted.reqmts] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2002-12-27</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
There is a contradiction in Formatted output about what bit is
supposed to be set if the formatting fails. On sentence says it's
badbit and another that it's failbit.
</p>
<p>
27.6.2.5.1, p1 says in the Common Requirements on Formatted output
functions:
</p>
<pre>     ... If the generation fails, then the formatted output function
     does setstate(ios::failbit), which might throw an exception.
</pre>
<p>
27.6.2.5.2, p1 goes on to say this about Arithmetic Inserters:
</p>
<p>
     ... The formatting conversion occurs as if it performed the
     following code fragment:
</p>
<pre>     bool failed =
         use_facet&lt;num_put&lt;charT,ostreambuf_iterator&lt;charT,traits&gt;
         &gt; &gt;
         (getloc()).put(*this, *this, fill(), val). failed();

     ... If failed is true then does setstate(badbit) ...
</pre>
<p>
The original intent of the text, according to Jerry Schwarz (see
c++std-lib-10500), is captured in the following paragraph:
</p>
<p>
In general "badbit" should mean that the stream is unusable because
of some underlying failure, such as disk full or socket closure;
"failbit" should mean that the requested formatting wasn't possible
because of some inconsistency such as negative widths.  So typically
if you clear badbit and try to output something else you'll fail
again, but if you clear failbit and try to output something else
you'll succeed.
</p>
<p>
In the case of the arithmetic inserters, since num_put cannot
report failure by any means other than exceptions (in response
to which the stream must set badbit, which prevents the kind of
recoverable error reporting mentioned above), the only other
detectable failure is if the iterator returned from num_put
returns true from failed().
</p>
<p>
Since that can only happen (at least with the required iostream
specializations) under such conditions as the underlying failure
referred to above (e.g., disk full), setting badbit would seem
to be the appropriate response (indeed, it is required in
27.6.2.5.2, p1). It follows that failbit can never be directly
set by the arithmetic (it can only be set by the sentry object
under some unspecified conditions).
</p>
<p>
The situation is different for other formatted output functions
which can fail as a result of the streambuf functions failing
(they may do so by means other than exceptions), and which are
then required to set failbit.
</p>
<p>
The contradiction, then, is that ostream::operator&lt;&lt;(int) will
set badbit if the disk is full, while operator&lt;&lt;(ostream&amp;,
char) will set failbit under the same conditions. To make the behavior
consistent, the Common requirements sections for the Formatted output
functions should be changed as proposed below.
</p>
<p><i>[Kona: There's agreement that this is a real issue.  What we
  decided at Kona: 1. An error from the buffer (which can be detected
  either directly from streambuf's member functions or by examining a
  streambuf_iterator) should always result in badbit getting set.
  2. There should never be a circumstance where failbit gets set.
  That represents a formatting error, and there are no circumstances
  under which the output facets are specified as signaling a
  formatting error. (Even more so for string output that for numeric
  because there's nothing to format.)  If we ever decide to make it
  possible for formatting errors to exist then the facets can signal
  the error directly, and that should go in clause 22, not clause 27.
  3. The phrase "if generation fails" is unclear and should be
  eliminated.  It's not clear whether it's intended to mean a buffer
  error (e.g. a full disk), a formatting error, or something else.
  Most people thought it was supposed to refer to buffer errors; if
  so, we should say so.  Martin will provide wording.]</i></p>




<p><b>Proposed resolution:</b></p>


<p><b>Rationale:</b></p>






<hr>
<h3><a name="396"></a>396. what are characters zero and one</h3>
<p><b>Section:</b> 23.3.5.1 [bitset.cons] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-01-05</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#bitset.cons">issues</a> in [bitset.cons].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
    <p>
23.3.5.1, p6 [lib.bitset.cons] talks about a generic character
having the value of 0 or 1 but there is no definition of what
that means for charT other than char and wchar_t. And even for
those two types, the values 0 and 1 are not actually what is
intended -- the values '0' and '1' are. This, along with the
converse problem in the description of to_string() in 23.3.5.2,
p33, looks like a defect remotely related to DR 303.
    </p>
    <p>
http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#303
    </p>
    <pre>23.3.5.1:
  -6-  An element of the constructed string has value zero if the
       corresponding character in str, beginning at position pos,
       is 0. Otherwise, the element has the value one.
    </pre>
    <pre>23.3.5.2:
  -33-  Effects: Constructs a string object of the appropriate
        type and initializes it to a string of length N characters.
        Each character is determined by the value of its
        corresponding bit position in *this. Character position N
        ?- 1 corresponds to bit position zero. Subsequent decreasing
        character positions correspond to increasing bit positions.
        Bit value zero becomes the character 0, bit value one becomes
        the character 1.
    </pre>
    <p>
Also note the typo in 23.3.5.1, p6: the object under construction
is a bitset, not a string.
    </p>
  

<p><b>Proposed resolution:</b></p>
<p>Change the constructor's function declaration immediately before 
23.3.5.1 [bitset.cons] p3 to:</p>
<pre>    template &lt;class charT, class traits, class Allocator&gt;
    explicit
    bitset(const basic_string&lt;charT, traits, Allocator&gt;&amp; str,
           typename basic_string&lt;charT, traits, Allocator&gt;::size_type pos = 0,
           typename basic_string&lt;charT, traits, Allocator&gt;::size_type n =
             basic_string&lt;charT, traits, Allocator&gt;::npos,
           charT zero = charT('0'), charT one = charT('1'))
</pre>
<p>Change the first two sentences of 23.3.5.1 [bitset.cons] p6 to: "An
element of the constructed string has value 0 if the corresponding
character in <i>str</i>, beginning at position <i>pos</i>,
is <i>zero</i>. Otherwise, the element has the value 1.</p>

<p>Change the text of the second sentence in 23.3.5.1, p5 to read:
    "The function then throws invalid_argument if any of the rlen
    characters in str beginning at position pos is other than <i>zero</i>
    or <i>one</i>. The function uses traits::eq() to compare the character
    values."
</p>

<p>Change the declaration of the <tt>to_string</tt> member function
  immediately before 23.3.5.2 [bitset.members] p33 to:</p>
<pre>    template &lt;class charT, class traits, class Allocator&gt;
    basic_string&lt;charT, traits, Allocator&gt; 
    to_string(charT zero = charT('0'), charT one = charT('1')) const;
</pre>
<p>Change the last sentence of 23.3.5.2 [bitset.members] p33 to: "Bit
  value 0 becomes the character <tt><i>zero</i></tt>, bit value 1 becomes the
  character <tt><i>one</i></tt>.</p>
<p>Change 23.3.5.3 [bitset.operators] p8 to:</p>
<p><b>Returns</b>:</p> 
<pre>  os &lt;&lt; x.template to_string&lt;charT,traits,allocator&lt;charT&gt; &gt;(
      use_facet&lt;ctype&lt;charT&gt; &gt;(<i>os</i>.getloc()).widen('0'),
      use_facet&lt;ctype&lt;charT&gt; &gt;(<i>os</i>.getloc()).widen('1'));
</pre>


<p><b>Rationale:</b></p>
<p>There is a real problem here: we need the character values of '0'
  and '1', and we have no way to get them since strings don't have
  imbued locales. In principle the "right" solution would be to
  provide an extra object, either a ctype facet or a full locale,
  which would be used to widen '0' and '1'. However, there was some
  discomfort about using such a heavyweight mechanism.  The proposed
  resolution allows those users who care about this issue to get it
  right.</p>
<p>We fix the inserter to use the new arguments.  Note that we already
  fixed the analogous problem with the extractor in issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#303">303</a>.</p>






<hr>
<h3><a name="397"></a>397. ostream::sentry dtor throws exceptions</h3>
<p><b>Section:</b> 27.6.2.4 [ostream::sentry] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-01-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#ostream::sentry">active issues</a> in [ostream::sentry].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#ostream::sentry">issues</a> in [ostream::sentry].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
    <p>
17.4.4.8, p3 prohibits library dtors from throwing exceptions.
    </p>
    <p>
27.6.2.3, p4 says this about the ostream::sentry dtor:
    </p>
    <pre>    -4- If ((os.flags() &amp; ios_base::unitbuf) &amp;&amp; !uncaught_exception())
        is true, calls os.flush().
    </pre>
    <p>
27.6.2.6, p7 that describes ostream::flush() says:
    </p>
    <pre>    -7- If rdbuf() is not a null pointer, calls rdbuf()-&gt;pubsync().
        If that function returns ?-1 calls setstate(badbit) (which
        may throw ios_base::failure (27.4.4.3)).
    </pre>
    <p>
That seems like a defect, since both pubsync() and setstate() can
throw an exception. 
    </p>
<p><i>[
The contradiction is real.  Clause 17 says destructors may never
throw exceptions, and clause 27 specifies a destructor that does
throw.  In principle we might change either one.  We're leaning
toward changing clause 17: putting in an "unless otherwise specified"
clause, and then putting in a footnote saying the sentry destructor
is the only one that can throw.  PJP suggests specifying that
sentry::~sentry() should internally catch any exceptions it might cause.
]</i></p>


<p><i>[
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#418">418</a> and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#622">622</a> for related issues.
]</i></p>


  

<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="398"></a>398. effects of end-of-file on unformatted input functions</h3>
<p><b>Section:</b> 27.6.2.4 [ostream::sentry] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-01-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#ostream::sentry">active issues</a> in [ostream::sentry].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#ostream::sentry">issues</a> in [ostream::sentry].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
    <p>
While reviewing unformatted input member functions of istream
for their behavior when they encounter end-of-file during input
I found that the requirements vary, sometimes unexpectedly, and
in more than one case even contradict established practice (GNU
libstdc++ 3.2, IBM VAC++ 6.0, STLPort 4.5, SunPro 5.3, HP aCC
5.38, Rogue Wave libstd 3.1, and Classic Iostreams).
    </p>
    <p>
The following unformatted input member functions set eofbit if they
encounter an end-of-file (this is the expected behavior, and also
the behavior of all major implementations):
    </p>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    get (char_type*, streamsize, char_type);
    </pre>
    <p>
    Also sets failbit if it fails to extract any characters.
    </p>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    get (char_type*, streamsize);
    </pre>
    <p>
    Also sets failbit if it fails to extract any characters.
    </p>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    getline (char_type*, streamsize, char_type);
    </pre>
    <p>
    Also sets failbit if it fails to extract any characters.
    </p>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    getline (char_type*, streamsize);
    </pre>
    <p>
    Also sets failbit if it fails to extract any characters.
    </p>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    ignore (int, int_type);
    </pre>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    read (char_type*, streamsize);
    </pre>
    <p>
    Also sets failbit if it encounters end-of-file.
    </p>
    <pre>    streamsize readsome (char_type*, streamsize);
    </pre>

    <p>
The following unformated input member functions set failbit but
not eofbit if they encounter an end-of-file (I find this odd
since the functions make it impossible to distinguish a general
failure from a failure due to end-of-file; the requirement is
also in conflict with all major implementation which set both
eofbit and failbit):
    </p>
    <pre>    int_type get();
    </pre>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    get (char_type&amp;);
    </pre>
    <p>
These functions only set failbit of they extract no characters,
otherwise they don't set any bits, even on failure (I find this
inconsistency quite unexpected; the requirement is also in
conflict with all major implementations which set eofbit
whenever they encounter end-of-file):
    </p>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    get (basic_streambuf&lt;charT, traits&gt;&amp;, char_type);
    </pre>
    <pre>    basic_istream&lt;charT, traits&gt;&amp;
    get (basic_streambuf&lt;charT, traits&gt;&amp;);
    </pre>
    <p>
This function sets no bits (all implementations except for
STLport and Classic Iostreams set eofbit when they encounter
end-of-file):
    </p>
    <pre>    int_type peek ();
    </pre>
<p>Informally, what we want is a global statement of intent saying
  that eofbit gets set if we trip across EOF, and then we can take
  away the specific wording for individual functions.  A full review
  is necessary.  The wording currently in the standard is a mishmash,
  and changing it on an individual basis wouldn't make things better.
  Dietmar will do this work.</p>
  

<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="408"></a>408. Is vector&lt;reverse_iterator&lt;char*&gt; &gt; forbidden?</h3>
<p><b>Section:</b> 24.1 [iterator.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Nathan Myers <b>Date:</b> 2003-06-03</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#iterator.requirements">active issues</a> in [iterator.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#iterator.requirements">issues</a> in [iterator.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I've been discussing iterator semantics with Dave Abrahams, and a 
surprise has popped up.  I don't think this has been discussed before.
</p>

<p>
24.1 [iterator.requirements] says that the only operation that can be performed on "singular"
iterator values is to assign a non-singular value to them.  (It 
doesn't say they can be destroyed, and that's probably a defect.)  
Some implementations have taken this to imply that there is no need 
to initialize the data member of a reverse_iterator&lt;&gt; in the default
constructor.  As a result, code like
</p>
<blockquote><pre>  std::vector&lt;std::reverse_iterator&lt;char*&gt; &gt; v(7);
  v.reserve(1000);
</pre></blockquote>
<p>
invokes undefined behavior, because it must default-initialize the
vector elements, and then copy them to other storage.  Of course many 
other vector operations on these adapters are also left undefined,
and which those are is not reliably deducible from the standard.
</p>

<p>
I don't think that 24.1 was meant to make standard-library iterator 
types unsafe.  Rather, it was meant to restrict what operations may 
be performed by functions which take general user- and standard 
iterators as arguments, so that raw pointers would qualify as
iterators.  However, this is not clear in the text, others have come 
to the opposite conclusion.
</p>

<p>
One question is whether the standard iterator adaptors have defined
copy semantics.  Another is whether they have defined destructor
semantics: is
</p>
<blockquote><pre>  { std::vector&lt;std::reverse_iterator&lt;char*&gt; &gt;  v(7); }
</pre></blockquote>
<p>
undefined too?
</p>

<p>
Note this is not a question of whether algorithms are allowed to
rely on copy semantics for arbitrary iterators, just whether the
types we actually supply support those operations.  I believe the 
resolution must be expressed in terms of the semantics of the 
adapter's argument type.  It should make clear that, e.g., the 
reverse_iterator&lt;T&gt; constructor is actually required to execute
T(), and so copying is defined if the result of T() is copyable.
</p>

<p>
Issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#235">235</a>, which defines reverse_iterator's default
constructor more precisely, has some relevance to this issue.
However, it is not the whole story.
</p>

<p>
The issue was whether 
</p>
<blockquote><pre>  reverse_iterator() { }
</pre></blockquote>
<p>
is allowed, vs. 
</p>
<blockquote><pre>  reverse_iterator() : current() { }
</pre></blockquote>

<p>
The difference is when T is char*, where the first leaves the member
uninitialized, and possibly equal to an existing pointer value, or
(on some targets) may result in a hardware trap when copied.
</p>

<p>
8.5 paragraph 5 seems to make clear that the second is required to
satisfy DR <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#235">235</a>, at least for non-class Iterator argument
types.
</p>

<p>
But that only takes care of reverse_iterator, and doesn't establish
a policy for all iterators.  (The reverse iterator adapter was just
an example.)  In particular, does my function
</p>
<blockquote><pre>  template &lt;typename Iterator&gt;
    void f() { std::vector&lt;Iterator&gt;  v(7); } 
</pre></blockquote>
<p>
evoke undefined behavior for some conforming iterator definitions?
I think it does, now, because vector&lt;&gt; will destroy those singular
iterator values, and that's explicitly disallowed.
</p>

<p>
24.1 shouldn't give blanket permission to copy all singular iterators,
because then pointers wouldn't qualify as iterators.  However, it
should allow copying of that subset of singular iterator values that
are default-initialized, and it should explicitly allow destroying any
iterator value, singular or not, default-initialized or not.
</p>

<p>Related issue: <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#407">407</a></p>
<p><i>[
We don't want to require all singular iterators to be copyable,
because that is not the case for pointers.  However, default
construction may be a special case.  Issue: is it really default
construction we want to talk about, or is it something like value
initialization?  We need to check with core to see whether default
constructed pointers are required to be copyable; if not, it would be
wrong to impose so strict a requirement for iterators.
]</i></p>




<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="417"></a>417. what does ctype::do_widen() return on failure</h3>
<p><b>Section:</b> 22.2.1.1.2 [locale.ctype.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.ctype.virtuals">issues</a> in [locale.ctype.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The Effects and Returns clauses of the do_widen() member function of
the ctype facet fail to specify the behavior of the function on failure.
That the function may not be able to simply cast the narrow character
argument to the type of the result since doing so may yield the wrong value
for some wchar_t encodings. Popular implementations of ctype&lt;wchar_t&gt; that
use mbtowc() and UTF-8 as the native encoding (e.g., GNU glibc) will fail
when the argument's MSB is set. There is no way for the the rest of locale
and iostream to reliably detect this failure. 
</p>
<p><i>[Kona: This is a real problem.  Widening can fail.  It's unclear
  what the solution should be.  Returning WEOF works for the wchar_t
  specialization, but not in general.  One option might be to add a
  default, like <i>narrow</i>.  But that's an incompatible change.
  Using <i>traits::eof</i> might seem like a good idea, but facets
  don't have access to traits (a recurring problem).  We could
  have <i>widen</i> throw an exception, but that's a scary option;
  existing library components aren't written with the assumption
  that <i>widen</i> can throw.]</i></p>



<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="418"></a>418. exceptions thrown during iostream cleanup</h3>
<p><b>Section:</b> 27.4.2.1.6 [ios::Init] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The dtor of the ios_base::Init object is supposed to call flush() on the
6 standard iostream objects cout, cerr, clog, wcout, wcerr, and wclog.
This call may cause an exception to be thrown.
</p>

<p>
17.4.4.8, p3 prohibits all library destructors from throwing exceptions.
</p>

<p>
The question is: What should this dtor do if one or more of these calls
to flush() ends up throwing an exception? This can happen quite easily
if one of the facets installed in the locale imbued in the iostream
object throws.
</p>
<p><i>[Kona: We probably can't do much better than what we've got, so
  the LWG is leaning toward NAD.  At the point where the standard
  stream objects are being cleaned up, the usual error reporting
  mechanism are all unavailable.  And exception from flush at this
  point will definitely cause problems.  A quality implementation
  might reasonably swallow the exception, or call abort, or do
  something even more drastic.]</i></p>


<p><i>[
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#397">397</a> and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#622">622</a> for related issues.
]</i></p>




<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="419"></a>419. istream extractors not setting failbit if eofbit is already set</h3>
<p><b>Section:</b> 27.6.1.1.3 [istream::sentry] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#istream::sentry">issues</a> in [istream::sentry].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

27.6.1.1.3 [istream::sentry], p2 says that istream::sentry ctor prepares for input if is.good()
is true. p4 then goes on to say that the ctor sets the sentry::ok_ member to
true if the stream state is good after any preparation. 27.6.1.2.1 [istream.formatted.reqmts], p1 then
says that a formatted input function endeavors to obtain the requested input
if the sentry's operator bool() returns true.

Given these requirements, no formatted extractor should ever set failbit if
the initial stream rdstate() == eofbit. That is contrary to the behavior of
all implementations I tested. The program below prints out

eof = 1, fail = 0
eof = 1, fail = 1

on all of them.
        </p>
<pre>
#include &lt;sstream&gt;
#include &lt;cstdio&gt;

int main()
{
    std::istringstream strm ("1");

    int i = 0;

    strm &gt;&gt; i;

    std::printf ("eof = %d, fail = %d\n",
                 !!strm.eof (), !!strm.fail ());

    strm &gt;&gt; i;

    std::printf ("eof = %d, fail = %d\n",
                 !!strm.eof (), !!strm.fail ());
}

</pre>
        <p>
<br>

Comments from Jerry Schwarz (c++std-lib-11373):
<br>

Jerry Schwarz wrote:
<br>

I don't know where (if anywhere) it says it in the standard, but the
formatted extractors are supposed to set failbit if they don't extract
any characters. If they didn't then simple loops like
<br>

while (cin &gt;&gt; x);
<br>

would loop forever.
<br>

Further comments from Martin Sebor:
<br>

The question is which part of the extraction should prevent this from happening
by setting failbit when eofbit is already set. It could either be the sentry
object or the extractor. It seems that most implementations have chosen to
set failbit in the sentry [...] so that's the text that will need to be
corrected. 

        </p>
<p>
Pre Berlin:  This issue is related to <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#342">342</a>.  If the sentry
sets <tt>failbit</tt> when it finds <tt>eofbit</tt> already set, then
you can never seek away from the end of stream.
</p>
<p>Kona: Possibly NAD.  If eofbit is set then good() will return false.  We
  then set <i>ok</i> to false.  We believe that the sentry's
  constructor should always set failbit when <i>ok</i> is false, and
  we also think the standard already says that.  Possibly it could be
  clearer.</p> 

    

<p><b>Proposed resolution:</b></p>
<p>
Change 27.6.1.1.3 [istream::sentry], p2 to:
</p>

<blockquote>
<pre>explicit sentry(basic_istream&lt;charT,traits&gt;&amp; <i>is</i> , bool <i>noskipws</i> = false);</pre>
<p>
-2- <i>Effects:</i> If <tt>is.good()</tt> is <del><tt>true</tt></del>
<ins><tt>false</tt></ins>, <ins>calls <tt>is.setstate(failbit)</tt>. 
Otherwise</ins> prepares for formatted or unformatted input. ...
</p>
</blockquote>






<hr>
<h3><a name="421"></a>421. is basic_streambuf copy-constructible?</h3>
<p><b>Section:</b> 27.5.2.1 [streambuf.cons] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#streambuf.cons">issues</a> in [streambuf.cons].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The reflector thread starting with c++std-lib-11346 notes that the class
template basic_streambuf, along with basic_stringbuf and basic_filebuf,
is copy-constructible but that the semantics of the copy constructors
are not defined anywhere. Further, different implementations behave
differently in this respect: some prevent copy construction of objects
of these types by declaring their copy ctors and assignment operators
private, others exhibit undefined behavior, while others still give
these operations well-defined semantics.
</p>

<p>
Note that this problem doesn't seem to be isolated to just the three
types mentioned above. A number of other types in the library section
of the standard provide a compiler-generated copy ctor and assignment
operator yet fail to specify their semantics.  It's believed that the
only types for which this is actually a problem (i.e. types where the
compiler-generated default may be inappropriate and may not have been
intended) are locale facets.  See issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#439">439</a>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
27.5.2 [lib.streambuf]:  Add into the synopsis, public section, just above the destructor declaration:
</p>

<blockquote>
<pre>basic_streambuf(const basic_streambuf&amp; sb);
basic_streambuf&amp; operator=(const basic_streambuf&amp; sb);
</pre>
</blockquote>

<p>Insert after 27.5.2.1, paragraph 2:</p>
<blockquote>
<pre>basic_streambuf(const basic_streambuf&amp; sb);
</pre>

<p>Constructs a copy of sb.</p>
<p>Postcondtions:</p>
<pre>                eback() == sb.eback()
                gptr()  == sb.gptr()
                egptr() == sb.egptr()
                pbase() == sb.pbase()
                pptr()  == sb.pptr()
                epptr() == sb.epptr()
                getloc() == sb.getloc()
</pre>

<pre>basic_streambuf&amp; operator=(const basic_streambuf&amp; sb);
</pre>

<p>Assigns the data members of sb to this.</p>

<p>Postcondtions:</p>
<pre>                eback() == sb.eback()
                gptr()  == sb.gptr()
                egptr() == sb.egptr()
                pbase() == sb.pbase()
                pptr()  == sb.pptr()
                epptr() == sb.epptr()
                getloc() == sb.getloc()
</pre>

<p>Returns: *this.</p>
</blockquote>

<p>27.7.1 [lib.stringbuf]:</p>

<p><b>Option A:</b></p>

<blockquote>
<p>Insert into the basic_stringbuf synopsis in the private section:</p>

<pre>basic_stringbuf(const basic_stringbuf&amp;);             // not defined
basic_stringbuf&amp; operator=(const basic_stringbuf&amp;);  // not defined
</pre>
</blockquote>

<p><b>Option B:</b></p>

<blockquote>
<p>Insert into the basic_stringbuf synopsis in the public section:</p>

<pre>basic_stringbuf(const basic_stringbuf&amp; sb);
basic_stringbuf&amp; operator=(const basic_stringbuf&amp; sb);
</pre>

<p>27.7.1.1, insert after paragraph 4:</p>

<pre>basic_stringbuf(const basic_stringbuf&amp; sb);</pre>

<p>
Constructs an independent copy of sb as if with sb.str(), and with the openmode that sb was constructed with.
</p>

<p>Postcondtions: </p>
<pre>               str() == sb.str()
               gptr()  - eback() == sb.gptr()  - sb.eback()
               egptr() - eback() == sb.egptr() - sb.eback()
               pptr()  - pbase() == sb.pptr()  - sb.pbase()
               getloc() == sb.getloc()
</pre>

<p>
Note: The only requirement on epptr() is that it point beyond the
initialized range if an output sequence exists. There is no requirement
that epptr() - pbase() == sb.epptr() - sb.pbase().
</p>

<pre>basic_stringbuf&amp; operator=(const basic_stringbuf&amp; sb);</pre>
<p>After assignment the basic_stringbuf has the same state as if it
were initially copy constructed from sb, except that the
basic_stringbuf is allowed to retain any excess capacity it might have,
which may in turn effect the value of epptr().
</p>
</blockquote>

<p>27.8.1.1 [lib.filebuf]</p>

<p>Insert at the bottom of the basic_filebuf synopsis:</p>

<blockquote>
<pre>private:
  basic_filebuf(const basic_filebuf&amp;);             // not defined
  basic_filebuf&amp; operator=(const basic_filebuf&amp;);  // not defined
</pre>
</blockquote>
<p><i>[Kona: this is an issue for basic_streambuf itself and for its
  derived classes.  We are leaning toward allowing basic_streambuf to
  be copyable, and specifying its precise semantics.  (Probably the
  obvious: copying the buffer pointers.)  We are less sure whether
  the streambuf derived classes should be copyable.  Howard will
  write up a proposal.]</i></p>


<p><i>[Sydney: Dietmar presented a new argument against basic_streambuf
  being copyable: it can lead to an encapsulation violation. Filebuf
  inherits from streambuf. Now suppose you inhert a my_hijacking_buf
  from streambuf. You can copy the streambuf portion of a filebuf to a
  my_hijacking_buf, giving you access to the pointers into the
  filebuf's internal buffer. Perhaps not a very strong argument, but
  it was strong enough to make people nervous. There was weak
  preference for having streambuf not be copyable. There was weak
  preference for having stringbuf not be copyable even if streambuf
  is. Move this issue to open for now.
]</i></p>


<p><i>[
2007-01-12, Howard:
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1862.html#27.5.2%20-%20Class%20template%20basic_streambuf%3CcharT,traits%3E">Rvalue Reference Recommendations for Chapter 27</a>
recommends protected copy constructor and assignment for <tt>basic_streambuf</tt> with the same semantics
as would be generated by the compiler.  These members aid in derived classes implementing move semantics.
A protected copy constructor and copy assignment operator do not expose encapsulation more so than it is
today as each data member of a <tt>basic_streambuf</tt> is already both readable and writable by derived
classes via various get/set protected member functions (<tt>eback()</tt>, <tt>setp()</tt>, etc.).  Rather
a protected copy constructor and copy assignment operator simply make the job of derived classes implementing
move semantics less tedious and error prone.
]</i></p>




<p><b>Rationale:</b></p>
<p>
27.5.2 [lib.streambuf]: The proposed basic_streambuf copy constructor
and assignment operator are the same as currently implied by the lack
of declarations: public and simply copies the data members.  This
resolution is not a change but a clarification of the current
standard.
</p>

<p>
27.7.1 [lib.stringbuf]: There are two reasonable options: A) Make
basic_stringbuf not copyable.  This is likely the status-quo of
current implementations.  B) Reasonable copy semantics of
basic_stringbuf can be defined and implemented.  A copyable
basic_streambuf is arguably more useful than a non-copyable one.  This
should be considered as new functionality and not the fixing of a
defect.  If option B is chosen, ramifications from issue 432 are taken
into account.
</p>

<p>
27.8.1.1 [lib.filebuf]: There are no reasonable copy semantics for
basic_filebuf.
</p>






<hr>
<h3><a name="423"></a>423. effects of negative streamsize in iostreams</h3>
<p><b>Section:</b> 27 [input.output] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#input.output">issues</a> in [input.output].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>

<p>
A third party test suite tries to exercise istream::ignore(N) with
a negative value of N and expects that the implementation will treat
N as if it were 0. Our implementation asserts that (N &gt;= 0) holds and
aborts the test.
</p>

<p>
I can't find anything in section 27 that prohibits such values but I don't
see what the effects of such calls should be, either (this applies to
a number of unformatted input functions as well as some member functions
of the basic_streambuf template).
</p>


<p><b>Proposed resolution:</b></p>
<p>
I propose that we add to each function in clause 27 that takes an argument,
say N, of type streamsize a Requires clause saying that "N &gt;= 0." The intent
is to allow negative streamsize values in calls to precision() and width()
but disallow it in calls to streambuf::sgetn(), istream::ignore(), or
ostream::write().
</p>

<p><i>[Kona: The LWG agreed that this is probably what we want.  However, we
  need a review to find all places where functions in clause 27 take
  arguments of type streamsize that shouldn't be allowed to go
  negative.  Martin will do that review.]</i></p>






<hr>
<h3><a name="424"></a>424. normative notes</h3>
<p><b>Section:</b> 17.3.1.1 [structure.summary] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>

<p>
The text in 17.3.1.1, p1 says:
<br>

"Paragraphs labelled "Note(s):" or "Example(s):" are informative, other
paragraphs are normative."
<br>

The library section makes heavy use of paragraphs labeled "Notes(s),"
some of which are clearly intended to be normative (see list 1), while
some others are not (see list 2). There are also those where the intent
is not so clear (see list 3).
<br><br>

List 1 -- Examples of (presumably) normative Notes:
<br>

20.6.1.1 [allocator.members], p3,<br>
20.6.1.1 [allocator.members], p10,<br>
21.3.2 [string.cons], p11,<br>
22.1.1.2 [locale.cons], p11,<br>
23.2.2.3 [deque.modifiers], p2,<br>
25.3.7 [alg.min.max], p3,<br>
26.3.6 [complex.ops], p15,<br>
27.5.2.4.3 [streambuf.virt.get], p7.<br>
<br>

List 2 -- Examples of (presumably) informative Notes:
<br>

18.5.1.3 [new.delete.placement], p3,<br>
21.3.6.6 [string::replace], p14,<br>
22.2.1.4.2 [locale.codecvt.virtuals], p3,<br>
25.1.1 [alg.foreach], p4,<br>
26.3.5 [complex.member.ops], p1,<br>
27.4.2.5 [ios.base.storage], p6.<br>
<br>

List 3 -- Examples of Notes that are not clearly either normative
or informative:
<br>

22.1.1.2 [locale.cons], p8,<br>
22.1.1.5 [locale.statics], p6,<br>
27.5.2.4.5 [streambuf.virt.put], p4.<br>
<br>

None of these lists is meant to be exhaustive.
</p>

<p><i>[Definitely a real problem.  The big problem is there's material
  that doesn't quite fit any of the named paragraph categories
  (e.g. <b>Effects</b>).  Either we need a new kind of named
  paragraph, or we need to put more material in unnamed paragraphs
  jsut after the signature.  We need to talk to the Project Editor
  about how to do this.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p><i>[Pete: I changed the paragraphs marked "Note" and "Notes" to use "Remark" and "Remarks".
Fixed as editorial.  This change has been in the WD since the post-Redmond mailing, in 2004.
Recommend NAD.]</i></p>

<p><i>[
Batavia:  We feel that the references in List 2 above should be changed from <i>Remarks</i>
to <i>Notes</i>.  We also feel that those items in List 3 need to be double checked for
the same change.  Alan and Pete to review.
]</i></p>





<hr>
<h3><a name="427"></a>427. stage 2 and rationale of DR 221</h3>
<p><b>Section:</b> 22.2.2.1.2 [facet.num.get.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#facet.num.get.virtuals">active issues</a> in [facet.num.get.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#facet.num.get.virtuals">issues</a> in [facet.num.get.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The requirements specified in Stage 2 and reiterated in the rationale
of DR 221 (and echoed again in DR 303) specify that num_get&lt;charT&gt;::
do_get() compares characters on the stream against the widened elements
of "012...abc...ABCX+-"
</p>

<p>
An implementation is required to allow programs to instantiate the num_get
template on any charT that satisfies the requirements on a user-defined
character type. These requirements do not include the ability of the
character type to be equality comparable (the char_traits template must
be used to perform tests for equality). Hence, the num_get template cannot
be implemented to support any arbitrary character type. The num_get template
must either make the assumption that the character type is equality-comparable
(as some popular implementations do), or it may use char_traits&lt;charT&gt; to do
the comparisons (some other popular implementations do that). This diversity
of approaches makes it difficult to write portable programs that attempt to
instantiate the num_get template on user-defined types.
</p>

<p><i>[Kona: the heart of the problem is that we're theoretically
  supposed to use traits classes for all fundamental character
  operations like assignment and comparison, but facets don't have
  traits parameters.  This is a fundamental design flaw and it
  appears all over the place, not just in this one place.  It's not
  clear what the correct solution is, but a thorough review of facets
  and traits is in order.  The LWG considered and rejected the
  possibility of changing numeric facets to use narrowing instead of
  widening.  This may be a good idea for other reasons (see issue
  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#459">459</a>), but it doesn't solve the problem raised by this
  issue.  Whether we use widen or narrow the <tt>num_get</tt> facet
  still has no idea which traits class the user wants to use for 
  the comparison, because only streams, not facets, are passed traits
  classes.   The standard does not require that two different
  traits classes with the same <tt>char_type</tt> must necessarily 
  have the same behavior.]</i></p>


<p>Informally, one possibility: require that some of the basic
character operations, such as <tt>eq</tt>, <tt>lt</tt>,
and <tt>assign</tt>, must behave the same way for all traits classes
with the same <tt>char_type</tt>.  If we accept that limitation on
traits classes, then the facet could reasonably be required to
use <tt>char_traits&lt;charT&gt;</tt>.</p>


<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="430"></a>430. valarray subset operations</h3>
<p><b>Section:</b> 26.5.2.4 [valarray.sub] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2003-09-18</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The standard fails to specify the behavior of valarray::operator[](slice)
and other valarray subset operations when they are passed an "invalid"
slice object, i.e., either a slice that doesn't make sense at all (e.g.,
slice (0, 1, 0) or one that doesn't specify a valid subset of the valarray
object (e.g., slice (2, 1, 1) for a valarray of size 1).
</p>
<p><i>[Kona: the LWG believes that invalid slices should invoke
  undefined behavior.  Valarrays are supposed to be designed for high
  performance, so we don't want to require specific checking.  We
  need wording to express this decision.]</i></p>



<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="431"></a>431. Swapping containers with unequal allocators</h3>
<p><b>Section:</b> 20.1.2 [allocator.requirements], 25 [algorithms] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Matt Austern <b>Date:</b> 2003-09-20</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#allocator.requirements">active issues</a> in [allocator.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#allocator.requirements">issues</a> in [allocator.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>Clause 20.1.2 [allocator.requirements] paragraph 4 says that implementations
  are permitted to supply containers that are unable to cope with
  allocator instances and that container implementations may assume
  that all instances of an allocator type compare equal.  We gave
  implementers this latitude as a temporary hack, and eventually we
  want to get rid of it.  What happens when we're dealing with
  allocators that <i>don't</i> compare equal?
</p>

<p>In particular: suppose that <tt>v1</tt> and <tt>v2</tt> are both
  objects of type <tt>vector&lt;int, my_alloc&gt;</tt> and that
  <tt>v1.get_allocator() != v2.get_allocator()</tt>.  What happens if
  we write <tt>v1.swap(v2)</tt>?  Informally, three possibilities:</p>

<p>1. This operation is illegal.  Perhaps we could say that an
  implementation is required to check and to throw an exception, or
  perhaps we could say it's undefined behavior.</p>
<p>2. The operation performs a slow swap (i.e. using three
  invocations of <tt>operator=</tt>, leaving each allocator with its
  original container.  This would be an O(N) operation.</p>
<p>3. The operation swaps both the vectors' contents and their
  allocators.  This would be an O(1) operation. That is:</p>
  <blockquote>
  <pre>    my_alloc a1(...);
    my_alloc a2(...);
    assert(a1 != a2);

    vector&lt;int, my_alloc&gt; v1(a1);
    vector&lt;int, my_alloc&gt; v2(a2);
    assert(a1 == v1.get_allocator());
    assert(a2 == v2.get_allocator());

    v1.swap(v2);
    assert(a1 == v2.get_allocator());
    assert(a2 == v1.get_allocator());
  </pre>
  </blockquote>

<p><i>[Kona: This is part of a general problem.  We need a paper
  saying how to deal with unequal allocators in general.]</i></p>


<p><i>[pre-Sydney: Howard argues for option 3 in
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1599.html">N1599</a>.
]</i></p>


<p><i>[
2007-01-12, Howard:  This issue will now tend to come up more often with move constructors
and move assignment operators.  For containers, these members transfer resources (i.e.
the allocated memory) just like swap.
]</i></p>


<p><i>[
Batavia:  There is agreement to overload the container <tt>swap</tt> on the allocator's Swappable
requirement using concepts.  If the allocator supports Swappable, then container's swap will
swap allocators, else it will perform a "slow swap" using copy construction and copy assignment.
]</i></p>




<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="446"></a>446. Iterator equality between different containers</h3>
<p><b>Section:</b> 24.1 [iterator.requirements], 23.1 [container.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Andy Koenig <b>Date:</b> 2003-12-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#iterator.requirements">active issues</a> in [iterator.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#iterator.requirements">issues</a> in [iterator.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
What requirements does the standard place on equality comparisons between
iterators that refer to elements of different containers.  For example, if
v1 and v2 are empty vectors, is v1.end() == v2.end() allowed to yield true?
Is it allowed to throw an exception?
</p>

<p>
The standard appears to be silent on both questions.
</p>
<p><i>[Sydney: The intention is that comparing two iterators from
different containers is undefined, but it's not clear if we say that,
or even whether it's something we should be saying in clause 23 or in
clause 24.  Intuitively we might want to say that equality is defined
only if one iterator is reachable from another, but figuring out how
to say it in any sensible way is a bit tricky: reachability is defined
in terms of equality, so we can't also define equality in terms of
reachability.
]</i></p>




<p><b>Proposed resolution:</b></p>






<hr>
<h3><a name="454"></a>454. basic_filebuf::open should accept wchar_t names</h3>
<p><b>Section:</b> 27.8.1.4 [filebuf.members] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Bill Plauger <b>Date:</b> 2004-01-30</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#filebuf.members">active issues</a> in [filebuf.members].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#filebuf.members">issues</a> in [filebuf.members].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<pre>    basic_filebuf *basic_filebuf::open(const char *, ios_base::open_mode);
</pre>

<p>should be supplemented with the overload:</p>

<pre>    basic_filebuf *basic_filebuf::open(const wchar_t *, ios_base::open_mode);
</pre>

<p>
Depending on the operating system, one of these forms is fundamental and
the other requires an implementation-defined mapping to determine the
actual filename.
</p>

<p><i>[Sydney: Yes, we want to allow wchar_t filenames.  Bill will
  provide wording.]</i></p>


<p><i>[
In Toronto we noted that this is issue 5 from
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1569.htm">N1569</a>.
]</i></p>

<p>
How does this interact with the newly-defined character types, and how
do we avoid interface explosion considering <tt>std::string</tt> overloads that
were added? Propose another solution that is different than the
suggestion proposed by PJP.
</p>
<p>
Suggestion is to make a member template function for <tt>basic_string</tt> (for
<tt>char</tt>, <tt>wchar_t</tt>, <tt>u16char</tt>, <tt>u32char</tt> instantiations), and then just keep a
<tt>const char*</tt> member.
</p>
<p>
Goal is to do implicit conversion between character string literals to
appropriate <tt>basic_string</tt> type. Not quite sure if this is possible.
</p>
<p>
Implementors are free to add specific overloads for non-char character
types.
</p>



<p><b>Proposed resolution:</b></p>

<p>Change from:</p>
<blockquote>
<pre>basic_filebuf&lt;charT,traits&gt;* open(
	const char* s,
	ios_base::openmode mode );
</pre>

<p>
Effects: If is_open() != false, returns a null pointer.
Otherwise, initializes the filebuf as required. It then
opens a file, if possible, whose name is the NTBS s ("as if"
by calling std::fopen(s,modstr)).</p>
</blockquote>

<p>to:</p>

<blockquote>
<pre>basic_filebuf&lt;charT,traits&gt;* open(
	const char* s,
	ios_base::openmode mode );

basic_filebuf&lt;charT,traits&gt;* open(
	const wchar_t* ws,
	ios_base::openmode mode );
</pre>

<p>
Effects: If is_open() != false, returns a null pointer.
Otherwise, initializes the filebuf as required. It then
opens a file, if possible, whose name is the NTBS s ("as if"
by calling std::fopen(s,modstr)).
For the second signature, the NTBS s is determined from the
WCBS ws in an implementation-defined manner.
</p>

<p>
(NOTE: For a system that "naturally" represents a filename
as a WCBS, the NTBS s in the first signature may instead
be mapped to a WCBS; if so, it follows the same mapping
rules as the first argument to open.)
</p>
</blockquote>



<p><b>Rationale:</b></p>
<p>
Slightly controversial, but by a 7-1 straw poll the LWG agreed to move
this to Ready.  The controversy was because the mapping between wide
names and files in a filesystem is implementation defined.  The
counterargument, which most but not all LWG members accepted, is that
the mapping between narrow files names and files is also
implemenation defined.</p>

<p><i>[Lillehammer: Moved back to "open" status, at Beman's urging.
(1) Why just basic_filebuf, instead of also basic_fstream (and
possibly other things too). (2) Why not also constructors that take
std::basic_string? (3) We might want to wait until we see Beman's
filesystem library; we might decide that it obviates this.]</i></p>









<hr>
<h3><a name="458"></a>458. 24.1.5 contains unintented limitation for operator-</h3>
<p><b>Section:</b> 24.1.5 [random.access.iterators] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Daniel Frey <b>Date:</b> 2004-02-27</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#random.access.iterators">issues</a> in [random.access.iterators].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In 24.1.5 [lib.random.access.iterators], table 76 the operational
semantics for the expression "r -= n" are defined as "return r += -n".
This means, that the expression -n must be valid, which is not the case
for unsigned types. 
</p>

<p><i>[
Sydney: Possibly not a real problem, since difference type is required
to be a signed integer type. However, the wording in the standard may
be less clear than we would like.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
To remove this limitation, I suggest to change the
operational semantics for this column to:
</p>
<blockquote><pre>    { Distance m = n; 
      if (m &gt;= 0) 
        while (m--) --r; 
      else 
        while (m++) ++r;
      return r; }
</pre></blockquote>






<hr>
<h3><a name="459"></a>459. Requirement for widening in stage 2 is overspecification</h3>
<p><b>Section:</b> 22.2.2.1.2 [facet.num.get.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2004-03-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#facet.num.get.virtuals">active issues</a> in [facet.num.get.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#facet.num.get.virtuals">issues</a> in [facet.num.get.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>When parsing strings of wide-character digits, the standard
  requires the library to widen narrow-character "atoms" and compare
  the widened atoms against the characters that are being parsed.
  Simply narrowing the wide characters would be far simpler, and
  probably more efficient.  The two choices are equivalent except in
  convoluted test cases, and many implementations already ignore the
  standard and use narrow instead of widen.</p>

<p>
First, I disagree that using narrow() instead of widen() would
necessarily have unfortunate performance implications. A possible
implementation of narrow() that allows num_get to be implemented
in a much simpler and arguably comparably efficient way as calling
widen() allows, i.e. without making a virtual call to do_narrow every
time, is as follows:
</p>

<pre>  inline char ctype&lt;wchar_t&gt;::narrow (wchar_t wc, char dflt) const
  {
      const unsigned wi = unsigned (wc);

      if (wi &gt; UCHAR_MAX)
          return typeid (*this) == typeid (ctype&lt;wchar_t&gt;) ?
                 dflt : do_narrow (wc, dflt);

      if (narrow_ [wi] &lt; 0) {
         const char nc = do_narrow (wc, dflt);
         if (nc == dflt)
             return dflt;
         narrow_ [wi] = nc;
      }

      return char (narrow_ [wi]);
  }
</pre>

<p>
Second, I don't think the change proposed in the issue (i.e., to use
narrow() instead of widen() during Stage 2) would be at all
drastic. Existing implementations with the exception of libstdc++
currently already use narrow() so the impact of the change on programs
would presumably be isolated to just a single implementation. Further,
since narrow() is not required to translate alternate wide digit
representations such as those mentioned in issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#303">303</a>
to
their narrow equivalents (i.e., the portable source characters '0'
through '9'), the change does not necessarily imply that these
alternate digits would be treated as ordinary digits and accepted as
part of numbers during parsing. In fact, the requirement in 22.2.1.1.2
[locale.ctype.virtuals], p13 forbids narrow() to translate an alternate
digit character, wc, to an ordinary digit in the basic source
character set unless the expression
(ctype&lt;charT&gt;::is(ctype_base::digit, wc) == true) holds. This in
turn is prohibited by the C standard (7.25.2.1.5, 7.25.2.1.5, and
5.2.1, respectively) for charT of either char or wchar_t.
</p>

<p><i>[Sydney: To a large extent this is a nonproblem. As long as
you're only trafficking in char and wchar_t we're only dealing with a
stable character set, so you don't really need either 'widen' or
'narrow': can just use literals. Finally, it's not even clear whether
widen-vs-narrow is the right question; arguably we should be using
codecvt instead.]</i></p>




<p><b>Proposed resolution:</b></p>
<p>Change stage 2 so that implementations are permitted to use either
technique to perform the comparison:</p>
<ol>
  <li> call widen on the atoms and compare (either by using
      operator== or char_traits&lt;charT&gt;::eq) the input with
      the widened atoms, or</li>
  <li> call narrow on the input and compare the narrow input
      with the atoms</li>
  <li> do (1) or (2) only if charT is not char or wchar_t,
      respectively; i.e., avoid calling widen or narrow
      if it the source and destination types are the same</li>
</ol>





<hr>
<h3><a name="462"></a>462. Destroying objects with static storage duration</h3>
<p><b>Section:</b> 3.6.3 [basic.start.term], 18.3 [cstdint] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Bill Plauger <b>Date:</b> 2004-03-23</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
3.6.3 Termination spells out in detail the interleaving of static
destructor calls and calls to functions registered with atexit. To
match this behavior requires intimate cooperation between the code
that calls destructors and the exit/atexit machinery. The former
is tied tightly to the compiler; the latter is a primitive mechanism
inherited from C that traditionally has nothing to do with static
construction and destruction. The benefits of intermixing destructor
calls with atexit handler calls is questionable at best, and <i>very</i>
difficult to get right, particularly when mixing third-party C++
libraries with different third-party C++ compilers and C libraries
supplied by still other parties.
</p>

<p>
I believe the right thing to do is defer all static destruction
until after all atexit handlers are called. This is a change in
behavior, but one that is likely visible only to perverse test
suites. At the very least, we should <i>permit</i> deferred destruction
even if we don't require it.
</p>

<p><i>[If this is to be changed, it should probably be changed by CWG.
  At this point, however, the LWG is leaning toward NAD.  Implementing
  what the standard says is hard work, but it's not impossible and
  most vendors went through that pain years ago.  Changing this
  behavior would be a user-visible change, and would break at least
  one real application.]</i></p>


<p><i>[
Batavia:  Send to core with our recommendation that we should permit deferred
destruction but not require it.
]</i></p>


<p><i>[
Howard:  The course of action recommended in Batavia would undo LWG
issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#3">3</a> and break current code implementing the "phoenix
singleton". Search the net for "phoenix singleton atexit" to get a feel
for the size of the adverse impact this change would have.  Below is
sample code which implements the phoenix singleton and would break if
<tt>atexit</tt> is changed in this way:
]</i></p>


<blockquote><pre>#include &lt;cstdlib&gt;
#include &lt;iostream&gt;
#include &lt;type_traits&gt;
#include &lt;new&gt;

class A
{
    bool alive_;
    A(const A&amp;);
    A&amp; operator=(const A&amp;);
public:
    A() : alive_(true) {std::cout &lt;&lt; "A()\n";}
    ~A() {alive_ = false; std::cout &lt;&lt; "~A()\n";}
    void use()
    {
        if (alive_)
            std::cout &lt;&lt; "A is alive\n";
        else
            std::cout &lt;&lt; "A is dead\n";
    }
};

void deallocate_resource();

// This is the phoenix singleton pattern
A&amp; get_resource(bool create = true)
{
    static std::aligned_storage&lt;sizeof(A), std::alignment_of&lt;A&gt;::value&gt;::type buf;
    static A* a;
    if (create)
    {
        if (a != (A*)&amp;buf)
        {
            a = ::new (&amp;buf) A;
            std::atexit(deallocate_resource);
        }
    }
    else
    {
        a-&gt;~A();
        a = (A*)&amp;buf + 1;
    }
    return *a;
}

void deallocate_resource()
{
    get_resource(false);
}

void use_A(const char* message)
{
    A&amp; a = get_resource();
    std::cout &lt;&lt; "Using A " &lt;&lt; message &lt;&lt; "\n";
    a.use();
}

struct B
{
    ~B() {use_A("from ~B()");}
};

B b;

int main()
{
    use_A("from main()");
}
</pre></blockquote>

<p>
The correct output is:
</p>

<blockquote><pre>A()
Using A from main()
A is alive
~A()
A()
Using A from ~B()
A is alive
~A()
</pre></blockquote>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="471"></a>471. result of what() implementation-defined</h3>
<p><b>Section:</b> 18.6.1 [type.info] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2004-06-28</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#type.info">issues</a> in [type.info].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>

<p>[lib.exception] specifies the following:</p>
<pre>    exception (const exception&amp;) throw();
    exception&amp; operator= (const exception&amp;) throw();

    -4- Effects: Copies an exception object.
    -5- Notes: The effects of calling what() after assignment
        are implementation-defined.
</pre>

<p>
First, does the Note only apply to the assignment operator? If so,
what are the effects of calling what() on a copy of an object? Is
the returned pointer supposed to point to an identical copy of
the NTBS returned by what() called on the original object or not?
</p>

<p>
Second, is this Note intended to extend to all the derived classes
in section 19? I.e., does the standard provide any guarantee for
the effects of what() called on a copy of any of the derived class
described in section 19?
</p>

<p>
Finally, if the answer to the first question is no, I believe it
constitutes a defect since throwing an exception object typically
implies invoking the copy ctor on the object. If the answer is yes,
then I believe the standard ought to be clarified to spell out
exactly what the effects are on the copy (i.e., after the copy
ctor was called).
</p>

<p><i>[Redmond: Yes, this is fuzzy.  The issue of derived classes is
  fuzzy too.]</i></p>


<p><i>[
Batavia: Howard provided wording.
]</i></p>




<p><b>Proposed resolution:</b></p>

<p>
Change 18.7.1 [exception] to:
</p>

<blockquote>
<pre>exception(const exception&amp; <ins><i>e</i></ins>) throw();
exception&amp; operator=(const exception&amp; <ins><i>e</i></ins>) throw();</pre>
<blockquote>
<p>
-4- <i>Effects:</i> Copies an exception object.
</p>
<p>
<del> -5- <i>Remarks:</i> The effects of calling what() after assignment are implementation-defined.</del>
</p>
<p>
<ins>-5- <i>Throws:</i> Nothing.  This also applies
to all standard library-defined classes that derive from <tt>exception</tt>.</ins>
</p>
<p>
<ins>-7- <i>Postcondition:</i> <tt>strcmp(what(), <i>e</i>.what()) == 0</tt>.  This also applies
to all standard library-defined classes that derive from <tt>exception</tt>.</ins>
</p>

</blockquote>
</blockquote>




<hr>
<h3><a name="473"></a>473. underspecified ctype calls</h3>
<p><b>Section:</b> 22.2.1.1 [locale.ctype] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2004-07-01</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Most ctype member functions come in two forms: one that operates
on a single character at a time and another form that operates
on a range of characters. Both forms are typically described by
a single Effects and/or Returns clause.
</p>
<p>
The Returns clause of each of the single-character non-virtual forms
suggests that the function calls the corresponding single character
virtual function, and that the array form calls the corresponding
virtual array form. Neither of the two forms of each virtual member
function is required to be implemented in terms of the other.
</p>
<p>
There are three problems:
</p>
<p>
1. One is that while the standard does suggest that each non-virtual
member function calls the corresponding form of the virtual function,
it doesn't actually explicitly require it.
</p>
<p>
Implementations that cache results from some of the virtual member
functions for some or all values of their arguments might want to
call the array form from the non-array form the first time to fill
the cache and avoid any or most subsequent virtual calls. Programs
that rely on each form of the virtual function being called from
the corresponding non-virtual function will see unexpected behavior
when using such implementations.
</p>
<p>
2. The second problem is that either form of each of the virtual
functions can be overridden by a user-defined function in a derived
class to return a value that is different from the one produced by
the virtual function of the alternate form that has not been
overriden.
</p>
<p>
Thus, it might be possible for, say, ctype::widen(c) to return one
value, while for ctype::widen(&amp;c, &amp;c + 1, &amp;wc) to set
wc to another value. This is almost certainly not intended. Both
forms of every function should be required to return the same result
for the same character, otherwise the same program using an
implementation that calls one form of the functions will behave
differently than when using another implementation that calls the
other form of the function "under the hood."
</p>
<p>
3. The last problem is that the standard text fails to specify whether
one form of any of the virtual functions is permitted to be implemented
in terms of the other form or not, and if so, whether it is required
or permitted to call the overridden virtual function or not.
</p>
<p>
Thus, a program that overrides one of the virtual functions so that
it calls the other form which then calls the base member might end
up in an infinite loop if the called form of the base implementation
of the function in turn calls the other form.
</p>
<p>
Lillehammer: Part of this isn't a real problem. We already talk about
caching. 22.1.1/6 But part is a real problem. ctype virtuals may call
each other, so users don't know which ones to override to avoid avoid
infinite loops.</p>

<p>This is a problem for all facet virtuals, not just ctype virtuals,
so we probably want a blanket statement in clause 22 for all
facets. The LWG is leaning toward a blanket prohibition, that a
facet's virtuals may never call each other. We might want to do that
in clause 27 too, for that matter. A review is necessary.  Bill will
provide wording.</p>


<p><b>Proposed resolution:</b></p>




<hr>
<h3><a name="484"></a>484. Convertible to T</h3>
<p><b>Section:</b> 24.1.1 [input.iterators] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Chris Jefferson <b>Date:</b> 2004-09-16</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#input.iterators">issues</a> in [input.iterators].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>From comp.std.c++:</p>

<p>
I note that given an input iterator a for type T, 
then *a only has to be "convertable to T", not actually of type T.
</p>

<p>Firstly, I can't seem to find an exact definition of "convertable to T". 
While I assume it is the obvious definition (an implicit conversion), I 
can't find an exact definition. Is there one?</p>

<p>Slightly more worryingly, there doesn't seem to be any restriction on 
the this type, other than it is "convertable to T". Consider two input 
iterators a and b. I would personally assume that most people would 
expect *a==*b would perform T(*a)==T(*b), however it doesn't seem that 
the standard requires that, and that whatever type *a is (call it U) 
could have == defined on it with totally different symantics and still 
be a valid inputer iterator.</p>

<p>Is this a correct reading? When using input iterators should I write 
T(*a) all over the place to be sure that the object i'm using is the 
class I expect?</p>

<p>This is especially a nuisance for operations that are defined to be
  "convertible to bool".  (This is probably allowed so that
  implementations could return say an int and avoid an unnessary
  conversion. However all implementations I have seen simply return a
  bool anyway.  Typical implemtations of STL algorithms just write
  things like <tt>while(a!=b &amp;&amp; *a!=0)</tt>.  But strictly
  speaking, there are lots of types that are convertible to T but
  that also overload the appropriate operators so this doesn't behave
  as expected.</p>

<p>If we want to make code like this legal (which most people seem to
  expect), then we'll need to tighten up what we mean by "convertible
  to T".</p>

<p><i>[Lillehammer: The first part is NAD, since "convertible" is
 well-defined in core. The second part is basically about pathological
 overloads. It's a minor problem but a real one. So leave open for
 now, hope we solve it as part of iterator redesign.]</i></p>



<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="485"></a>485. output iterator insufficently constrained</h3>
<p><b>Section:</b> 24.1.2 [output.iterators] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Chris Jefferson <b>Date:</b> 2004-10-13</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#output.iterators">issues</a> in [output.iterators].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The note on 24.1.2 Output iterators insufficently limits what can be
performed on output iterators. While it requires that each iterator is
progressed through only once and that each iterator is written to only
once, it does not require the following things:</p>

<p>Note: Here it is assumed that x is an output iterator of type X which
has not yet been assigned to.</p>

<p>a) That each value of the output iterator is written to:
The standard allows:
++x; ++x; ++x;
</p>

<p>
b) That assignments to the output iterator are made in order
X a(x); ++a; *a=1; *x=2; is allowed
</p>

<p>
c) Chains of output iterators cannot be constructed:
X a(x); ++a; X b(a); ++b; X c(b); ++c; is allowed, and under the current
wording (I believe) x,a,b,c could be written to in any order.
</p>

<p>I do not believe this was the intension of the standard?</p>
<p><i>[Lillehammer: Real issue.  There are lots of constraints we
  intended but didn't specify.  Should be solved as part of iterator
  redesign.]</i></p>



<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="492"></a>492. Invalid iterator arithmetic expressions</h3>
<p><b>Section:</b> 23 [containers], 24 [iterators], 25 [algorithms] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Thomas Mang <b>Date:</b> 2004-12-12</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#containers">issues</a> in [containers].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>Various clauses other than clause 25 make use of iterator arithmetic not
supported by the iterator category in question.
Algorithms in clause 25 are exceptional because of 25 [lib.algorithms],
paragraph 9, but this paragraph does not provide semantics to the
expression "iterator - n", where n denotes a value of a distance type
between iterators.</p>

<p>1) Examples of current wording:</p>

<p>Current wording outside clause 25:</p>

<p>
23.2.2.4 [lib.list.ops], paragraphs 19-21: "first + 1", "(i - 1)",
"(last - first)"
23.3.1.1 [lib.map.cons], paragraph 4: "last - first"
23.3.2.1 [lib.multimap.cons], paragraph 4: "last - first"
23.3.3.1 [lib.set.cons], paragraph 4: "last - first"
23.3.4.1 [lib.multiset.cons], paragraph 4: "last - first"
24.4.1 [lib.reverse.iterators], paragraph 1: "(i - 1)"
</p>

<p>
[Important note: The list is not complete, just an illustration. The
same issue might well apply to other paragraphs not listed here.]</p>

<p>None of these expressions is valid for the corresponding iterator
category.</p>

<p>Current wording in clause 25:</p>

<p>
25.1.1 [lib.alg.foreach], paragraph 1: "last - 1"
25.1.3 [lib.alg.find.end], paragraph 2: "[first1, last1 -
(last2-first2))"
25.2.8 [lib.alg.unique], paragraph 1: "(i - 1)"
25.2.8 [lib.alg.unique], paragraph 5: "(i - 1)"
</p>

<p>
However, current wording of 25 [lib.algorithms], paragraph 9 covers
neither of these four cases:</p>

<p>Current wording of 25 [lib.algorithms], paragraph 9:</p>

<p>
"In the description of the algorithms operator + and - are used for some
of the iterator categories for which they do not have to be defined. In
these cases the semantics of a+n is the same as that of</p>
<pre>{X tmp = a;
advance(tmp, n);
return tmp;
}
</pre>
<p>and that of b-a is the same as of return distance(a, b)"</p>

<p>
This paragrpah does not take the expression "iterator - n" into account,
where n denotes a value of a distance type between two iterators [Note:
According to current wording, the expression "iterator - n" would be
resolved as equivalent to "return distance(n, iterator)"]. Even if the
expression "iterator - n" were to be reinterpreted as equivalent to
"iterator + -n" [Note: This would imply that "a" and "b" were
interpreted implicitly as values of iterator types, and "n" as value of
a distance type], then 24.3.4/2 interfers because it says: "Requires: n
may be negative only for random access and bidirectional iterators.",
and none of the paragraphs quoted above requires the iterators on which
the algorithms operate to be of random access or bidirectional category.
</p>

<p>2) Description of intended behavior:</p>

<p>
For the rest of this Defect Report, it is assumed that the expression
"iterator1 + n" and "iterator1 - iterator2" has the semantics as
described in current 25 [lib.algorithms], paragraph 9, but applying to
all clauses. The expression "iterator1 - n" is equivalent to an
result-iterator for which the expression "result-iterator + n" yields an
iterator denoting the same position as iterator1 does. The terms
"iterator1", "iterator2" and "result-iterator" shall denote the value of
an iterator type, and the term "n" shall denote a value of a distance
type between two iterators.</p>

<p>
All implementations known to the author of this Defect Report comply
with these assumptions.
No impact on current code is expected.</p>

<p>3) Proposed fixes:</p>


<p>Change 25 [lib.algorithms], paragraph 9 to:</p>

<p>
"In the description of the algorithms operator + and - are used for some
of the iterator categories for which they do not have to be defined. In
this paragraph, a and b denote values of an iterator type, and n denotes
a value of a distance type between two iterators. In these cases the
semantics of a+n is the same as that of</p>
<pre>{X tmp = a;
advance(tmp, n);
return tmp;
}
</pre>
<p>,the semantics of a-n denotes the value of an iterator i for which the
following condition holds:
advance(i, n) == a,
and that of b-a is the same as of
return distance(a, b)".
</p>

<p>Comments to the new wording:</p>

<p>
a) The wording " In this paragraph, a and b denote values of an iterator
type, and n denotes a value of a distance type between two iterators."
was added so the expressions "b-a" and "a-n" are distinguished regarding
the types of the values on which they operate.
b) The wording ",the semantics of a-n denotes the value of an iterator i
for which the following condition holds: advance(i, n) == a" was added
to cover the expression 'iterator - n'. The wording "advance(i, n) == a"
was used to avoid a dependency on the semantics of a+n, as the wording
"i + n == a" would have implied. However, such a dependency might well
be deserved.
c) DR 225 is not considered in the new wording.
</p>

<p>
Proposed fixes regarding invalid iterator arithmetic expressions outside
clause 25:</p>

<p>
Either
a) Move modified 25 [lib.algorithms], paragraph 9 (as proposed above)
before any current invalid iterator arithmetic expression. In that case,
the first sentence of 25 [lib.algorithms], paragraph 9, need also to be
modified and could read: "For the rest of this International Standard,
...." / "In the description of the following clauses including this
...." / "In the description of the text below ..." etc. - anyways
substituting the wording "algorithms", which is a straight reference to
clause 25.
In that case, 25 [lib.algorithms] paragraph 9 will certainly become
obsolete.
Alternatively,
b) Add an appropiate paragraph similar to resolved 25 [lib.algorithms],
paragraph 9, to the beginning of each clause containing invalid iterator
arithmetic expressions.
Alternatively,
c) Fix each paragraph (both current wording and possible resolutions of
DRs) containing invalid iterator arithmetic expressions separately.
</p>

<p>5) References to other DRs:</p>

<p>
See DR 225.
See DR 237. The resolution could then also read "Linear in last -
first".
</p>

<p><b>Proposed resolution:</b></p>

<p><i>[Lillehammer: Minor issue, but real. We have a blanket statement
about this in 25/11. But (a) it should be in 17, not 25; and (b) it's
not quite broad enough, because there are some arithmetic expressions
it doesn't cover. Bill will provide wording.]</i></p>







<hr>
<h3><a name="498"></a>498. Requirements for partition() and stable_partition() too strong</h3>
<p><b>Section:</b> 25.2.13 [alg.partitions] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Sean Parent, Joe Gottman <b>Date:</b> 2005-05-04</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Problem:
The iterator requirements for partition() and stable_partition() [25.2.12]
are listed as BidirectionalIterator, however, there are efficient algorithms
for these functions that only require ForwardIterator that have been known
since before the standard existed. The SGI implementation includes these (see
<a href="http://www.sgi.com/tech/stl/partition.html">http://www.sgi.com/tech/stl/partition.html</a>
and
<a href="http://www.sgi.com/tech/stl/stable_partition.html">http://www.sgi.com/tech/stl/stable_partition.html</a>).
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 25.2.12 from </p>
<blockquote><pre>template&lt;class BidirectionalIterator, class Predicate&gt; 
BidirectionalIterator partition(BidirectionalIterato r first, 
                                BidirectionalIterator last, 
                                Predicate pred); 
</pre></blockquote>
<p>to </p>
<blockquote><pre>template&lt;class ForwardIterator, class Predicate&gt; 
ForwardIterator partition(ForwardIterator first, 
                          ForwardIterator last, 
                          Predicate pred); 
</pre></blockquote>
<p>Change the complexity from </p>

<blockquote><p>
At most (last - first)/2 swaps are done. Exactly (last - first) 
applications of the predicate are done. 
</p></blockquote>

<p>to </p>

<blockquote><p>
If ForwardIterator is a bidirectional_iterator, at most (last - first)/2 
swaps are done; otherwise at most (last - first) swaps are done. Exactly 
(last - first) applications of the predicate are done. 
</p></blockquote>



<p><b>Rationale:</b></p>
<p>
Partition is a "foundation" algorithm useful in many contexts (like sorting
as just one example) - my motivation for extending it to include forward
iterators is slist - without this extension you can't partition an slist
(without writing your own partition). Holes like this in the standard
library weaken the argument for generic programming (ideally I'd be able
to provide a library that would refine std::partition() to other concepts
without fear of conflicting with other libraries doing the same - but
that is a digression). I consider the fact that partition isn't defined
to work for ForwardIterator a minor embarrassment.
</p>

<p><i>[Mont Tremblant: Moved to Open, request motivation and use cases
by next meeting. Sean provided further rationale by post-meeting
mailing.]</i></p>







<hr>
<h3><a name="502"></a>502. Proposition: Clarification of the interaction between a facet and an iterator</h3>
<p><b>Section:</b> 22.1.1.1.1 [locale.category] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Christopher Conrade Zseleghovski <b>Date:</b> 2005-06-07</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.category">issues</a> in [locale.category].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Motivation:
</p>

<p>
This requirement seems obvious to me, it is the essence of code modularity. 
I have complained to Mr. Plauger that the Dinkumware library does not 
observe this principle but he objected that this behaviour is not covered in 
the standard.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Append the following point to 22.1.1.1.1:
</p>

<p>
6. The implementation of a facet of Table 52 parametrized with an 
InputIterator/OutputIterator should use that iterator only as character 
source/sink respectively.
For a *_get facet, it means that the value received depends only on the 
sequence of input characters and not on how they are accessed.
For a *_put facet, it means that the sequence of characters output depends 
only on the value to be formatted and not of how the characters are stored.
</p>

<p><i>[
Berlin:  Moved to Open, Need to clean up this area to make it clear
locales don't have to contain open ended sets of facets. Jack, Howard,
Bill.
]</i></p>







<hr>
<h3><a name="503"></a>503. more on locales</h3>
<p><b>Section:</b> 22.2 [locale.categories] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> P.J. Plauger <b>Date:</b> 2005-06-20</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.categories">active issues</a> in [locale.categories].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.categories">issues</a> in [locale.categories].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
a) In 22.2.1.1 para. 2 we refer to "the instantiations required in Table
51" to refer to the facet *objects* associated with a locale. And we
almost certainly mean just those associated with the default or "C"
locale. Otherwise, you can't switch to a locale that enforces a different
mapping between narrow and wide characters, or that defines additional
uppercase characters.
</p>

<p>
b) 22.2.1.5 para. 3 (codecvt) has the same issues.
</p>

<p>
c) 22.2.1.5.2 (do_unshift) is even worse. It *forbids* the generation of
a homing sequence for the basic character set, which might very well need
one.
</p>

<p>
d) 22.2.1.5.2 (do_length) likewise dictates that the default mapping
between wide and narrow characters be taken as one-for-one.
</p>

<p>
e) 22.2.2 para. 2 (num_get/put) is both muddled and vacuous, as far as
I can tell. The muddle is, as before, calling Table 51 a list of
instantiations. But the constraint it applies seems to me to cover
*all* defined uses of num_get/put, so why bother to say so?
</p>

<p>
f) 22.2.3.1.2 para. 1(do_decimal_point) says "The required instantiations
return '.' or L'.'.) Presumably this means "as appropriate for the
character type. But given the vague definition of "required" earlier,
this overrules *any* change of decimal point for non "C" locales.
Surely we don't want to do that.
</p>

<p>
g) 22.2.3.1.2 para. 2 (do_thousands_sep) says "The required instantiations
return ',' or L','.) As above, this probably means "as appropriate for the
character type. But this overrules the "C" locale, which requires *no*
character ('\0') for the thousands separator. Even if we agree that we
don't mean to block changes in decimal point or thousands separator,
we should also eliminate this clear incompatibility with C.
</p>

<p>
h) 22.2.3.1.2 para. 2 (do_grouping) says "The required instantiations
return the empty string, indicating no grouping." Same considerations
as for do_decimal_point.
</p>

<p>
i) 22.2.4.1 para. 1 (collate) refers to "instantiations required in Table
51". Same bad jargon.
</p>

<p>
j) 22.2.4.1.2 para. 1 (do_compare) refers to "instantiations required
in Table 51". Same bad jargon.
</p>

<p>
k) 22.2.5 para. 1 (time_get/put) uses the same muddled and vacuous
as num_get/put.
</p>

<p>
l) 22.2.6 para. 2 (money_get/put) uses the same muddled and vacuous
as num_get/put.
</p>

<p>
m) 22.2.6.3.2 (do_pos/neg_format) says "The instantiations required
in Table 51 ... return an object of type pattern initialized to
{symbol, sign, none, value}." This once again *overrides* the "C"
locale, as well as any other locale."
</p>

<p>
3) We constrain the use_facet calls that can be made by num_get/put,
so why don't we do the same for money_get/put? Or for any of the
other facets, for that matter?
</p>

<p>
4) As an almost aside, we spell out when a facet needs to use the ctype
facet, but several also need to use a codecvt facet and we don't say so.
</p>
<p><i>[
Berlin: Bill to provide wording.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="518"></a>518. Are insert and erase stable for unordered_multiset and unordered_multimap?</h3>
<p><b>Section:</b> 23.1.3 [unord.req], TR1 6.3.1 [tr.unord.req] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Matt Austern <b>Date:</b> 2005-07-03</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#unord.req">active issues</a> in [unord.req].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#unord.req">issues</a> in [unord.req].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Issue 371 deals with stability of multiset/multimap under insert and erase
(i.e. do they preserve the relative order in ranges of equal elements).
The same issue applies to unordered_multiset and unordered_multimap.
</p>
<p><i>[
Moved to open (from review):  There is no resolution.
]</i></p>


<p><i>[
Toronto:  We have a resolution now.  Moved to Review.  Some concern was noted
as to whether this conflicted with existing practice or not.  An additional
concern was in specifying (partial) ordering for an unordered container.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
Wording for the proposed resolution is taken from the equivalent text for associative containers.
</p>

<p>
Change 23.1.3 [unord.req], Unordered associative containers, paragraph 6 to:
</p>

<blockquote><p>
An unordered associative container supports <i>unique</i> keys if it may 
contain at most one element for each key. Otherwise, it supports <i>equivalent 
keys</i>. <tt>unordered_set</tt> and <tt>unordered_map</tt> support 
unique keys. <tt>unordered_multiset</tt> and <tt>unordered_multimap</tt> 
support equivalent keys. In containers that support equivalent keys, elements 
with equivalent keys are adjacent to each other. <ins>For
<tt>unordered_multiset</tt> 
and <tt>unordered_multimap</tt>,<tt> insert</tt> and <tt>erase</tt> 
preserve the relative ordering of equivalent elements.</ins>
</p></blockquote>

<p>
Change 23.1.3 [unord.req], Unordered associative containers, paragraph 8 to:
</p>

<blockquote>
<p>The elements of an unordered associative container are organized into <i>
buckets</i>. Keys with the same hash code appear in the same bucket. The number 
of buckets is automatically increased as elements are added to an unordered 
associative container, so that the average number of elements per bucket is kept 
below a bound. Rehashing invalidates iterators, changes ordering between 
elements, and changes which buckets elements appear in, but does not invalidate 
pointers or references to elements. <ins>For <tt>unordered_multiset</tt> 
and <tt>unordered_multimap</tt>, rehashing 
preserves the relative ordering of equivalent elements.</ins></p>
</blockquote>






<hr>
<h3><a name="522"></a>522. Tuple doesn't define swap</h3>
<p><b>Section:</b> 20.3 [tuple], TR1 6.1 [tr.tuple] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Andy Koenig <b>Date:</b> 2005-07-03</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Tuple doesn't define swap().  It should.
</p>
<p><i>[
Berlin: Doug to provide wording.
]</i></p>

<p><i>[
Batavia: Howard to provide wording.
]</i></p>

<p><i>[
Toronto: Howard to provide wording (really this time).
]</i></p>




<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="523"></a>523. regex case-insensitive character ranges are unimplementable as specified</h3>
<p><b>Section:</b> 28 [re] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Eric Niebler <b>Date:</b> 2005-07-01</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#re">issues</a> in [re].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
A problem with TR1 regex is currently being discussed on the Boost 
developers list. It involves the handling of case-insensitive matching 
of character ranges such as [Z-a]. The proper behavior (according to the 
ECMAScript standard) is unimplementable given the current specification 
of the TR1 regex_traits&lt;&gt; class template. John Maddock, the author of 
the TR1 regex proposal, agrees there is a problem. The full discussion 
can be found at http://lists.boost.org/boost/2005/06/28850.php (first 
message copied below). We don't have any recommendations as yet.
</p>
<p>
-- Begin original message --
</p>
<p>
The situation of interest is described in the ECMAScript specification
(ECMA-262), section 15.10.2.15:
</p>
<p>
"Even if the pattern ignores case, the case of the two ends of a range
is significant in determining which characters belong to the range.
Thus, for example, the pattern /[E-F]/i matches only the letters E, F,
e, and f, while the pattern /[E-f]/i matches all upper and lower-case
ASCII letters as well as the symbols [, \, ], ^, _, and `."
</p>
<p>
A more interesting case is what should happen when doing a
case-insentitive match on a range such as [Z-a]. It should match z, Z,
a, A and the symbols [, \, ], ^, _, and `. This is not what happens with
Boost.Regex (it throws an exception from the regex constructor).
</p>
<p>
The tough pill to swallow is that, given the specification in TR1, I
don't think there is any effective way to handle this situation.
According to the spec, case-insensitivity is handled with
regex_traits&lt;&gt;::translate_nocase(CharT) -- two characters are equivalent
if they compare equal after both are sent through the translate_nocase
function. But I don't see any way of using this translation function to
make character ranges case-insensitive. Consider the difficulty of
detecting whether "z" is in the range [Z-a]. Applying the transformation
to "z" has no effect (it is essentially std::tolower). And we're not
allowed to apply the transformation to the ends of the range, because as
ECMA-262 says, "the case of the two ends of a range is significant."
</p>
<p>
So AFAICT, TR1 regex is just broken, as is Boost.Regex. One possible fix
is to redefine translate_nocase to return a string_type containing all
the characters that should compare equal to the specified character. But
this function is hard to implement for Unicode, and it doesn't play nice
with the existing ctype facet. What a mess!
</p>
<p>
-- End original message --
</p>

<p><i>[
John Maddock adds:
]</i></p>


<p>
One small correction, I have since found that ICU's regex package does 
implement this correctly, using a similar mechanism to the current 
TR1.Regex.
</p>
<p>
Given an expression [c1-c2] that is compiled as case insensitive it:
</p>
<p>
Enumerates every character in the range c1 to c2 and converts it to it's 
case folded equivalent.  That case folded character is then used a key to a 
table of equivalence classes, and each member of the class is added to the 
list of possible matches supported by the character-class.  This second step 
isn't possible with our current traits class design, but isn't necessary if 
the input text is also converted to a case-folded equivalent on the fly.
</p>
<p>
ICU applies similar brute force mechanisms to character classes such as 
[[:lower:]] and [[:word:]], however these are at least cached, so the impact 
is less noticeable in this case.
</p>
<p>
Quick and dirty performance comparisons show that expressions such as 
"[X-\\x{fff0}]+" are indeed very slow to compile with ICU (about 200 times 
slower than a "normal" expression).  For an application that uses a lot of 
regexes this could have a noticeable performance impact.  ICU also has an 
advantage in that it knows the range of valid characters codes: code points 
outside that range are assumed not to require enumeration, as they can not 
be part of any equivalence class.  I presume that if we want the TR1.Regex 
to work with arbitrarily large character sets enumeration really does become 
impractical.
</p>
<p>
Finally note that Unicode has:
</p>
<p>
Three cases (upper, lower and title).
One to many, and many to one case transformations.
Character that have context sensitive case translations - for example an 
uppercase sigma has two different lowercase forms  - the form chosen depends 
on context(is it end of a word or not), a caseless match for an upper case 
sigma should match either of the lower case forms, which is why case folding 
is often approximated by tolower(toupper(c)).
</p>
<p>
Probably we need some way to enumerate character equivalence classes, 
including digraphs (either as a result or an input), and some way to tell 
whether the next character pair is a valid digraph in the current locale.
</p>
<p>
Hoping this doesn't make this even more complex that it was already,
</p>

<p><i>[
Portland:  Alisdair: Detect as invalid, throw an exception.
Pete: Possible general problem with case insensitive ranges.
]</i></p>




<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="527"></a>527. tr1::bind has lost its Throws clause</h3>
<p><b>Section:</b> 20.5.11.1.3 [func.bind.bind], TR1 3.6.3 [tr.func.bind.bind] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2005-10-01</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The original bind proposal gives the guarantee that tr1::bind(f, t1,
..., tN) does not throw when the copy constructors of f, t1, ..., tN
don't.
</p>

<p>
This guarantee is not present in the final version of TR1.
</p>

<p>
I'm pretty certain that we never removed it on purpose. Editorial omission? :-)
</p>

<p><i>[
Berlin: not quite editorial, needs proposed wording.
]</i></p>

<p><i>[
Batavia:  Doug to translate wording to variadic templates.
]</i></p>


<p><i>[
Toronto:  We agree but aren't quite happy with the wording.  The "t"'s no
longer refer to anything.  Alan to provide improved wording.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
In 20.5.10.1.3 [lib.func.bind.bind] ([tr.func.bind.bind]), add a new paragraph after p2:
</p>
<blockquote><p>
<i>Throws:</i> Nothing unless one of the copy constructors of <tt>f, t1, t2, ..., tN</tt>
throws an exception.
</p></blockquote>

<p>
Add a new paragraph after p4:
</p>
<blockquote><p>
<i>Throws:</i> nothing unless one of the copy constructors of <tt>f, t1, t2, ..., tN</tt>
throws an exception.
</p></blockquote>





<hr>
<h3><a name="529"></a>529. The standard encourages redundant and confusing preconditions</h3>
<p><b>Section:</b> 17.4.3.8 [res.on.required] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> David Abrahams <b>Date:</b> 2005-10-25</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
17.4.3.8/1 says:
</p>

<blockquote><p>
Violation of the preconditions specified in a function's 
Required behavior: paragraph results in undefined behavior unless the 
function's Throws: paragraph specifies throwing an exception when the 
precondition is violated.
</p></blockquote>

<p>
This implies that a precondition violation can lead to defined
behavior.  That conflicts with the only reasonable definition of
precondition: that a violation leads to undefined behavior.  Any other
definition muddies the waters when it comes to analyzing program
correctness, because precondition violations may be routinely done in
correct code (e.g. you can use std::vector::at with the full
expectation that you'll get an exception when your index is out of
range, catch the exception, and continue).  Not only is it a bad
example to set, but it encourages needless complication and redundancy
in the standard.  For example:
</p>

<blockquote><pre>  21 Strings library 
  21.3.3 basic_string capacity

  void resize(size_type n, charT c);

  5 Requires: n &lt;= max_size()
  6 Throws: length_error if n &gt; max_size().
  7 Effects: Alters the length of the string designated by *this as follows:
</pre></blockquote>

<p>
The Requires clause is entirely redundant and can be dropped.  We
could make that simplifying change (and many others like it) even
without changing 17.4.3.8/1; the wording there just seems to encourage
the redundant and error-prone Requires: clause.
</p>

<p><i>[
Batavia:  Alan and Pete to work.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
1. Change 17.4.3.8/1 to read:
</p>

<blockquote><p>
Violation of the preconditions specified in a function's
<i>Required behavior:</i> paragraph results in undefined behavior
<del>unless the function's <i>Throws:</i> paragraph specifies throwing
an exception when the precondition is violated</del>.
</p></blockquote>

<p>
2. Go through and remove redundant Requires: clauses.  Specifics to be
   provided by Dave A.
</p>

<p><i>[
Berlin: The LWG requests a detailed survey of part 2 of the proposed resolution.
]</i></p>


<p><i>[
Alan provided the survey
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2121.html">N2121</a>.
]</i></p>







<hr>
<h3><a name="539"></a>539. partial_sum and adjacent_difference should mention requirements</h3>
<p><b>Section:</b> 26.6.3 [partial.sum] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Marc Schoolderman <b>Date:</b> 2006-02-06</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
There are some problems in the definition of partial_sum and
adjacent_difference in 26.4 [lib.numeric.ops]
</p>

<p>
Unlike <tt>accumulate</tt> and <tt>inner_product</tt>, these functions are not
parametrized on a "type T", instead, 26.4.3 [lib.partial.sum] simply
specifies the effects clause as;
</p>

<blockquote><p>
Assigns to every element referred to by iterator <tt>i</tt> in the range
<tt>[result,result + (last - first))</tt> a value correspondingly equal to
</p>
<blockquote><pre>((...(* first + *( first + 1)) + ...) + *( first + ( i - result )))
</pre></blockquote>
</blockquote>

<p>
And similarly for BinaryOperation. Using just this definition, it seems
logical to expect that:
</p>


<blockquote><pre>char i_array[4] = { 100, 100, 100, 100 };
int  o_array[4];

std::partial_sum(i_array, i_array+4, o_array);
</pre></blockquote>

<p>
Is equivalent to
</p>

<blockquote><pre>int o_array[4] = { 100, 100+100, 100+100+100, 100+100+100+100 };
</pre></blockquote>

<p>
i.e. 100, 200, 300, 400, with addition happening in the <tt>result type</tt>,
<tt>int</tt>.
</p>

<p>
Yet all implementations I have tested produce 100, -56, 44, -112,
because they are using an accumulator of the <tt>InputIterator</tt>'s
<tt>value_type</tt>, which in this case is <tt>char</tt>, not <tt>int</tt>.
</p>

<p>
The issue becomes more noticeable when the result of the expression <tt>*i +
*(i+1)</tt> or <tt>binary_op(*i, *i-1)</tt> can't be converted to the
<tt>value_type</tt>. In a contrived example:
</p>

<blockquote><pre>enum not_int { x = 1, y = 2 };
...
not_int e_array[4] = { x, x, y, y };
std::partial_sum(e_array, e_array+4, o_array);
</pre></blockquote>

<p>
Is it the intent that the operations happen in the <tt>input type</tt>, or in
the <tt>result type</tt>?
</p>

<p>
If the intent is that operations happen in the <tt>result type</tt>, something
like this should be added to the "Requires" clause of 26.4.3/4
[lib.partial.sum]:
</p>

<blockquote><p>
The type of <tt>*i + *(i+1)</tt> or <tt>binary_op(*i, *(i+1))</tt> shall meet the
requirements of <tt>CopyConstructible</tt> (20.1.3) and <tt>Assignable</tt>
(23.1) types.
</p></blockquote>

<p>
(As also required for <tt>T</tt> in 26.4.1 [lib.accumulate] and 26.4.2
[lib.inner.product].)
</p>

<p>
The "auto initializer" feature proposed in
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1894.pdf">N1894</a>
is not required to
implement <tt>partial_sum</tt> this way. The 'narrowing' behaviour can still be
obtained by using the <tt>std::plus&lt;&gt;</tt> function object.
</p>

<p>
If the intent is that operations happen in the <tt>input type</tt>, then
something like this should be added instead;
</p>

<blockquote><p>
The type of *first shall meet the requirements of
<tt>CopyConstructible</tt> (20.1.3) and <tt>Assignable</tt> (23.1) types.
The result of <tt>*i + *(i+1)</tt> or <tt>binary_op(*i, *(i+1))</tt> shall be
convertible to this type.
</p></blockquote>

<p>
The 'widening' behaviour can then be obtained by writing a custom proxy
iterator, which is somewhat involved.
</p>

<p>
In both cases, the semantics should probably be clarified.
</p>

<p>
26.4.4 [lib.adjacent.difference] is similarly underspecified, although
all implementations seem to perform operations in the 'result' type:
</p>

<blockquote><pre>unsigned char i_array[4] = { 4, 3, 2, 1 };
int o_array[4];

std::adjacent_difference(i_array, i_array+4, o_array);
</pre></blockquote>

<p>
o_array is 4, -1, -1, -1 as expected, not 4, 255, 255, 255.
</p>

<p>
In any case, <tt>adjacent_difference</tt> doesn't mention the requirements on the
<tt>value_type</tt>; it can be brought in line with the rest of 26.4
[lib.numeric.ops] by adding the following to 26.4.4/2
[lib.adjacent.difference]:
</p>

<blockquote><p>
The type of <tt>*first</tt> shall meet the requirements of
<tt>CopyConstructible</tt> (20.1.3) and <tt>Assignable</tt> (23.1) types."
</p></blockquote>
<p><i>[
Berlin: Giving output iterator's value_types very controversial. Suggestion of
adding signatures to allow user to specify "accumulator".
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="546"></a>546. _Longlong and _ULonglong are integer types</h3>
<p><b>Section:</b> TR1 5.1.1 [tr.rand.req] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Matt Austern <b>Date:</b> 2006-01-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The TR sneaks in two new integer types, _Longlong and _Ulonglong, in [tr.c99].
The rest of the TR should use that type.  I believe this affects two places.
First, the random number requirements, 5.1.1/10-11, lists all of the types with
which template parameters named IntType and UIntType may be instantiated.
_Longlong (or "long long", assuming it is added to C++0x) should be added to the
IntType list, and UIntType (again, or "unsigned long long") should be added to
the UIntType list.  Second, 6.3.2 lists the types for which hash&lt;&gt; is
required to be instantiable. _Longlong and _Ulonglong should be added to that
list, so that people may use long long as a hash key.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="550"></a>550. What should the return type of pow(float,int) be?</h3>
<p><b>Section:</b> 26.7 [c.math] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2006-01-12</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#c.math">active issues</a> in [c.math].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#c.math">issues</a> in [c.math].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Assuming we adopt the
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf">C
compatibility package from C99</a>  what should be the return type of the
following signature be:
</p>
<blockquote><pre>?  pow(float, int);
</pre></blockquote>
<p>
C++03 says that the return type should be <tt>float</tt>. 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf">
TR1</a> and C90/99 say the return type should be <tt>double</tt>.  This can put
clients into a situation where C++03 provides answers that are not as high
quality as C90/C99/TR1.  For example:
</p>
<blockquote><pre>#include &lt;math.h&gt;

int main()
{
    float x = 2080703.375F;
    double y = pow(x, 2);
}
</pre></blockquote>
<p>
Assuming an IEEE 32 bit float and IEEE 64 bit double, C90/C99/TR1 all suggest:
</p>

<blockquote><pre>y = 4329326534736.390625
</pre></blockquote>

<p>
which is exactly right.  While C++98/C++03 demands:
</p>

<blockquote><pre>y = 4329326510080.
</pre></blockquote>

<p>
which is only approximately right.
</p>

<p>
I recommend that C++0X adopt the mixed mode arithmetic already adopted by
Fortran, C and TR1 and make the return type of <tt>pow(float,int)</tt> be
<tt>double</tt>.
</p>

<p><i>[
Kona (2007): Other functions that are affected by this issue include
<tt>ldexp</tt>, <tt>scalbln</tt>, and <tt>scalbn</tt>. We also believe that there is a typo in
26.7/10: <tt>float nexttoward(float, long double);</tt> [sic] should be <tt>float
nexttoward(float, float);</tt> Proposed Disposition: Review (the proposed
resolution appears above, rather than below, the heading "Proposed
resolution")
]</i></p>


<p><i>[
</i></p><p>
<i>Howard, post Kona:
</i></p>
<blockquote>
<p>
<i>Unfortunately I strongly disagree with a part of the resolution
from Kona.  I am moving from New to Open instead of to Review because I do not believe
we have consensus on the intent of the resolution.
</i></p>
<p>
<i>This issue does not include <tt>ldexp</tt>, <tt>scalbln</tt>, and <tt>scalbn</tt> because
the second integral parameter in each of these signatures (from C99) is <b>not</b> a
<i>generic parameter</i> according to C99 7.22p2.  The corresponding C++ overloads are
intended (as far as I know) to correspond directly to C99's definition of <i>generic parameter</i>.
</i></p>
<p>
<i>For similar reasons, I do not believe that the second <tt>long double</tt> parameter of
<tt>nexttoward</tt>, nor the return type of this function, is in error.  I believe the
correct signature is:
</i></p>
<blockquote>
<pre><i>float nexttoward(float, long double);
</i></pre>
</blockquote>
<p>
<i>which is what both the C++0X working paper and C99 state (as far as I currently understand).
</i></p>
<p>
<i>This is really <b>only</b> about <tt>pow(float, int)</tt>.  And this is because C++98 took one
route (with <tt>pow</tt> only) and C99 took another (with many math functions in <tt>&lt;tgmath.h&gt;</tt>.
The proposed resolution basically says: C++98 got it wrong and C99 got it right; let's go with C99.
</i></p>
</blockquote>
<i>]</i>




<p><b>Proposed resolution:</b></p>
<p>
Change 26.7 [c.math]
</p>

<blockquote><pre>float pow(float, float); 
<del>float</del> <ins>double</ins> pow(float, int);
</pre></blockquote>






<hr>
<h3><a name="556"></a>556. is Compare a BinaryPredicate?</h3>
<p><b>Section:</b> 25.3 [alg.sorting] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-02-05</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#alg.sorting">issues</a> in [alg.sorting].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In 25, p8 we allow BinaryPredicates to return a type that's convertible
to bool but need not actually be bool. That allows predicates to return
things like proxies and requires that implementations be careful about
what kinds of expressions they use the result of the predicate in (e.g.,
the expression in if (!pred(a, b)) need not be well-formed since the
negation operator may be inaccessible or return a type that's not
convertible to bool).
</p>
<p>
Here's the text for reference:
</p>
<blockquote><p>
  ...if an algorithm takes BinaryPredicate binary_pred as its argument
 and first1 and first2 as its iterator arguments, it should work
 correctly in the construct if (binary_pred(*first1, first2)){...}.
</p></blockquote>

<p>
In 25.3, p2 we require that the Compare function object return true
of false, which would seem to preclude such proxies. The relevant text
is here:
</p>
<blockquote><p>
  Compare is used as a function object which returns true if the first
  argument is less than the second, and false otherwise...
</p></blockquote>


<p><b>Proposed resolution:</b></p>
<p>
I think we could fix this by rewording 25.3, p2 to read somthing like:
</p>
<blockquote><p>
-2- <tt>Compare</tt> is <del>used as a function object which returns
<tt>true</tt> if the first argument</del> <ins>a <tt>BinaryPredicate</tt>. The
return value of the function call operator applied to an object of type
<tt>Compare</tt>, when converted to type <tt>bool</tt>, yields <tt>true</tt>
if the first argument of the call</ins> is less than the second, and
<tt>false</tt> otherwise. <tt>Compare <i>comp</i></tt> is used throughout for
algorithms assuming an ordering relation. It is assumed that <tt><i>comp</i></tt>
will not apply any non-constant function through the dereferenced iterator.
</p></blockquote>


<p><i>[
Portland:  Jack to define "convertible to bool" such that short circuiting isn't
destroyed.
]</i></p>





<hr>
<h3><a name="557"></a>557. TR1: div(_Longlong, _Longlong) vs div(intmax_t, intmax_t)</h3>
<p><b>Section:</b> 18.3 [cstdint], TR1 8.22 [tr.c99.cstdint] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Paolo Carlini <b>Date:</b> 2006-02-06</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#cstdint">issues</a> in [cstdint].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I'm seeing a problem with such overloads: when, _Longlong == intmax_t ==
long long we end up, essentially, with the same arguments and different
return types (lldiv_t and imaxdiv_t, respectively). Similar issue with
abs(_Longlong) and abs(intmax_t), of course.
</p>
<p>
Comparing sections 8.25 and 8.11, I see an important difference,
however: 8.25.3 and 8.25.4 carefully describe div and abs for _Longlong
types (rightfully, because not moved over directly from C99), whereas
there is no equivalent in 8.11: the abs and div overloads for intmax_t
types appear only in the synopsis and are not described anywhere, in
particular no mention in 8.11.2 (at variance with 8.25.2).
</p>
<p>
I'm wondering whether we really, really, want div and abs for intmax_t...
</p>



<p><b>Proposed resolution:</b></p>



<p><i>[
Portland: no consensus.
]</i></p>


<p><b>Rationale:</b></p>
<p><i>[
Batavia, Bill: The <tt>&lt;cstdint&gt;</tt> synopsis in TR1 8.11.1 [tr.c99.cinttypes.syn] contains:
]</i></p>

<blockquote><pre>intmax_t imaxabs(intmax_t i);
intmax_t abs(intmax_t i);

imaxdiv_t imaxdiv(intmax_t numer, intmax_t denom);
imaxdiv_t div(intmax_t numer, intmax_t denom);
</pre></blockquote>

<p><i>[
and in TR1 8.11.2 [tr.c99.cinttypes.def]:
]</i></p>


<blockquote><p>
The header defines all functions, types, and macros the same as C99
subclause 7.8.
</p></blockquote>

<p><i>[
This is as much definition as we give for most other C99 functions,
so nothing need change. We might, however, choose to add the footnote:
]</i></p>


<blockquote><p>
[<i>Note:</i> These overloads for <tt>abs</tt> and <tt>div</tt> may well be equivalent to
those that take <tt>long long</tt> arguments. If so, the implementation is
responsible for avoiding conflicting declarations. -- <i>end note</i>]
</p></blockquote>






<hr>
<h3><a name="561"></a>561. inserter overly generic</h3>
<p><b>Section:</b> 24.4.2.6.5 [inserter] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2006-02-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The declaration of <tt>std::inserter</tt> is:
</p>

<blockquote><pre>template &lt;class Container, class Iterator&gt;
insert_iterator&lt;Container&gt;
inserter(Container&amp; x, Iterator i);
</pre></blockquote>

<p>
The template parameter <tt>Iterator</tt> in this function is completely unrelated
to the template parameter <tt>Container</tt> when it doesn't need to be.  This
causes the code to be overly generic.  That is, any type at all can be deduced
as <tt>Iterator</tt>, whether or not it makes sense.  Now the same is true of
<tt>Container</tt>.  However, for every free (unconstrained) template parameter
one has in a signature, the opportunity for a mistaken binding grows geometrically.
</p>

<p>
It would be much better if <tt>inserter</tt> had the following signature instead:
</p>

<blockquote><pre>template &lt;class Container&gt;
insert_iterator&lt;Container&gt;
inserter(Container&amp; x, typename Container::iterator i);
</pre></blockquote>

<p>
Now there is only one free template parameter.  And the second argument to
<tt>inserter</tt> must be implicitly convertible to the container's iterator,
else the call will not be a viable overload (allowing other functions in the
overload set to take precedence).  Furthermore, the first parameter must have a
nested type named <tt>iterator</tt>, or again the binding to <tt>std::inserter</tt>
is not viable.  Contrast this with the current situation
where any type can bind to <tt>Container</tt> or <tt>Iterator</tt> and those
types need not be anything closely related to containers or iterators.
</p>

<p>
This can adversely impact well written code.  Consider:
</p>

<blockquote><pre>#include &lt;iterator&gt;
#include &lt;string&gt;

namespace my
{

template &lt;class String&gt;
struct my_type {};

struct my_container
{
template &lt;class String&gt;
void push_back(const my_type&lt;String&gt;&amp;);
};

template &lt;class String&gt;
void inserter(const my_type&lt;String&gt;&amp; m, my_container&amp; c) {c.push_back(m);}

}  // my

int main()
{
    my::my_container c;
    my::my_type&lt;std::string&gt; m;
    inserter(m, c);
}
</pre></blockquote>

<p>
Today this code fails because the call to <tt>inserter</tt> binds to
<tt>std::inserter</tt> instead of to <tt>my::inserter</tt>.  However with the
proposed change <tt>std::inserter</tt> will no longer be a viable function which
leaves only <tt>my::inserter</tt> in the overload resolution set.  Everything
works as the client intends.
</p>

<p>
To make matters a little more insidious, the above example works today if you
simply change the first argument to an rvalue:
</p>

<blockquote><pre>    inserter(my::my_type(), c);
</pre></blockquote>

<p>
It will also work if instantiated with some string type other than
<tt>std::string</tt> (or any other <tt>std</tt> type).  It will also work if
<tt>&lt;iterator&gt;</tt> happens to not get included.
</p>

<p>
And it will fail again for such inocuous reaons as <tt>my_type</tt> or
<tt>my_container</tt> privately deriving from any <tt>std</tt> type.
</p>

<p>
It seems unfortunate that such simple changes in the client's code can result
in such radically differing behavior.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change 24.2:
</p>

<blockquote><p>
<b>24.2 Header</b> <tt>&lt;iterator&gt;</tt> <b>synopsis</b>
</p>
<blockquote><pre>...
template &lt;class Container<del>, class Iterator</del>&gt;
   insert_iterator&lt;Container&gt; inserter(Container&amp; x, <del>Iterator</del> <ins>typename Container::iterator</ins> i);
...
</pre></blockquote>
</blockquote>

<p>
Change 24.4.2.5:
</p>

<blockquote><p>
<b>24.4.2.5 Class template</b> <tt>insert_iterator</tt></p>
<blockquote><pre>...
template &lt;class Container<del>, class Iterator</del>&gt;
   insert_iterator&lt;Container&gt; inserter(Container&amp; x, <del>Iterator</del> <ins>typename Container::iterator</ins> i);
...
</pre></blockquote>
</blockquote>

<p>
Change 24.4.2.6.5:
</p>

<blockquote>
<p>
<b>24.4.2.6.5</b> <tt>inserter</tt>
</p>
<pre>template &lt;class Container<del>, class Inserter</del>&gt;
   insert_iterator&lt;Container&gt; inserter(Container&amp; x, <del>Inserter</del> <ins>typename Container::iterator</ins> i);
</pre>
<blockquote><p>
-1- <i>Returns:</i> <tt>insert_iterator&lt;Container&gt;(x,<del>typename Container::iterator(</del>i<del>)</del>)</tt>.
</p></blockquote>
</blockquote>



<p><i>[
Kona (2007): This issue will probably be addressed as a part of the
concepts overhaul of the library anyway, but the proposed resolution is
correct in the absence of concepts. Proposed Disposition: Ready
]</i></p>





<hr>
<h3><a name="562"></a>562. stringbuf ctor inefficient</h3>
<p><b>Section:</b> 27.7 [string.streams] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-02-23</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#string.streams">issues</a> in [string.streams].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

For  better efficiency,  the requirement  on the  stringbuf  ctor that
takes  a  string  argument  should  be  loosened  up  to  let  it  set
<code>epptr()</code>  beyond  just   one  past  the  last  initialized
character  just like  <code>overflow()</code> has  been changed  to be
allowed  to  do   (see  issue  432).  That  way   the  first  call  to
<code>sputc()</code> on  an object won't  necessarily cause a  call to
<code>overflow</code>. The corresponding change  should be made to the
string overload of the <code>str()</code> member function.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

Change 27.7.1.1, p3 of the Working Draft, N1804, as follows:

        </p>

<blockquote><pre>explicit basic_stringbuf(const basic_string&lt;charT,traits,Allocator&gt;&amp; <i>s<del>tr</del></i>,
               ios_base::openmode <i>which</i> = ios_base::in | ios_base::out);
</pre>

<p>
-3- <i>Effects:</i>  Constructs an object of class <tt>basic_stringbuf</tt>,
initializing the base class with <tt>basic_streambuf()</tt>
(27.5.2.1), and initializing <tt><i>mode</i></tt> with <tt><i>which</i></tt>.
Then <ins>calls <tt>str(<i>s</i>)</tt>.</ins> <del>copies the content of
<i>str</i> into the <tt>basic_stringbuf</tt> underlying character
sequence. If <tt><i>which</i> &amp; ios_base::out</tt> is true, initializes the
output sequence such that <tt>pbase()</tt> points to the first underlying
character, <tt>epptr()</tt> points one past the last underlying character, and
<tt>pptr()</tt> is equal to <tt>epptr()</tt> if <tt><i>which</i> &amp; ios_base::ate</tt>
is true, otherwise <tt>pptr()</tt> is equal to <tt>pbase()</tt>. If
<tt>which &amp; ios_base::in</tt> is true, initializes the input sequence such
that <tt>eback()</tt> and <tt>gptr()</tt> point to the first underlying 
character and <tt>egptr()</tt> points one past the last underlying character.</del>
</p>
</blockquote>

        <p>

Change the Effects clause of the <code>str()</code> in 27.7.1.2, p2 to
read:

        </p>
<blockquote>
<p>
-2- <i>Effects:</i> Copies the content<ins>s</ins> of <tt><i>s</i></tt> into the
<tt>basic_stringbuf</tt> underlying character sequence <ins>and
initializes the input and output sequences according to <tt><i>mode</i></tt></ins>.
<del>If
<tt><i>mode</i> &amp; ios_base::out</tt> is true, initializes the output
sequence such that <tt>pbase()</tt> points to the first underlying character, 
<tt>epptr()</tt> points one past the last underlying character, and <tt>pptr()</tt>
is equal to <tt>epptr()</tt> if <tt><i>mode</i> &amp; ios_base::in</tt>
is true, otherwise <tt>pptr()</tt> is equal to <tt>pbase()</tt>. If
<tt>mode &amp; ios_base::in</tt> is true, initializes the input sequence 
such that <tt>eback()</tt> and <tt>gptr()</tt> point to the first underlying
character and <tt>egptr()</tt> points one past the last underlying character.</del>
</p>

        <p>

<ins>-3- <i>Postconditions:</i>  If  <code>mode  &amp; ios_base::out</code>  is  true,
<code>pbase()</code>  points  to the  first  underlying character  and
<code>(epptr() &gt;= pbase() + s.size())</code> holds; in addition, if
<code>mode &amp; ios_base::in</code> is true, <code>(pptr() == pbase()
+ s.data())</code>  holds, otherwise <code>(pptr()  == pbase())</code>
is   true.    If  <code>mode   &amp;   ios_base::in</code>  is   true,
<code>eback()</code>  points to  the first  underlying  character, and
<code>(gptr()  ==  eback())</code>  and  <code>(egptr() ==  eback()  +
s.size())</code> hold.</ins>

        </p>
</blockquote>


<p><i>[
Kona (2007) Moved to Ready.
]</i></p>





<hr>
<h3><a name="563"></a>563. stringbuf seeking from end</h3>
<p><b>Section:</b> 27.7.1.4 [stringbuf.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-02-23</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#stringbuf.virtuals">active issues</a> in [stringbuf.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#stringbuf.virtuals">issues</a> in [stringbuf.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
According to  Table 92  (unchanged by issue  432), when  <code>(way ==
end)</code> the  <code>newoff</code> value in out mode  is computed as
the difference between <code>epptr()</code> and <code>pbase()</code>.
</p>
        <p>

This value  isn't meaningful unless the  value of <code>epptr()</code>
can be  precisely controlled by a  program.  That used  to be possible
until  we accepted the  resolution of  issue 432,  but since  then the
requirements on <code>overflow()</code> have  been relaxed to allow it
to  make  more than  1  write  position  available (i.e.,  by  setting
<code>epptr()</code>     to     some     unspecified    value     past
<code>pptr()</code>).      So    after     the    first     call    to
<code>overflow()</code>  positioning the  output sequence  relative to
end will have unspecified results.

        </p>
        <p>

In  addition,  in <code>in|out</code>  mode,  since <code>(egptr()  ==
epptr())</code> need not hold, there are two different possible values
for   <code>newoff</code>:    <code>epptr()   -   pbase()</code>   and
<code>egptr() - eback()</code>.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

Change the <code>newoff</code>  column in the last row  of Table 94 to
read:

        </p>
<blockquote><p>

the <del>end</del> <ins>high mark</ins> pointer minus the beginning 
pointer (<code><del>xend</del> <ins>high_mark</ins> - xbeg</code>).

</p></blockquote>


<p><i>[
Kona (2007) Moved to Ready.
]</i></p>





<hr>
<h3><a name="564"></a>564. stringbuf seekpos underspecified</h3>
<p><b>Section:</b> 27.7.1.4 [stringbuf.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-02-23</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#stringbuf.virtuals">active issues</a> in [stringbuf.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#stringbuf.virtuals">issues</a> in [stringbuf.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The   effects  of  the   <code>seekpos()</code>  member   function  of
<code>basic_stringbuf</code>  simply say  that the  function positions
the  input and/or  output  sequences  but fail  to  spell out  exactly
how. This is in contrast  to the detail in which <code>seekoff()</code>
is described.
</p>


<p><b>Proposed resolution:</b></p>
        <p>

Change 27.7.1.3, p13 to read:

        </p>
<blockquote>
<p>
-13- <i>Effects:</i> <ins>Same as <tt>seekoff(off_type(<i>sp</i>), ios_base::beg,
<i>which</i>)</tt>.</ins> <del>Alters the stream position within the controlled sequences,
if possible, to correspond to the stream position stored in <tt><i>sp</i></tt>
(as described below).</del>
</p>
<ul>
<li><del>If <tt>(<i>which</i> &amp; ios_base::in) != 0</tt>, positions the input sequence.</del></li>
<li><del>If <tt>(<i>which</i> &amp; ios_base::out) != 0</tt>, positions the output sequence.</del></li>
<li><del>If <tt><i>sp</i></tt> is an invalid stream position, or if the function
positions neither sequence, the positioning operation fails. If <tt><i>sp</i></tt>
has not been obtained by a previous successful call to one of the positioning
functions (<tt>seekoff</tt>, <tt>seekpos</tt>, <tt>tellg</tt>, <tt>tellp</tt>)
the effect is undefined.</del></li>
</ul>
</blockquote>


<p><i>[
Kona (2007): A <tt>pos_type</tt> is a position in a stream by
definition, so there is no ambiguity as to what it means. Proposed
Disposition: NAD
]</i></p>


<p><i>[
Post-Kona Martin adds:
I'm afraid I disagree
with the Kona '07 rationale for marking it NAD. The only text
that describes precisely what it means to position the input
or output sequence is in <tt>seekoff()</tt>. The <tt>seekpos()</tt> Effects
clause is inadequate in comparison and the proposed resolution
plugs the hole by specifying <tt>seekpos()</tt> in terms of <tt>seekoff()</tt>.
]</i></p>





<hr>
<h3><a name="565"></a>565. xsputn inefficient</h3>
<p><b>Section:</b> 27.5.2.4.5 [streambuf.virt.put] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-02-23</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

<tt>streambuf::xsputn()</tt>  is  specified  to  have  the  effect  of
"writing up to  <tt>n</tt> characters to the output  sequence as if by
repeated calls to <tt>sputc(c)</tt>."

        </p>
        <p>

Since  <tt>sputc()</tt> is required  to call  <tt>overflow()</tt> when
<tt>(pptr()    ==   epptr())</tt>    is   true,    strictly   speaking
<tt>xsputn()</tt>  should do  the same.   However, doing  so  would be
suboptimal in  some interesting cases,  such as in unbuffered  mode or
when the buffer is <tt>basic_stringbuf</tt>.

        </p>
        <p>

Assuming  calling <tt>overflow()</tt>  is  not really  intended to  be
required  and the  wording is  simply  meant to  describe the  general
effect of appending to the end  of the sequence it would be worthwhile
to  mention in  <tt>xsputn()</tt> that  the function  is  not actually
required to cause a call to <tt>overflow()</tt>.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

Add the following sentence  to the <tt>xsputn()</tt> Effects clause in
27.5.2.4.5, p1 (N1804):

        </p>
        <blockquote>    
            <p>
-1- <i>Effects:</i> Writes up to <tt><i>n</i></tt> characters to the output
sequence as if by repeated calls to <tt>sputc(<i>c</i>)</tt>. The characters 
written are obtained from successive elements of the array whose first element
is designated by <tt><i>s</i></tt>. Writing stops when either <tt><i>n</i></tt>
characters have been written or a call to <tt>sputc(<i>c</i>)</tt> would return
<tt>traits::eof()</tt>. <ins>It is  uspecified whether the function  calls
<tt>overflow()</tt> when <tt>(pptr() ==  epptr())</tt> becomes true or whether
it achieves the same effects by other means.</ins>
            </p>
        </blockquote>    
        <p>

In addition,  I suggest to  add a footnote  to this function  with the
same text as Footnote 292 to  make it extra clear that derived classes
are permitted to override <tt>xsputn()</tt> for efficiency.

        </p>


<p><i>[
Kona (2007): We want to permit a <tt>streambuf</tt> that streams output directly
to a device without making calls to <tt>sputc</tt> or <tt>overflow</tt>. We believe that
has always been the intention of the committee. We believe that the
proposed wording doesn't accomplish that. Proposed Disposition: Open
]</i></p>





<hr>
<h3><a name="567"></a>567. streambuf inserter and extractor should be unformatted</h3>
<p><b>Section:</b> 27.6 [iostream.format] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-02-25</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#iostream.format">active issues</a> in [iostream.format].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#iostream.format">issues</a> in [iostream.format].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

Issue  60 explicitly made  the extractor  and inserter  operators that
take a  <tt>basic_streambuf*</tt> argument formatted  input and output
functions,  respectively.  I  believe that's  wrong, certainly  in the
case of  the extractor, since formatted functions  begin by extracting
and  discarding  whitespace.  The  extractor  should  not discard  any
characters.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

I propose to  change each operator to behave  as unformatted input and
output function,  respectively. The changes below are  relative to the
working draft document number N1804.

        </p>
        <p>

Specifically, change 27.6.1.2.3, p14 as follows:

        </p>

            <blockquote>
        <p>

<i>Effects</i>:  Behaves as  a<ins>n un</ins>formatted  input function
(as   described   in   <del>27.6.1.2.1</del><ins>27.6.1.3,   paragraph
1</ins>).

        </p>
            </blockquote>
        <p>

And change 27.6.2.5.3, p7 as follows:

        </p>

            <blockquote>
        <p>

<i>Effects</i>: Behaves  as a<ins>n un</ins>formatted  output function
(as   described   in   <del>27.6.2.5.1</del><ins>27.6.2.6,   paragraph
1</ins>).

        </p>
            </blockquote>


<p><i>[
Kona (2007): Proposed Disposition: Ready
]</i></p>





<hr>
<h3><a name="568"></a>568. log2 overloads missing</h3>
<p><b>Section:</b> TR1 8.16.4 [tr.c99.cmath.over] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Paolo Carlini <b>Date:</b> 2006-03-07</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<tt>log2</tt> is missing from the list of "additional overloads" in TR1 8.16.4 [tr.c99.cmath.over] p1.
</p>

<p>
Hinnant:  This is a TR1 issue only.  It is fixed in the current (N2135) WD.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add <tt>log2</tt> to the list of functions in TR1 8.16.4 [tr.c99.cmath.over] p1.
</p>





<hr>
<h3><a name="570"></a>570. Request adding additional explicit specializations of char_traits</h3>
<p><b>Section:</b> 21.1 [char.traits] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Jack Reeves <b>Date:</b> 2006-04-06</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Currently, the Standard Library specifies only a declaration for template class
char_traits&lt;&gt; and requires the implementation provide two explicit
specializations: char_traits&lt;char&gt; and char_traits&lt;wchar_t&gt;. I feel the Standard
should require explicit specializations for all built-in character types, i.e.
char, wchar_t, unsigned char, and signed char.
</p>
<p>
I have put together a paper
(<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1985.htm">N1985</a>)
that describes this in more detail and
includes all the necessary wording.
</p>
<p><i>[
Portland: Jack will rewrite
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1985.htm">N1985</a>
to propose a primary template that will work with other integral types.
]</i></p>

<p><i>[
Toronto: issue has grown with addition of <tt>char16_t</tt> and <tt>char32_t</tt>.
]</i></p>



<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="573"></a>573. C++0x file positioning should handle modern file sizes</h3>
<p><b>Section:</b> 27.4.3 [fpos] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Beman Dawes <b>Date:</b> 2006-04-12</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#fpos">issues</a> in [fpos].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
There are two deficiencies related to file sizes:
</p>
<ol>
<li>It doesn't appear that the Standard Library is specified in
      a way that handles modern file sizes, which are often too
      large to be represented by an unsigned long.</li>

<li>The std::fpos class does not currently have the ability to
      set/get file positions.</li>
</ol>
<p>
The Dinkumware implementation of the Standard Library as shipped with the Microsoft compiler copes with these issues by:
</p>
<ol type="A">
<li>Defining fpos_t be long long, which is large enough to
      represent any file position likely in the foreseeable future.</li>

<li>Adding member functions to class fpos. For example,
<blockquote><pre>fpos_t seekpos() const;
</pre></blockquote>
</li>
</ol>
<p>
Because there are so many types relating to file positions and offsets (fpos_t,
fpos, pos_type, off_type, streamoff, streamsize, streampos, wstreampos, and
perhaps more), it is difficult to know if the Dinkumware extensions are
sufficient. But they seem a useful starting place for discussions, and they do
represent existing practice.
</p>

<p><i>[
Kona (2007): We need a paper. It would be nice if someone proposed
clarifications to the definitions of <tt>pos_type</tt> and <tt>off_type</tt>. Currently
these definitions are horrible. Proposed Disposition: Open
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="574"></a>574. DR 369 Contradicts Text</h3>
<p><b>Section:</b> 27.3 [iostream.objects] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Pete Becker <b>Date:</b> 2006-04-18</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#iostream.objects">issues</a> in [iostream.objects].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
lib.iostream.objects requires that the standard stream objects are never
destroyed, and it requires that they be destroyed.
</p>
<p>
DR 369 adds words to say that we really mean for ios_base::Init objects to force
construction of standard stream objects. It ends, though, with the phrase "these
stream objects shall be destroyed after the destruction of dynamically ...".
However, the rule for destruction is stated in the standard: "The objects are
not destroyed during program execution."
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 27.3 [iostream.objects]/1:
</p>

<blockquote>
<p>
-2- The objects are constructed and the associations are established at
some time prior to or during the first time an object of class
<tt>ios_base::Init</tt> is constructed, and in any case before the body of main
begins execution.<sup>290)</sup> The objects are not destroyed during program
execution.<sup>291)</sup> If a translation unit includes <tt>&lt;iostream&amp;t;</tt> or explicitly
constructs an <tt>ios_base::Init</tt> object, these stream objects shall be
constructed before dynamic initialization of non-local objects defined
later in that translation unit<del>, and these stream objects shall be
destroyed after the destruction of dynamically initialized non-local
objects defined later in that translation unit</del>.
</p>
</blockquote>


<p><i>[
Kona (2007): From 27.3 [iostream.objects]/2, strike the words "...and these stream objects
shall be destroyed after the destruction of dynamically initialized
non-local objects defined later in that translation unit." Proposed
Disposition: Review
]</i></p>





<hr>
<h3><a name="579"></a>579. erase(iterator) for unordered containers should not return an iterator</h3>
<p><b>Section:</b> 23.1.3 [unord.req] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Joaquín M López Muñoz <b>Date:</b> 2006-06-13</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#unord.req">active issues</a> in [unord.req].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#unord.req">issues</a> in [unord.req].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
See
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2023.pdf">N2023</a>
for full discussion.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Option 1:
</p>

<p>
The problem can be eliminated by omitting the requirement that <tt>a.erase(q)</tt> return an 
iterator. This is, however, in contrast with the equivalent requirements for other 
standard containers.
</p>

<p>
Option 2:
</p>

<p>
<tt>a.erase(q)</tt> can be made to compute the next iterator only when explicitly requested: 
the technique consists in returning a proxy object implicitly convertible to <tt>iterator</tt>, so 
that
</p>

<blockquote><pre>iterator q1=a.erase(q);
</pre></blockquote>

<p>
works as expected, while
</p>

<blockquote><pre>a.erase(q);
</pre></blockquote>

<p>
does not ever invoke the conversion-to-iterator operator, thus avoiding the associated 
computation. To allow this technique, some sections of TR1 along the line "return value 
is an iterator..." should be changed to "return value is an unspecified object implicitly 
convertible to an iterator..." Although this trick is expected to work transparently, it can 
have some collateral effects when the expression <tt>a.erase(q)</tt> is used inside generic 
code.
</p>



<p><b>Rationale:</b></p>
<p>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2023.pdf">N2023</a>
was discussed in Portland and the consensus was that there appears to be
no need for either change proposed in the paper.  The consensus opinion
was that since the iterator could serve as its own proxy, there appears
to be no need for the change. In general, "converts to" is undesirable
because it interferes with template matching.
</p>

<p>
Post Toronto:  There does not at this time appear to be consensus with the Portland consensus. 
</p>





<hr>
<h3><a name="580"></a>580. unused allocator members</h3>
<p><b>Section:</b> 20.1.2 [allocator.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-06-14</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#allocator.requirements">active issues</a> in [allocator.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#allocator.requirements">issues</a> in [allocator.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Duplicate of:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#479">479</a></p>
<p><b>Discussion:</b></p>
        <p>

C++ Standard Library  templates that take an allocator  as an argument
are    required    to    call    the    <code>allocate()</code>    and
<code>deallocate()</code>  members of the  allocator object  to obtain
storage.  However, they do not appear to be required to call any other
allocator      members      such     as      <code>construct()</code>,
<code>destroy()</code>,           <code>address()</code>,          and
<code>max_size()</code>.  This makes these allocator members less than
useful in portable programs.

        </p>
        <p>

It's unclear to me whether the absence of the requirement to use these
allocator  members  is  an  unintentional  omission  or  a  deliberate
choice. However,  since the functions exist in  the standard allocator
and  since  they are  required  to  be  provided by  any  user-defined
allocator I  believe the standard  ought to be clarified  to explictly
specify  whether programs  should or  should not  be able  to  rely on
standard containers calling the functions.

        </p>
        <p>

I  propose  that all  containers  be required  to  make  use of  these
functions.

        </p>
<p><i>[
Batavia:  We support this resolution.  Martin to provide wording.
]</i></p>

<p><i>[
pre-Oxford:  Martin provided wording.
]</i></p>

    

    <p><b>Proposed resolution:</b></p>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<p>

Specifically, I propose to change 23.1 [container.requirements],
p9 as follows:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<blockquote>
<p>
-9- Copy constructors &nbsp;for all container types defined &nbsp;in this clause
<ins>that &nbsp;&nbsp;are &nbsp;parametrized &nbsp;on &nbsp;&nbsp;<code>Allocator</code></ins> &nbsp;copy
<del>an</del><ins>the</ins> &nbsp;allocator argument from &nbsp;their respective
first parameters.

All other &nbsp;constructors for &nbsp;these container types &nbsp;take a<del>n</del>
<ins>const</ins> &nbsp;<code>Allocator&amp;</code> &nbsp;argument &nbsp;(20.1.6), &nbsp;an
allocator whose <code>value_type</code> is the same as the container's
<code>value_type</code>.

A copy of this &nbsp;argument <del>is</del><ins>shall be</ins> used for any
memory &nbsp;allocation <ins> and &nbsp;deallocation</ins> performed<del>,</del>
by these &nbsp;constructors and by all &nbsp;member functions<del>,</del> during
the &nbsp;lifetime &nbsp;of each &nbsp;container &nbsp;object. &nbsp;&nbsp;<ins>Allocation shall &nbsp;be
performed &nbsp;"as &nbsp;if" &nbsp;by &nbsp;calling &nbsp;the &nbsp;<code>allocate()</code> &nbsp;member
function on &nbsp;a copy &nbsp;of the allocator &nbsp;object of the &nbsp;appropriate type
<sup>New &nbsp;Footnote)</sup>, &nbsp;&nbsp;and &nbsp;deallocation &nbsp;"as &nbsp;&nbsp;if" &nbsp;by &nbsp;calling
<code>deallocate()</code> on &nbsp;a copy of &nbsp;the same allocator &nbsp;object of
the corresponding type.</ins>

<ins>A &nbsp;copy of &nbsp;this argument &nbsp;shall also &nbsp;be used &nbsp;to &nbsp;construct and
destroy objects whose lifetime &nbsp;is managed by the container, including
but not &nbsp;limited to those of &nbsp;the container's <code>value_type</code>,
and &nbsp;to &nbsp;obtain &nbsp;their &nbsp;address. &nbsp;&nbsp;All &nbsp;objects &nbsp;residing &nbsp;in &nbsp;storage
allocated by a &nbsp;container's allocator shall be constructed &nbsp;"as if" by
calling the <code>construct()</code> member &nbsp;function on a copy of the
allocator object of &nbsp;the appropriate type. &nbsp;The same &nbsp;objects shall be
destroyed "as if" &nbsp;by calling <code>destroy()</code> on a &nbsp;copy of the
same allocator object &nbsp;of the same type. &nbsp;The &nbsp;address of such objects
shall be obtained "as if" by calling the <code>address()</code> member
function &nbsp;on &nbsp;a &nbsp;copy &nbsp;of &nbsp;the allocator &nbsp;object &nbsp;of &nbsp;the &nbsp;appropriate
type.</ins>

<ins>Finally, a copy &nbsp;of this argument shall be &nbsp;used by its container
object to determine &nbsp;the maximum number of objects &nbsp;of the container's
<code>value_type</code> the container may &nbsp;store at the same time. The
container &nbsp;member function <code>max_size()</code>
obtains &nbsp;this number
from &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;value
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;returned &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;by
&nbsp;&nbsp;&nbsp;&nbsp;a &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;call
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;to
<code>get_allocator().max_size()</code>.</ins>

In &nbsp;&nbsp;all &nbsp;container &nbsp;&nbsp;types &nbsp;defined &nbsp;&nbsp;in &nbsp;this &nbsp;&nbsp;clause <ins>that &nbsp;are
parametrized &nbsp;&nbsp;&nbsp;&nbsp;on &nbsp;&nbsp;&nbsp;<code>Allocator</code></ins>, &nbsp;&nbsp;&nbsp;&nbsp;the &nbsp;&nbsp;&nbsp;member
<code>get_allocator()</code> &nbsp;&nbsp;&nbsp;&nbsp;returns
&nbsp;&nbsp;&nbsp;&nbsp;a &nbsp;&nbsp;&nbsp;&nbsp;copy
&nbsp;&nbsp;&nbsp;&nbsp;of &nbsp;&nbsp;&nbsp;&nbsp;the
<code>Allocator</code> &nbsp;&nbsp;&nbsp;&nbsp;object
&nbsp;&nbsp;&nbsp;&nbsp;used &nbsp;&nbsp;&nbsp;&nbsp;to
&nbsp;&nbsp;&nbsp;construct &nbsp;&nbsp;&nbsp;&nbsp;the
container.<sup>258)</sup>
</p>
<p>
New Footnote: This type &nbsp;may be different from <code>Allocator</code>:
it &nbsp;&nbsp;&nbsp;&nbsp;may &nbsp;&nbsp;&nbsp;be
&nbsp;&nbsp;&nbsp;&nbsp;derived &nbsp;&nbsp;&nbsp;from
&nbsp;&nbsp;&nbsp;&nbsp;<code>Allocator</code> &nbsp;&nbsp;&nbsp;via
<code>Allocator::rebind&lt;U&gt;::other</code> &nbsp;&nbsp;for &nbsp;the &nbsp;appropriate
type <code>U</code>.
</p>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</blockquote>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<p>
The proposed wording seems cumbersome but I couldn't think of a better
way &nbsp;&nbsp;to &nbsp;describe &nbsp;&nbsp;the
&nbsp;&nbsp;requirement &nbsp;that &nbsp;&nbsp;containers &nbsp;use
&nbsp;&nbsp;their
<code>Allocator</code> &nbsp;to manage &nbsp;only objects &nbsp;(regardless &nbsp;of their
type) &nbsp;that &nbsp;persist &nbsp;over &nbsp;their &nbsp;lifetimes &nbsp;and &nbsp;not, &nbsp;for &nbsp;example,
temporaries &nbsp;created on the &nbsp;stack. That &nbsp;is, containers &nbsp;shouldn't be
required &nbsp;to &nbsp;call &nbsp;<code>Allocator::construct(Allocator::allocate(1),
elem)</code> &nbsp;just to &nbsp;construct a &nbsp;temporary copy &nbsp;of an &nbsp;element, or
<code>Allocator::destroy(Allocator::address(temp), &nbsp;&nbsp;&nbsp;&nbsp;1)</code> &nbsp;&nbsp;&nbsp;to
destroy temporaries.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p>


<p><i>[
Howard: This same paragraph will need some work to accommodate <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#431">431</a>.
]</i></p>


<p><i>[
post Oxford:  This would be rendered NAD Editorial by acceptance of
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2257.html">N2257</a>.
]</i></p>





<hr>
<h3><a name="581"></a>581. <code>flush()</code> not unformatted function</h3>
<p><b>Section:</b> 27.6.2.7 [ostream.unformatted] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-06-14</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#ostream.unformatted">issues</a> in [ostream.unformatted].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

The resolution of issue 60 changed <code>basic_ostream::flush()</code>
so as not  to require it to behave as  an unformatted output function.
That has at least two in my opinion problematic consequences:

        </p>
        <p>

First, <code>flush()</code>  now calls <code>rdbuf()-&gt;pubsync()</code>
unconditionally, without  regard to the  state of the stream.  I can't
think of any reason why <code>flush()</code> should behave differently
from the vast majority of stream functions in this respect.

        </p>
        <p>

Second, <code>flush()</code> is not  required to catch exceptions from
<code>pubsync()</code> or set  <code>badbit</code> in response to such
events. That doesn't seem right either, as most other stream functions
do so.

        </p>
    

    <p><b>Proposed resolution:</b></p>
        <p>

I  propose  to revert  the  resolution of  issue  60  with respect  to
<code>flush()</code>. Specifically,  I propose to  change 27.6.2.6, p7
as follows:

        </p>

<p>
Effects: <ins>Behaves as an  unformatted output function (as described
in 27.6.2.6, paragraph 1). </ins>If <code>rdbuf()</code> is not a null
pointer,  <ins>constructs a  sentry  object.  If  this object  returns
<code>true</code> when converted to a  value of type bool the function
</ins>calls <code>rdbuf()-&gt;pubsync()</code>.  If that function returns
-1    calls    <code>setstate(badbit)</code>    (which    may    throw
<code>ios_base::failure</code>  (27.4.4.3)).   <ins>Otherwise, if  the
sentry object returns <code>false</code>, does nothing.</ins><del>Does
not  behave  as  an  unformatted  output  function  (as  described  in
27.6.2.6, paragraph 1).</del>
</p>

    

<p><i>[
Kona (2007): Proposed Disposition: Ready
]</i></p>





<hr>
<h3><a name="582"></a>582. specialized algorithms and volatile storage</h3>
<p><b>Section:</b> 20.6.4.1 [uninitialized.copy] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-06-14</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#uninitialized.copy">active issues</a> in [uninitialized.copy].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#uninitialized.copy">issues</a> in [uninitialized.copy].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

The specialized  algorithms [lib.specialized.algorithms] are specified
as having the general effect of invoking the following expression:

        </p>
            <pre>
new (static_cast&lt;void*&gt;(&amp;*i))
    typename iterator_traits&lt;ForwardIterator&gt;::value_type (x)

            </pre>
        <p>

This  expression is  ill-formed  when the  type  of the  subexpression
<code>&amp;*i</code> is some volatile-qualified <code>T</code>.

        </p>

<p><i>[
Batavia:  Lack of support for proposed resolution but agree there is a
defect.  Howard to look at wording.  Concern that move semantics
properly expressed if iterator returns rvalue.
]</i></p>


    

    <p><b>Proposed resolution:</b></p>
        <p>

In order  to allow these algorithms  to operate on  volatile storage I
propose to change the expression so as to make it well-formed even for
pointers  to volatile  types.  Specifically,  I propose  the following
changes to clauses 20 and 24. Change 20.6.4.1, p1 to read:

        </p>
            <pre>
<i>Effects</i>:

typedef typename iterator_traits&lt;ForwardIterator&gt;::pointer    pointer;
typedef typename iterator_traits&lt;ForwardIterator&gt;::value_type value_type;

for (; first != last; ++result, ++first)
    new (static_cast&lt;void*&gt;(const_cast&lt;pointer&gt;(&amp;*result))
        value_type (*first);

            </pre>
        <p>

change 20.6.4.2, p1 to read

        </p>
            <pre>
<i>Effects</i>:

typedef typename iterator_traits&lt;ForwardIterator&gt;::pointer    pointer;
typedef typename iterator_traits&lt;ForwardIterator&gt;::value_type value_type;

for (; first != last; ++result, ++first)
    new (static_cast&lt;void*&gt;(const_cast&lt;pointer&gt;(&amp;*first))
        value_type (*x);

            </pre>
        <p>

and change 20.6.4.3, p1 to read

        </p>
            <pre>
<i>Effects</i>:

typedef typename iterator_traits&lt;ForwardIterator&gt;::pointer    pointer;
typedef typename iterator_traits&lt;ForwardIterator&gt;::value_type value_type;

for (; n--; ++first)
    new (static_cast&lt;void*&gt;(const_cast&lt;pointer&gt;(&amp;*first))
        value_type (*x);

            </pre>
        <p>

In   addition,  since   there   is  no   partial  specialization   for
<code>iterator_traits&lt;volatile T*&gt;</code>  I propose to  add one
to parallel such specialization  for &lt;const T*&gt;. Specifically, I
propose to add the following text to the end of 24.3.1, p3:

        </p>
        <p>

and for pointers to volatile as 

        </p>
            <pre>
namespace std {
template&lt;class T&gt; struct iterator_traits&lt;volatile T*&gt; {
typedef ptrdiff_t difference_type;
typedef T value_type;
typedef volatile T* pointer;
typedef volatile T&amp; reference;
typedef random_access_iterator_tag iterator_category;
};
}

            </pre>
        <p>

Note that  the change to  <code>iterator_traits</code> isn't necessary
in order to implement the  specialized algorithms in a way that allows
them to operate on volatile  strorage. It is only necesassary in order
to specify  their effects in terms  of <code>iterator_traits</code> as
is  done here.   Implementations can  (and some  do) achieve  the same
effect by means of function template overloading.

        </p>
    



<hr>
<h3><a name="585"></a>585. facet error reporting</h3>
<p><b>Section:</b> 22.2 [locale.categories] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor, Paolo Carlini <b>Date:</b> 2006-06-22</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.categories">active issues</a> in [locale.categories].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.categories">issues</a> in [locale.categories].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

Section  22.2, paragraph 2  requires facet  <code>get()</code> members
that    take    an    <code>ios_base::iostate&amp;</code>    argument,
<code><i>err</i></code>,  to   ignore  the  (initial)   value  of  the
argument, but to set it to <code>ios_base::failbit</code> in case of a
parse error.

        </p>
        <p>

We  believe  there  are  a   few  minor  problems  with  this  blanket
requirement  in   conjunction  with   the  wording  specific   to  each
<code>get()</code> member function.

        </p>
        <p>

First,  besides <code>get()</code>  there are  other  member functions
with     a      slightly     different     name      (for     example,
<code>get_date()</code>). It's not completely clear that the intent of
the  paragraph  is  to  include  those  as  well,  and  at  least  one
implementation has interpreted the requirement literally.

        </p>
        <p>

Second,    the     requirement    to    "set     the    argument    to
<code>ios_base::failbit</code>  suggests that  the  functions are  not
permitted    to   set    it   to    any   other    value    (such   as
<code>ios_base::eofbit</code>,   or   even  <code>ios_base::eofbit   |
ios_base::failbit</code>).

        </p>
        <p>

However, 22.2.2.1.2, p5 (Stage  3 of <code>num_get</code> parsing) and
p6 (<code>bool</code> parsing)  specifies that the <code>do_get</code>
functions  perform <code><i>err</i> |=  ios_base::eofbit</code>, which
contradicts  the earlier  requirement to  ignore  <i>err</i>'s initial
value.

        </p>
        <p>

22.2.6.1.2,  p1  (the  Effects  clause of  the  <code>money_get</code>
facet's  <code>do_get</code>  member  functions) also  specifies  that
<code><i>err</i></code>'s initial  value be used to  compute the final
value  by  ORing  it  with  either  <code>ios_base::failbit</code>  or
with<code>ios_base::eofbit | ios_base::failbit</code>.

        </p>
    

    <p><b>Proposed resolution:</b></p>
        <p>

We believe the  intent is for all facet member  functions that take an
<code>ios_base::iostate&amp;</code> argument to:

        </p>
            <ul>
                <li>

ignore the initial value of the <code><i>err</i></code> argument,

                </li>
                <li>

reset <code><i>err</i></code>  to <code>ios_base::goodbit</code> prior
to any further processing,

                </li>
                <li>

and       set      either       <code>ios_base::eofbit</code>,      or
<code>ios_base::failbit</code>, or both in <code><i>err</i></code>, as
appropriate,  in response  to  reaching the  end-of-file  or on  parse
error, or both.

                </li>
            </ul>
        <p>

To that effect we propose to change 22.2, p2 as follows:

        </p>
        <p>

The  <i>put</i><del>()</del>  members  make  no  provision  for  error
reporting.   (Any  failures of  the  OutputIterator  argument must  be
extracted   from  the   returned  iterator.)    <ins>Unless  otherwise
specified, </ins>the <i>get</i><del>()</del>  members  <ins>that</ins>
take an  <code>ios_base::iostate&amp;</code> argument <del>whose value
they  ignore,  but  set  to  ios_base::failbit  in  case  of  a  parse
error.</del><ins>,   <code><i>err</i></code>,   start  by   evaluating
<code>err  =   ios_base::goodbit</code>,  and  may   subsequently  set
<i>err</i>     to     either     <code>ios_base::eofbit</code>,     or
<code>ios_base::failbit</code>,     or     <code>ios_base::eofbit    |
ios_base::failbit</code> in response to reaching the end-of-file or in
case of a parse error, or both, respectively.</ins>

        </p>
    
    
<p><i>[
Kona (2007): We need to change the proposed wording to clarify that the
phrase "the get members" actually denotes <tt>get()</tt>, <tt>get_date()</tt>, etc.
Proposed Disposition: Open
]</i></p>




<hr>
<h3><a name="588"></a>588. requirements on zero sized tr1::arrays and other details</h3>
<p><b>Section:</b> 23.2.1 [array] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Gennaro Prota <b>Date:</b> 2006-07-18</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#array">active issues</a> in [array].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#array">issues</a> in [array].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The wording used for section 23.2.1 [lib.array] seems to be subtly
ambiguous about zero sized arrays (N==0). Specifically:
</p>
<p>
* "An instance of array&lt;T, N&gt; stores N elements of type T, so that
[...]"
</p>
<p>
Does this imply that a zero sized array object stores 0 elements, i.e.
that it cannot store any element of type T? The next point clarifies
the rationale behind this question, basically how to implement begin()
and end():
</p>
<p>
* 23.2.1.5 [lib.array.zero], p2: "In the case that N == 0, begin() ==
end() == unique value."
</p>
<p>
What does "unique" mean in this context? Let's consider the following
possible implementations, all relying on a partial specialization:
</p>
<blockquote><pre>a)
    template&lt; typename T &gt;
    class array&lt; T, 0 &gt; {
    
        ....

        iterator begin()
        { return iterator( reinterpret_cast&lt; T * &gt;( this ) ); }
        ....

    };
</pre></blockquote>
<p>
This has been used in boost, probably intending that the return value
had to be unique to the specific array object and that array couldn't
store any T. Note that, besides relying on a reinterpret_cast, has
(more than potential) alignment problems.
</p>
<blockquote><pre>b)
    template&lt; typename T &gt;
    class array&lt; T, 0 &gt; {
    
        T t;

        iterator begin()
        { return iterator( &amp;t ); }
        ....

    };
</pre></blockquote>
<p>
This provides a value which is unique to the object and to the type of
the array, but requires storing a T. Also, it would allow the user to
mistakenly provide an initializer list with one element.
</p>
<p>
A slight variant could be returning *the* null pointer of type T
</p>
<blockquote><pre>    return static_cast&lt;T*&gt;(0);
</pre></blockquote>
<p>
In this case the value would be unique to the type array&lt;T, 0&gt; but not
to the objects (all objects of type array&lt;T, 0&gt; with the same value
for T would yield the same pointer value).
</p>
<p>
Furthermore this is inconsistent with what the standard requires from
allocation functions (see library issue 9).
</p>
<p>
c) same as above but with t being a static data member; again, the
value would be unique to the type, not to the object.
</p>
<p>
d) to avoid storing a T *directly* while disallowing the possibility
to use a one-element initializer list a non-aggregate nested class
could be defined
</p>
<blockquote><pre>    struct holder { holder() {} T t; } h;
</pre></blockquote>
<p>
and then begin be defined as
</p>
<blockquote><pre> iterator begin() { return &amp;h.t; }
</pre></blockquote>
<p>
But then, it's arguable whether the array stores a T or not.
Indirectly it does.
</p>
<p>
-----------------------------------------------------
</p>
<p>
Now, on different issues:
</p>
<p>
* what's the effect of calling assign(T&amp;) on a zero-sized array? There
seems to be only mention of front() and back(), in 23.2.1 [lib.array]
p4 (I would also suggest to move that bullet to section 23.2.1.5
[lib.array.zero], for locality of reference)
</p>
<p>
* (minor) the opening paragraph of 23.2.1 [lib.array] wording is a bit
inconsistent with that of other sequences: that's not a problem in
itself, but compare it for instance with "A vector is a kind of
sequence that supports random access iterators"; though the intent is
obvious one might argue that the wording used for arrays doesn't tell
what an array is, and relies on the reader to infer that it is what
the &lt;array&gt; header defines.
</p>
<p>
* it would be desiderable to have a static const data member of type
std::size_t, with value N, for usage as integral constant expression
</p>
<p>
* section 23.1 [lib.container.requirements] seem not to consider
fixed-size containers at all, as it says: "[containers] control
allocation and deallocation of these objects [the contained objects]
through constructors, destructors, *insert and erase* operations"
</p>
<p>
* max_size() isn't specified: the result is obvious but, technically,
it relies on table 80: "size() of the largest possible container"
which, again, doesn't seem to consider fixed size containers
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>


<p><i>[
Kona (2007): requirements on zero sized <tt>tr1::array</tt>s and other details
Issue 617: <tt>std::array</tt> is a sequence that doesn't satisfy the sequence
requirements? Alisdair will prepare a paper. Proposed Disposition: Open
]</i></p>





<hr>
<h3><a name="595"></a>595. TR1/C++0x: fabs(complex&lt;T&gt;) redundant / wrongly specified</h3>
<p><b>Section:</b> 26.3.7 [complex.value.ops] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Stefan Große Pawig <b>Date:</b> 2006-09-24</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
TR1 introduced, in the C compatibility chapter, the function
fabs(complex&lt;T&gt;):
</p>
<blockquote><pre>----- SNIP -----
8.1.1 Synopsis                                [tr.c99.cmplx.syn]

  namespace std {
  namespace tr1 {
[...]
  template&lt;class T&gt; complex&lt;T&gt; fabs(const complex&lt;T&gt;&amp; x);
  } // namespace tr1
  } // namespace std

[...]

8.1.8 Function fabs                          [tr.c99.cmplx.fabs]

1 Effects: Behaves the same as C99 function cabs, defined in
  subclause 7.3.8.1.
----- SNIP -----
</pre></blockquote>

<p>
The current C++0X draft document (n2009.pdf) adopted this
definition in chapter 26.3.1 (under the comment // 26.3.7 values)
and 26.3.7/7.
</p>
<p>
But in C99 (ISO/IEC 9899:1999 as well as the 9899:TC2 draft document
n1124), the referenced subclause reads
</p>

<blockquote><pre>----- SNIP -----
7.3.8.1 The cabs functions

  Synopsis

1 #include &lt;complex.h&gt;
  double cabs(double complex z);
  float cabsf(float complex z);
  long double cabsl(long double z);

  Description

2 The cabs functions compute the complex absolute value (also called
  norm, modulus, or magnitude) of z.

  Returns

3 The cabs functions return the complex absolute value.
----- SNIP -----
</pre></blockquote>

<p>
Note that the return type of the cabs*() functions is not a complex
type.  Thus, they are equivalent to the already well established
  template&lt;class T&gt; T abs(const complex&lt;T&gt;&amp; x);
(26.2.7/2 in ISO/IEC 14882:1998, 26.3.7/2 in the current draft
document n2009.pdf).
</p>
<p>
So either the return value of fabs() is specified wrongly, or fabs()
does not behave the same as C99's cabs*().
</p>

<b>Possible Resolutions</b>

<p>
This depends on the intention behind the introduction of fabs().
</p>
<p>
If the intention was to provide a /complex/ valued function that
calculates the magnitude of its argument, this should be
explicitly specified.  In TR1, the categorization under "C
compatibility" is definitely wrong, since C99 does not provide
such a complex valued function.
</p>
<p>
Also, it remains questionable if such a complex valued function
is really needed, since complex&lt;T&gt; supports construction and
assignment from real valued arguments.  There is no difference
in observable behaviour between
</p>
<blockquote><pre>  complex&lt;double&gt; x, y;
  y = fabs(x);
  complex&lt;double&gt; z(fabs(x));
</pre></blockquote>
<p>
and
</p>
<blockquote><pre>  complex&lt;double&gt; x, y;
  y = abs(x);
  complex&lt;double&gt; z(abs(x));
</pre></blockquote>
<p>
If on the other hand the intention was to provide the intended
functionality of C99, fabs() should be either declared deprecated
or (for C++0X) removed from the standard, since the functionality
is already provided by the corresponding overloads of abs().
</p>



<p><b>Proposed resolution:</b></p>

<p>
Change the synopsis in 26.3.1 [complex.synopsis]:
</p>

<blockquote><pre>template&lt;class T&gt; <del>complex&lt;</del>T<del>&gt;</del> fabs(const complex&lt;T&gt;&amp;);
</pre></blockquote>

<p>
Change 26.3.7 [complex.value.ops], p7:
</p>

<blockquote>
<pre>template&lt;class T&gt; <del>complex&lt;</del>T<del>&gt;</del> fabs(const complex&lt;T&gt;&amp; <i>x</i>);
</pre>
<blockquote>
<p>
-7- <i>Effects:</i> Behaves the same as C99 function <tt>cabs</tt>, defined in subclause 7.3.8.1.
</p>
</blockquote>
</blockquote>



<p><i>[
Kona (2007): Change the return type of <tt>fabs(complex)</tt> to <tt>T</tt>. 
Proposed Disposition: Ready
]</i></p>





<hr>
<h3><a name="596"></a>596. 27.8.1.3 Table 112 omits "a+" and "a+b" modes</h3>
<p><b>Section:</b> 27.8.1.4 [filebuf.members] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2006-09-26</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#filebuf.members">active issues</a> in [filebuf.members].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#filebuf.members">issues</a> in [filebuf.members].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In testing 27.8.1.4 [filebuf.members], Table 112 (in the latest N2009 draft), we invoke  
</p>
<blockquote><pre>   ostr.open("somename", ios_base::out | ios_base::in | ios_base::app)
</pre></blockquote>
<p>
and we expect the open to fail, because out|in|app is not listed in
Table 92, and just before the table we see very specific words:
</p>
<blockquote><p>
  If mode is not some combination of flags shown in the table 
  then the open fails.
</p></blockquote>
<p>
But the corresponding table in the C standard, 7.19.5.3, provides two
modes "a+" and "a+b", to which the C++ modes out|in|app and
out|in|app|binary would presumably apply.
</p>
<p>
We would like to argue that the intent of Table 112 was to match the
semantics of 7.19.5.3 and that the omission of "a+" and "a+b" was
unintentional.  (Otherwise there would be valid and useful behaviors
available in C file I/O which are unavailable using C++, for no
valid functional reason.)
</p>
<p>
We further request that the missing modes be explicitly restored to
the WP, for inclusion in C++0x.
</p>

<p><i>[
Martin adds:
]</i></p>


<p>
...besides "a+" and "a+b" the C++ table is also missing a row
for a lone app bit which in at least two current implementation
as well as in Classic Iostreams corresponds to the C stdio "a"
mode and has been traditionally documented as implying ios::out.
Which means the table should also have a row for in|app meaning
the same thing as "a+" already proposed in the issue.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add to the table "File open modes" in 27.8.1.4 [filebuf.members]:
</p>

<blockquote>
<table border="1">
<caption> File open modes</caption>
<tbody><tr>
<th colspan="5"><tt>ios_base</tt> Flag combination</th>
<th><tt>stdio</tt> equivalent</th>
</tr>
<tr>
<th><tt>binary</tt></th><th><tt>in</tt></th><th><tt>out</tt></th><th><tt>trunc</tt></th><th><tt>app</tt></th><th><tt>&nbsp;</tt></th>
</tr>

<tr>
<td>&nbsp;</td> <td>&nbsp;</td> <td><tt>+</tt></td> <td>&nbsp;</td> <td>&nbsp;</td> <td><tt>"w"</tt></td>
</tr>
<tr>
<td>&nbsp;</td> <td>&nbsp;</td> <td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>+</tt></td> <td><tt>"a"</tt></td>
</tr>
<tr>
<td>&nbsp;</td> <td>&nbsp;</td> <td>&nbsp;</td> <td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>"a"</tt></ins></td>
</tr>
<tr>
<td>&nbsp;</td> <td>&nbsp;</td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>"w"</tt></td>
</tr>
<tr>
<td>&nbsp;</td> <td><tt>+</tt></td> <td>&nbsp;</td> <td>&nbsp;</td> <td>&nbsp;</td> <td><tt>"r"</tt></td>
</tr>
<tr>
<td>&nbsp;</td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td>&nbsp;</td> <td><tt>"r+"</tt></td>
</tr>
<tr>
<td>&nbsp;</td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>"w+"</tt></td>
</tr>
<tr>
<td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>+</tt></ins></td> <td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>"a+"</tt></ins></td>
</tr>
<tr>
<td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td>&nbsp;</td> <td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>"a+"</tt></ins></td>
</tr>

<tr>
<td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>+</tt></td> <td>&nbsp;</td> <td>&nbsp;</td> <td><tt>"wb"</tt></td>
</tr>
<tr>
<td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>+</tt></td> <td><tt>"ab"</tt></td>
</tr>
<tr>
<td><ins><tt>+</tt></ins></td> <td>&nbsp;</td> <td>&nbsp;</td> <td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>"ab"</tt></ins></td>
</tr>
<tr>
<td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>"wb"</tt></td>
</tr>
<tr>
<td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td>&nbsp;</td> <td>&nbsp;</td> <td><tt>"rb"</tt></td>
</tr>
<tr>
<td><tt>+</tt></td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td>&nbsp;</td> <td><tt>"r+b"</tt></td>
</tr>
<tr>
<td><tt>+</tt></td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td><tt>+</tt></td> <td>&nbsp;</td> <td><tt>"w+b"</tt></td>
</tr><tr>
<td><ins><tt>+</tt></ins></td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>+</tt></ins></td> <td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>"a+b"</tt></ins></td>
</tr>
<tr>
<td><ins><tt>+</tt></ins></td> <td><ins><tt>+</tt></ins></td> <td>&nbsp;</td> <td>&nbsp;</td> <td><ins><tt>+</tt></ins></td> <td><ins><tt>"a+b"</tt></ins></td>
</tr>


</tbody></table>
</blockquote>



<p><i>[
Kona (2007) Added proposed wording and moved to Review.
]</i></p>





<hr>
<h3><a name="597"></a>597. Decimal: The notion of 'promotion' cannot be emulated by user-defined types.</h3>
<p><b>Section:</b> TRDecimal 3.2 [trdec.types.types] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Daveed Vandevoorde <b>Date:</b> 2006-04-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#trdec.types.types">active issues</a> in [trdec.types.types].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#trdec.types.types">issues</a> in [trdec.types.types].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In a private email, Daveed writes:
</p>
<blockquote>
<p>
I am not familiar with the C TR, but my guess is that the
class type approach still won't match a built-in type
approach because the notion of "promotion" cannot be
emulated by user-defined types.
</p>
<p>
Here is an example:
</p>
</blockquote>
<pre>
		 struct S {
		   S(_Decimal32 const&amp;);  // Converting constructor
		 };
		 void f(S);

		 void f(_Decimal64);

		 void g(_Decimal32 d) {
		   f(d);
		 }
</pre>

<blockquote>
<p>
If _Decimal32 is a built-in type, the call f(d) will likely
resolve to f(_Decimal64) because that requires only a
promotion, whereas f(S) requires a user-defined conversion.
</p>
<p>
If _Decimal32 is a class type, I think the call f(d) will be
ambiguous because both the conversion to _Decimal64 and the
conversion to S will be user-defined conversions with neither
better than the other.
</p>
</blockquote>
<p>
Robert comments:
</p>
<p>In general, a library of arithmetic types cannot exactly emulate the
behavior of the intrinsic numeric types. There are several ways to tell
whether an implementation of the decimal types uses compiler
intrinisics or a library. For example:
</p>
<pre>                 _Decimal32 d1;
                 d1.operator+=(5);  // If d1 is a builtin type, this won't compile.
</pre>
<p>
In preparing the decimal TR, we have three options:
</p>
<ol>
<li>require that the decimal types be class types</li>
<li>require that the decimal types be builtin types, like float and double</li>
<li>specify a library of class types, but allow enough implementor
latitude that a conforming implementation could instead provide builtin
types</li>
</ol>
<p>
We decided as a group to pursue option #3, but that approach implies
that implementations may not agree on the semantics of certain use
cases (first example, above), or on whether certain other cases are
well-formed (second example). Another potentially important problem is
that, under the present definition of POD, the decimal classes are not
POD types, but builtins will be.
</p>
<p>Note that neither example above implies any problems with respect to
C-to-C++ compatibility, since neither example can be expressed in C.
</p>


<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="606"></a>606. Decimal: allow narrowing conversions</h3>
<p><b>Section:</b> TRDecimal 3.2 [trdec.types.types] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2006-06-15</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#trdec.types.types">active issues</a> in [trdec.types.types].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#trdec.types.types">issues</a> in [trdec.types.types].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In c++std-lib-17205, Martin writes:
</p>
<blockquote><p>...was it a deliberate design choice to make narrowing
assignments ill-formed while permitting narrowing compound assignments?
For instance:
</p></blockquote>
<pre>      decimal32 d32;
      decimal64 d64;

      d32 = 64;     // error
      d32 += 64;    // okay
</pre>
<p>
In c++std-lib-17229, Robert responds:
</p>
<blockquote><p>It is a vestige of an old idea that I forgot to remove
from the paper. Narrowing assignments should be permitted. The bug is
that the converting constructors that cause narrowing should not be
explicit. Thanks for pointing this out.
</p></blockquote>

<p><b>Proposed resolution:</b></p>
<p>
1.  In "3.2.2 Class <code>decimal32</code>" synopsis, remove the <code>explicit</code> specifier from the narrowing conversions:
</p>
<pre>                // <i>3.2.2.2 conversion from floating-point type:</i>
                <del>explicit</del> decimal32(decimal64 <i>d64</i>);
                <del>explicit</del> decimal32(decimal128 <i>d128</i>);
</pre>
<p>
2.  Do the same thing in "3.2.2.2. Conversion from floating-point type."
</p>
<p>
3.  In "3.2.3 Class <code>decimal64</code>" synopsis, remove the <code>explicit</code> specifier from the narrowing conversion:
</p>
<pre>                // <i>3.2.3.2 conversion from floating-point type:</i>
                <del>explicit</del> decimal64(decimal128 <i>d128</i>);
</pre>
<p>
4.  Do the same thing in "3.2.3.2. Conversion from floating-point type."
</p>

<p><i>[
Redmond: We prefer explicit conversions for narrowing and implicit for widening.
]</i></p>






<hr>
<h3><a name="612"></a>612. numeric_limits::is_modulo insufficently defined</h3>
<p><b>Section:</b> 18.2.1.2 [numeric.limits.members] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Chris Jefferson <b>Date:</b> 2006-11-10</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#numeric.limits.members">issues</a> in [numeric.limits.members].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
18.2.1.2 55 states that "A type is modulo if it is possible to add two
positive numbers together and have a result that wraps around to a
third number that is less".
This seems insufficent for the following reasons:
</p>

<ol>
<li>Doesn't define what that value recieved is.</li>
<li>Doesn't state the result is repeatable</li>
<li> Doesn't require that doing addition, subtraction and other
operations on all values is defined behaviour.</li>
</ol>

<p><i>[
Batavia: Related to
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2144.pdf">N2144</a>.
Pete: is there an ISO definition of modulo?  Underflow on signed behavior is undefined.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
Suggest 18.2.1.2 [numeric.limits.members[numeric.limits.members], paragraph 57 is ammeded to:
</p>

<blockquote><p>
A type is modulo if<ins>,</ins> <del>it is possible to add two positive numbers
and have a result that wraps around to a third number that is less.</del>
<ins>given any operation involving +,- or * on values of that type whose value
would fall outside the range <tt>[min(), max()]</tt>, then the value returned
differs from the true value by an integer multiple of <tt>(max() - min() +
1)</tt>.</ins>
</p></blockquote>






<hr>
<h3><a name="614"></a>614. std::string allocator requirements still inconsistent</h3>
<p><b>Section:</b> 21.3 [basic.string] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Bo Persson <b>Date:</b> 2006-12-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#basic.string">active issues</a> in [basic.string].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#basic.string">issues</a> in [basic.string].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
This is based on N2134, where 21.3.1/2 states:
"... The Allocator object used shall be a copy of the Allocator object 
passed to the basic_string object's constructor or, if the constructor does 
not take an Allocator argument, a copy of a default-constructed Allocator 
object."
</p>
<p>
Section 21.3.2/1 lists two constructors:
</p>
<blockquote><pre>basic_string(const basic_string&lt;charT,traits,Allocator&gt;&amp; str );

basic_string(const basic_string&lt;charT,traits,Allocator&gt;&amp; str ,
             size_type pos , size_type n = npos,
             const Allocator&amp; a = Allocator());
</pre></blockquote>
<p>
and then says "In the first form, the Allocator value used is copied from 
str.get_allocator().", which isn't an option according to 21.3.1.
</p>
<p><i>[
Batavia:  We need blanket statement to the effect of:
]</i></p>


<ol>
<li>If an allocator is passed in, use it, or,</li>
<li>If a string is passed in, use its allocator.</li>
</ol>
<p><i>[
Review constructors and functions that return a string; make sure we follow these
rules (substr, operator+, etc.).  Howard to supply wording.
]</i></p>


<p><i>[
Bo adds:  The new container constructor which takes only a <tt>size_type</tt> is not
consistent with 23.1 [container.requirements], p9 which says in part:

<blockquote>
All other constructors for these container types take an
<tt>Allocator&amp;</tt> argument (20.1.2), an allocator whose value type
is the same as the container's value type. A copy of this argument is
used for any memory allocation performed, by these constructors and by
all member functions, during the lifetime of each container object.
</blockquote>
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="617"></a>617. std::array is a sequence that doesn't satisfy the sequence requirements?</h3>
<p><b>Section:</b> 23.2.1 [array] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Bo Persson <b>Date:</b> 2006-12-30</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#array">active issues</a> in [array].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#array">issues</a> in [array].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The <tt>&lt;array&gt;</tt> header is given under 23.2 [sequences].
23.2.1 [array]/paragraph 3 says:
</p>
<blockquote><p>
"Unless otherwise specified, all array operations are as described in
23.1 [container.requirements]".
</p></blockquote>
<p>
However, array isn't mentioned at all in section 23.1 [container.requirements].
In particular, Table 82 "Sequence requirements" lists several operations (insert, erase, clear) 
that std::array does not have in 23.2.1 [array].
</p>
<p>
Also, Table 83 "Optional sequence operations" lists several operations that 
std::array does have, but array isn't mentioned.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="618"></a>618. valarray::cshift() effects on empty array</h3>
<p><b>Section:</b> 26.5.2.7 [valarray.members] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Gabriel Dos Reis <b>Date:</b> 2007-01-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I would respectfully request an issue be opened with the intention to
clarify the wording for <tt>size() == 0</tt> for <tt>cshift</tt>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 26.5.2.7 [valarray.members], paragraph 10:
</p>

<blockquote>

<pre>valarray&lt;T&gt; cshift(int <i>n</i>) const;
</pre>

<blockquote>
<p>
This function returns an object of class <tt>valarray&lt;T&gt;</tt>, of
length <tt>size()</tt>, <del>each of whose elements <tt>I</tt> is
<tt>(*this)[(I + n ) % size()]</tt>. Thus, if element zero is taken as
the leftmost element, a positive value of <i>n</i> shifts the elements
circularly left <i>n</i> places.</del> <ins>that is a circular shift of <tt>*this</tt>. If
element zero is taken as the leftmost element, a non-negative value of
<i>n</i> shifts the elements circularly left <i>n</i> places and a
negative value of <i>n</i> shifts the elements circularly right
-<i>n</i> places.</ins>
</p>
</blockquote>
</blockquote>



<p><b>Rationale:</b></p>
<p>
We do not believe that there is any real ambiguity about what happens
when <tt>size() == 0</tt>, but we do believe that spelling this out as a C++
expression causes more trouble that it solves. The expression is
certainly wrong when <tt>n &lt; 0</tt>, since the sign of % with negative arguments
is implementation defined.
</p>


<p><i>[
Kona (2007) Changed proposed wording, added rationale and set to Review.
]</i></p>





<hr>
<h3><a name="620"></a>620. valid uses of empty valarrays</h3>
<p><b>Section:</b> 26.5.2.1 [valarray.cons] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#valarray.cons">active issues</a> in [valarray.cons].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#valarray.cons">issues</a> in [valarray.cons].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

The <i>Effects</i>  clause for the  default <code>valarray</code> ctor
suggests  that  it  is possible  to  increase  the  size of  an  empty
<code>valarray</code>  object   by  calling  other   non-const  member
functions of the class besides <code>resize()</code>. However, such an
interpretation would  be contradicted by  the requirement on  the copy
assignment  operator  (and  apparently   also  that  on  the  computed
assignments)  that the  assigned arrays  be  the same  size.  See  the
reflector discussion starting with c++std-lib-17871.

        </p>
        <p>

In  addition,  <i>Footnote</i> 280  uses  some questionable  normative
language.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

Reword the <i>Effects</i> clause and <i>Footnote 280</i> as follows (26.5.2.1 [valarray.cons]):

        </p>
        <blockquote>
            <p>

<code>valarray();</code>

            </p>
            <p>

<i>Effects</i>:      Constructs      an      object      of      class
<code>valarray&lt;T&gt;</code>,<sup>279)</sup>    which    has    zero
length<del> until it is passed into a library function as a modifiable
lvalue or through a non-constant this pointer</del>.<sup>280)</sup>

            </p>
            <p>

<ins><i>Postcondition</i>: <code>size() == 0</code>.</ins>

            </p>
            <p>

<i>Footnote  280</i>:  This default  constructor  is essential,  since
arrays  of  <code>valarray</code>  <del>are  likely to  prove  useful.
There  shall also  be  a way  to change  the  size of  an array  after
initialization;  this  is  supplied  by the  semantics</del>  <ins>may be
useful.   The  length  of  an  empty  array  can  be  increased  after
initialization  by  means</ins>  of the  <code>resize()</code>  member
function.

            </p>
        </blockquote>





<hr>
<h3><a name="621"></a>621. non-const copy assignment operators of helper arrays</h3>
<p><b>Section:</b> 26.5 [numarray] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#numarray">issues</a> in [numarray].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

The computed and  "fill" assignment operators of <code>valarray</code>
helper     array     class    templates     (<code>slice_array</code>,
<code>gslice_array</code>,         <code>mask_array</code>,        and
<code>indirect_array</code>) are const  member functions of each class
template     (the     latter    by     the     resolution    of  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#123">123</a>
since  they have reference  semantics and thus do  not affect
the state of  the object on which they are  called.  However, the copy
assignment  operators  of  these  class  templates,  which  also  have
reference semantics,  are non-const.   The absence of  constness opens
the door to speculation about whether they really are intended to have
reference semantics (existing implementations vary widely).

        </p>

<p>
Pre-Kona, Martin adds:
</p>

<p>
I realized that adding the const qualifier to the
functions as I suggested would break the const correctness of the
classes. A few possible solutions come to mind:
</p>

<ol>
<li>Add the const qualifier to the return types of these functions.</li>
<li>Change the return type of all the functions to void to match
the signatures of all the other assignment operators these classes
define.</li>
<li>Prohibit the copy assignment of these classes by declaring the
copy assignment operators private (as is done and documented by
some implementations).</li>
</ol>



<p><b>Proposed resolution:</b></p>
        <p>

Declare  the  copy  assignment  operators  of all  four  helper  array
class templates const.

        </p>
        <p>

Specifically,  make the following edits:

        </p>
        <p>

Change     the    signature     in     26.5.5 [template.slice.array]    and
26.5.5.1 [slice.arr.assign] as follows:

        </p>
        <blockquote><pre>
<code><ins>const</ins> slice_array&amp; operator= (const slice_array&amp;)<ins> const</ins>;</code>

        </pre></blockquote>
        <p>

Change     the     signature     in    26.5.7 [template.gslice.array]     and
26.5.7.1 [gslice.array.assign] as follows:

        </p>
        <blockquote><pre>
<code><ins>const</ins> gslice_array&amp; operator= (const gslice_array&amp;)<ins> const</ins>;</code>

        </pre></blockquote>
        <p>

Change the  signature in 26.5.8 [template.mask.array]  and 26.5.8.1 [mask.array.assign] as
follows:

        </p>
        <blockquote><pre>
<code><ins>const</ins> mask_array&amp; operator= (const mask_array&amp;)<ins> const</ins>;</code>

        </pre></blockquote>
        <p>

Change     the     signature     in    26.5.9 [template.indirect.array] and
26.5.9.1 [indirect.array.assign] as follows:

        </p>
        <blockquote><pre>
<code><ins>const</ins> indirect_array&amp; operator= (const indirect_array&amp;)<ins> const</ins>;</code>

        </pre></blockquote>


<p><i>[
Kona (2007) Added const qualification to the return types and set to Ready.
]</i></p>





<hr>
<h3><a name="622"></a>622. behavior of <code>filebuf</code> dtor and <code>close</code> on error</h3>
<p><b>Section:</b> 27.8.1.17 [fstream.members] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

<code>basic_filebuf</code>  dtor is  specified to  have  the following
straightforward effects:

        </p>
        <blockquote><p>

<i>Effects</i>:       Destroys      an      object       of      class
<code>basic_filebuf</code>. Calls <code>close()</code>.

        </p></blockquote>
        <p>

<code>close()</code> does a lot of potentially complicated processing,
including calling <code>overflow()</code> to write out the termination
sequence  (to   bring  the  output  sequence  to   its  initial  shift
state). Since  any of the  functions called during the  processing can
throw an exception, what should the  effects of an exception be on the
dtor? Should the  dtor catch and swallow it or  should it propagate it
to the caller?  The text doesn't  seem to provide any guidance in this
regard  other  than  the  general  restriction on  throwing  (but  not
propagating)  exceptions  from   destructors  of  library  classes  in
17.4.4.8 [res.on.exception.handling].

        </p>
        <p>

Further,  the last thing  <code>close()</code> is  specified to  do is
call <code>fclose()</code> to close the <code>FILE</code> pointer. The
last sentence of the <i>Effects</i> clause reads:

        </p>
        <blockquote><p>

...   If    any   of    the   calls   to    <code>overflow</code>   or
<code>std::fclose</code> fails then <code>close</code> fails.

        </p></blockquote>
        <p>

This  suggests that  <code>close()</code>  might be  required to  call
<code>fclose()</code>   if  and  only   if  none   of  the   calls  to
<code>overflow()</code> fails, and avoid closing the <code>FILE</code>
otherwise. This  way, if  <code>overflow()</code> failed to  flush out
the data, the caller  would have  the opportunity to  try to  flush it
again (perhaps  after trying  to deal with  whatever problem  may have
caused the failure), rather than losing it outright.

        </p>
        <p>

On the other hand,  the function's <i>Postcondition</i> specifies that
<code>is_open() ==  false</code>, which  suggests that it  should call
<code>fclose()</code>       unconditionally.       However,      since
<i>Postcondition</i> clauses  are specified for many  functions in the
standard,  including constructors  where they  obviously  cannot apply
after an  exception, it's not clear  whether this <i>Postcondition</i>
clause is intended to apply even after an exception.

        </p>
        <p>

It  might  be worth  noting  that  the  traditional behavior  (Classic
Iostreams  <code>fstream::close()</code> and  C <code>fclose()</code>)
is  to  close  the  <code>FILE</code> unconditionally,  regardless  of
errors.

        </p>

<p><i>[
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#397">397</a> and <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#418">418</a> for related issues.
]</i></p>




<p><b>Proposed resolution:</b></p>
        <p>

After discussing this  on the reflector (see the  thread starting with
c++std-lib-17650) we propose that <code>close()</code> be clarified to
match the traditional behavior, that is to close the <code>FILE</code>
unconditionally,  even after  errors or  exceptions.  In  addition, we
propose the dtor description be amended so as to explicitly require it
to catch and swallow any exceptions thrown by <code>close()</code>.

        </p>
        <p>

Specifically,   we   propose   to   make  the   following   edits   in
27.8.1.4 [filebuf.members]:

        </p>
        <blockquote>
            <pre>
<code>basic_filebuf&lt;charT,traits&gt;* close();</code>

            </pre>
            <p>

<i>Effects</i>:  If <code>is_open()  == false</code>,  returns  a null
pointer.        If      a       put      area       exists,      calls
<code>overflow(traits::eof())</code> to flush  characters. If the last
virtual   member  function   called  on   <code>*this</code>  (between
<code>underflow</code>,  <code>overflow</code>,  <code>seekoff</code>,
and   <code>seekpos</code>)  was   <code>overflow</code>   then  calls
<code>a_codecvt.unshift</code> (possibly several times) to determine a
termination   sequence,    inserts   those   characters    and   calls
<code>overflow(traits::eof())</code>  again.  Finally<ins>, regardless
of whether  any of the preceding  calls fails or  throws an exception,
the  function</ins> <del>it</del>  closes   the  file   ("as   if"  by   calling
<code>std::fclose(file)</code>).<sup>334)</sup>  If any  of  the calls
<ins>made    by   the    function</ins><del>to   <code>overflow</code>
or</del><ins>,  including  </ins><code>std::fclose</code><ins>, </ins>
fails then <code>close</code> fails<ins>  by returning a null pointer.
If one of these calls throws an exception, the exception is caught and
rethrown after closing the file.</ins>

            </p>
        </blockquote>
        <p>

And to make the following edits in 27.8.1.2 [filebuf.cons].

        </p>
        <blockquote>
            <pre>
<code>virtual ~basic_filebuf();</code>

            </pre>
            <p>

<i>Effects</i>:       Destroys      an      object       of      class
<code>basic_filebuf&lt;charT,traits&gt;</code>.                   Calls
<code>close()</code>.    <ins>If  an   exception  occurs   during  the
destruction of the object, including the call to <code>close()</code>,
the     exception    is     caught    but     not     rethrown    (see
17.4.4.8 [res.on.exception.handling]).</ins>

            </p>
        </blockquote>





<hr>
<h3><a name="623"></a>623. <code>pubimbue</code> forbidden to call <code>imbue</code></h3>
<p><b>Section:</b> 27.1.1 [iostream.limits.imbue] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

27.1.1 [iostream.limits.imbue]  specifies  that  "no  function  described  in
clause 27 except  for <code>ios_base::imbue</code> causes any instance
of                   <code>basic_ios::imbue</code>                  or
<code>basic_streambuf::imbue</code> to be called."

        </p>
        <p>

That      contradicts      the      <i>Effects</i>     clause      for
<code>basic_streambuf::pubimbue()</code>  which requires  the function
to do just that: call <code>basic_streambuf::imbue()</code>.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

To    fix   this,    rephrase    the   sentence    above   to    allow
<code>pubimbue</code> to do what  it was designed to do. Specifically.
change 27.1.1 [iostream.limits.imbue], p1 to read:

        </p>
        <blockquote><p>

No     function    described     in    clause     27     except    for
<code>ios_base::imbue</code>  <ins>and <code>basic_filebuf::pubimbue</code></ins>
causes    any    instance    of    <code>basic_ios::imbue</code>    or
<code>basic_streambuf::imbue</code> to be called. ...

        </p></blockquote>





<hr>
<h3><a name="624"></a>624. <code>valarray</code> assignment and arrays of unequal length</h3>
<p><b>Section:</b> 26.5.2.2 [valarray.assign] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

The behavior of the  <code>valarray</code> copy assignment operator is
defined only when both sides have  the same number of elements and the
spec is explicit about assignments of arrays of unequal lengths having
undefined behavior.

        </p>
        <p>

However, the generalized  subscripting assignment operators overloaded
on <code>slice_array</code>  et al (26.5.2.2 [valarray.assign])  don't have any
such restriction, leading  the reader to believe that  the behavior of
these  overloads is  well defined  regardless  of the  lengths of  the
arguments.

        </p>
        <p>

For example,  based on  the reading  of the spec  the behavior  of the
snippet below can be expected to be well-defined:

        </p>
        <pre>    const std::slice from_0_to_3 (0, 3, 1);   // refers to elements 0, 1, 2
    const std::valarray&lt;int&gt; a (1, 3);        // a = { 1, 1, 1 }
    std::valarray&lt;int&gt;       b (2, 4);        // b = { 2, 2, 2, 2 }

    b = a [from_0_to_3];
        </pre>
        <p>

In practice, <code>b</code> may end up being <code>{ 1, 1, 1 }</code>,
<code>{  1,  1, 1,  2  }</code>,  or  anything else,  indicating  that
existing implementations vary.

        </p>

<p>
Quoting from Section 3.4, Assignment operators, of Al Vermeulen's
Proposal for Standard C++ Array Classes (see c++std-lib-704;
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1993/N0308.asc">N0308</a>):
</p>
<blockquote><p>
  ...if the size of the array on the right hand side of the equal
  sign differs from the size of the array on the left, a run time
  error occurs. How this error is handled is implementation
  dependent; for compilers which support it, throwing an exception
  would be reasonable.
</p></blockquote>

<p>
And see more history in
<a href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/1993/N0280.pdf">N0280</a>.
</p>

        <p>

It has  been argued in  discussions on the committee's  reflector that
the semantics of all <code>valarray</code> assignment operators should
be permitted to be undefined unless  the  length  of the arrays  being
assigned is the same as the length of the one being assigned from. See
the thread starting at c++std-lib-17786.

        </p>
        <p>

In order  to reflect  such views, the  standard must specify  that the
size of the  array referred to by the argument  of the assignment must
match the size of the array  under assignment, for example by adding a
<i>Requires</i> clause to 26.5.2.2 [valarray.assign] as follows:

        </p>
        <blockquote><p>

<i>Requires</i>: The length of the  array to which the argument refers
equals <code>size()</code>.

        </p></blockquote>

        <p>

Note that it's  far from clear that such leeway  is necessary in order
to implement <code>valarray</code> efficiently.

        </p>


<p><b>Proposed resolution:</b></p>
<p>
Insert new paragraph into 26.5.2.2 [valarray.assign]:
</p>

<blockquote>
<pre>valarray&lt;T&gt;&amp; operator=(const slice_array&lt;T&gt;&amp;); 
valarray&lt;T&gt;&amp; operator=(const gslice_array&lt;T&gt;&amp;); 
valarray&lt;T&gt;&amp; operator=(const mask_array&lt;T&gt;&amp;); 
valarray&lt;T&gt;&amp; operator=(const indirect_array&lt;T&gt;&amp;);
</pre>
<blockquote>
<p><ins>
<i>Requires</i>: The length of the  array to which the argument refers
equals <code>size()</code>.
</ins></p>
<p>
These operators allow the results of a generalized subscripting operation to be assigned directly to a <tt>valarray</tt>.
</p>
</blockquote>
</blockquote>





<hr>
<h3><a name="625"></a>625. mixed up <i>Effects</i> and <i>Returns</i> clauses</h3>
<p><b>Section:</b> 17 [library] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#library">issues</a> in [library].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

Many  member functions  of  <code>basic_string</code> are  overloaded,
with  some of  the  overloads taking  a <code>string</code>  argument,
others  <code>value_type*</code>,  others <code>size_type</code>,  and
others still <code>iterators</code>. Often, the requirements on one of
the   overloads  are   expressed  in   the  form   of  <i>Effects</i>,
<i>Throws</i>,      and     in      the     Working      Paper     
(<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2134.pdf">N2134</a>)
also <i>Remark</i> clauses,  while those on the rest  of the overloads
via a reference to this overload and using a <i>Returns</i> clause.

        </p><p>
        </p>

The  difference between  the two  forms of  specification is  that per
17.3.1.3 [structure.specifications],  p3,  an  <i>Effects</i> clause  specifies
<i>"actions  performed  by the  functions,"</i>  i.e., its  observable
effects,  while a <i>Returns</i>  clause is  <i>"a description  of the
return  value(s)   of  a  function"</i>  that  does   not  impose  any
requirements on the function's observable effects.

        <p>
        </p>

Since only  <i>Notes</i> are explicitly defined to  be informative and
all  other paragraphs  are explicitly  defined to  be  normative, like
<i>Effects</i> and <i>Returns</i>,  the new <i>Remark</i> clauses also
impose normative requirements.

        <p>
        </p>

So  by this  strict  reading of  the  standard there  are some  member
functions of  <code>basic_string</code> that are required  to throw an
exception under  some conditions or use specific  traits members while
many other otherwise equivalent overloads, while obliged to return the
same  values, aren't required  to follow  the exact  same requirements
with regards to the observable effects.

        <p>
        </p>

Here's an example of this  problem that was precipitated by the change
from informative Notes to normative <i>Remark</i>s (presumably made to
address <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#424">424</a>):

        <p>
        </p>

In the Working  Paper, <code>find(string, size_type)</code> contains a
<i>Remark</i>  clause (which  is  just a  <i>Note</i>  in the  current
standard) requiring it to use <code>traits::eq()</code>.

        <p>
        </p>

<code>find(const  charT  *s,  size_type  pos)</code> is  specified  to
return  <code>find(string(s), pos)</code>  by a  <i>Returns</i> clause
and so  it is not required to  use <code>traits::eq()</code>. However,
the Working  Paper has  replaced the original  informative <i>Note</i>
about   the  function   using  <code>traits::length()</code>   with  a
normative  requirement  in  the   form  of  a  <i>Remark</i>.  Calling
<code>traits::length()</code> may be  suboptimal, for example when the
argument is a  very long array whose initial  substring doesn't appear
anywhere in <code>*this</code>.

        <p>
        </p>

Here's another  similar example,  one that existed  even prior  to the
introduction of <i>Remark</i>s:

        <p>
        </p>

<code> insert(size_type  pos, string, size_type,  size_type)</code> is
required   to   throw   <code>out_of_range</code>   if   <code>pos   &gt;
size()</code>.

        <p>
        </p>

<code>insert(size_type pos, string  str)</code> is specified to return
<code>insert(pos, str, 0, npos)</code>  by a <i>Returns</i> clause and
so its  effects when <code>pos  &gt; size()</code> are  strictly speaking
unspecified.

        
        <p>

I  believe  a  careful   review  of  the  current  <i>Effects</i>  and
<i>Returns</i>  clauses  is  needed  in  order to  identify  all  such
problematic cases. In  addition, a review of the  Working Paper should
be done to make sure that the newly introduced normative <i>Remark</i>
clauses do not impose  any undesirable normative requirements in place
of the original informative <i>Notes</i>.

        </p>
<p><i>[
Batavia:  Alan and Pete to work.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="626"></a>626. new <i>Remark</i> clauses not documented</h3>
<p><b>Section:</b> 17.3.1.3 [structure.specifications] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-20</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#structure.specifications">issues</a> in [structure.specifications].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

The <i>Remark</i> clauses newly  introduced into the Working Paper 
(<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2134.pdf">N2134</a>)
are  not mentioned  in  17.3.1.3 [structure.specifications] where  we list  the
meaning  of <i>Effects</i>, <i>Requires</i>,  and other  clauses (with
the exception  of <i>Notes</i> which are documented  as informative in
17.3.1.1 [structure.summary], p2, and which they replace in many cases).

        </p>
        <p>

Propose add a bullet for <i>Remarks</i> along with a brief description.

        </p>
<p><i>[
Batavia:  Alan and Pete to work.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="627"></a>627. Low memory and exceptions</h3>
<p><b>Section:</b> 18.5.1.1 [new.delete.single] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> P.J. Plauger <b>Date:</b> 2007-01-23</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#new.delete.single">issues</a> in [new.delete.single].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I recognize the need for nothrow guarantees in the exception reporting
mechanism, but I strongly believe that implementors also need an escape hatch
when memory gets really low. (Like, there's not enough heap to construct and
copy exception objects, or not enough stack to process the throw.) I'd like to
think we can put this escape hatch in 18.5.1.1 [new.delete.single],
<tt>operator new</tt>, but I'm not sure how to do it. We need more than a
footnote, but the wording has to be a bit vague. The idea is that if
<tt>new</tt> can't allocate something sufficiently small, it has the right to
<tt>abort</tt>/call <tt>terminate</tt>/call <tt>unexpected</tt>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="629"></a>629. complex<t> insertion and locale dependence</t></h3>
<p><b>Section:</b> 26.3.6 [complex.ops] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Gabriel Dos Reis <b>Date:</b> 2007-01-28</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#complex.ops">issues</a> in [complex.ops].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
is there an issue opened for (0,3) as complex number with
the French local?  With the English local, the above parses as an
imaginery complex number.  With the French locale it parses as a
real complex number.
</p>

<p>
Further notes/ideas from the lib-reflector, messages 17982-17984:
</p>

<blockquote>
<p>
Add additional entries in num_punct to cover the complex separator (French would be ';').
</p>
<p>
Insert a space before the comma, which should eliminate the ambiguity.
</p>
<p>
Solve the problem for ordered sequences in general, perhaps with a
dedicated facet.  Then complex should use that solution.
</p>
</blockquote>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="630"></a>630. arrays of valarray</h3>
<p><b>Section:</b> 26.5.2.1 [valarray.cons] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-01-28</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#valarray.cons">active issues</a> in [valarray.cons].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#valarray.cons">issues</a> in [valarray.cons].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
        <p>

Section 26.1 [numeric.requirements], p1     suggests     that     a
<code>valarray</code>  specialization on  a  type <code>T</code>  that
satisfies  the requirements enumerated  in the  paragraph is  itself a
valid  type   on  which  <code>valarray</code>   may  be  instantiated
(Footnote       269        makes       this       clear).        I.e.,
<code>valarray&lt;valarray&lt;T&gt;  &gt;</code> is  valid as  long as
<code>T</code>   is   valid.    However,  since   implementations   of
<code>valarray</code> are permitted to initialize storage allocated by
the class by  invoking the default ctor of  <code>T</code> followed by
the    copy    assignment    operator,   such    implementations    of
<code>valarray</code>   wouldn't  work  with   (perhaps  user-defined)
specializations of <code>valarray</code> whose assignment operator had
undefined behavior when the size of its argument didn't match the size
of <code>*this</code>.  By <i>"wouldn't work"</i> I mean that it would
be  impossible  to resize  such  an array  of  arrays  by calling  the
<code>resize()</code> member  function on it if the  function used the
copy  assignment operator  after constructing  all elements  using the
default  ctor (e.g.,  by invoking  <code>new  value_type[N]</code>) to
obtain default-initialized storage) as it's permitted to do.

        </p>
        <p>

Stated      more     generally,      the      problem     is      that
<code>valarray&lt;valarray&lt;T&gt;  &gt;::resize(size_t)</code> isn't
required or  guaranteed to have well-defined semantics  for every type
<code>T</code>     that      satisfies     all     requirements     in
26.1 [numeric.requirements].

        </p>
        <p>

I  believe  this  problem  was  introduced  by  the  adoption  of  the
resolution                outlined                in                <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1996/N0857.asc">N0857</a>,
<i>Assignment  of  valarrays</i>,  from  1996.   The  copy  assignment
operator  of  the original  numerical  array  classes  proposed in  <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1993/N0280.pdf">N0280</a>,
as      well       as      the      one       proposed      in      <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1993/N0308.asc">N0308</a>
(both  from 1993), had  well-defined semantics  for arrays  of unequal
size (the  latter explicitly  only when <code>*this</code>  was empty;
assignment of non empty arrays of unequal size was a runtime error).

        </p>
        <p>

The  justification for  the  change given  in  N0857 was the "loss  of
performance [deemed]  only significant  for very simple  operations on
small arrays or for architectures with very few registers."

        </p>
        <p>

Since tiny  arrays on a  limited subset of hardware  architectures are
likely  to  be  an   exceedingly  rare  case  (despite  the  continued
popularity of  x86) I  propose to revert  the resolution and  make the
behavior    of   all   <code>valarray</code>    assignment   operators
well-defined even  for non-conformal  arrays (i.e., arrays  of unequal
size).   I have implemented  this change  and measured  no significant
degradation  in performance in  the common  case (non-empty  arrays of
equal size).  I  have measured a 50% (and in  some cases even greater)
speedup  in the  case of  assignments to  empty arrays  versus calling
<code>resize()</code>  first followed  by  an invocation  of the  copy
assignment operator.

        </p>


<p><b>Proposed resolution:</b></p>
        <p>

Change 26.5.2.2 [valarray.assign], p1 as follows:

        </p>
        <blockquote>
            <p>
                <code>

valarray&lt;T&gt;&amp; operator=(const valarray&lt;T&gt;&amp;<ins> x</ins>);

                </code>
            </p>
            <p>

-1- Each element of the <code>*this</code> array is assigned the value
of  the  corresponding  element   of  the  argument  array.   <del>The
resulting behavior is undefined if </del><ins>When </ins>the length of
the  argument  array  is  not   equal  to  the  length  of  the  *this
array<del>.</del><ins>  resizes  <code>*this</code>  to make  the  two
arrays     the      same     length,     as      if     by     calling
<code>resize(x.size())</code>, before performing the assignment.</ins>

            </p>
        </blockquote>
        <p>

And  add a new  paragraph just  below paragraph  1 with  the following
text:

        </p>
        <blockquote>
            <p>

<ins>-2- <i>Postcondition</i>: <code>size() == x.size()</code>.</ins>

            </p>
        </blockquote>
        <p>

Also add the following paragraph to 26.5.2.2 [valarray.assign], immediately after p4:

        </p>
        <blockquote>
            <p>

<ins>-?- When the length,  <i><code>N</code></i> of the array referred
to by the  argument is not equal to  the length of <code>*this</code>,
the  operator resizes <code>*this</code>  to make  the two  arrays the
same  length, as if  by calling  <code>resize(<i>N</i>)</code>, before
performing the assignment.</ins>

            </p>
        </blockquote>


<p><i>[
Kona (2007): Gaby to propose wording for an alternative resolution in
which you can assign to a <tt>valarray</tt> of size 0, but not to any other
<tt>valarray</tt> whose size is unequal to the right hand side of the assignment.
]</i></p>





<hr>
<h3><a name="631"></a>631. conflicting requirements for <tt>BinaryPredicate</tt></h3>
<p><b>Section:</b> 25 [algorithms] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> James Kanze <b>Date:</b> 2007-01-31</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#algorithms">issues</a> in [algorithms].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The general requirements for <tt><tt>BinaryPredicate</tt></tt> (in 25 [algorithms]/8) contradict the implied specific requirements for
some functions. In particular, it says that:
</p>

<blockquote><p>
[...] if an algorithm takes <tt>BinaryPredicate <i>binary_pred</i></tt>
as its argument and <tt><i>first1</i></tt> and <i>first2</i> as its
iterator arguments, it should work correctly in the construct <tt>if
(binary_pred (*<i>first1</i> , *<i>first2</i> )){...}</tt>.
<tt>BinaryPredicate</tt> always takes the first iterator type as its
first argument, that is, in those cases when <tt>T <i>value</i></tt> is
part of the signature, it should work correctly in the context of <tt>if
(binary_pred (*<i>first1</i> , <i>value</i>)){...}</tt>.
</p></blockquote>

<p>
In the description of <tt>upper_bound</tt> (25.3.3.2 [upper.bound]/2), however, the use is described as
"<tt>!comp(<i>value</i>, <i>e</i>)</tt>", where <tt><i>e</i></tt> is an
element of the sequence (a result of dereferencing
<tt>*<i>first</i></tt>).
</p>

<p>
In the description of <tt>lexicographical_compare</tt>, we have both
"<tt>*<i>first1</i> &lt; *<i>first2</i></tt>" and "<tt>*<i>first2</i>
&lt; *<i>first1</i></tt>" (which presumably implies "<tt>comp(
*<i>first1</i>, *<i>first2</i> )</tt>" and "<tt>comp( *<i>first2</i>,
*<i>first1</i> )</tt>".
</p>

<p><i>[
Toronto:  Moved to Open.  ConceptGCC seems to get <tt>lower_bound</tt>
and <tt>upper_bound</tt> to work withoutt these changes.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
Logically, the <tt>BinaryPredicate</tt> is used as an ordering
relationship, with the semantics of "less than".  Depending on the
function, it may be used to determine equality, or any of the inequality
relationships; doing this requires being able to use it with either
parameter first.  I would thus suggest that the requirement be:
</p>

<blockquote><p>
[...] <tt>BinaryPredicate</tt> always takes the first iterator
<tt>value_type</tt> as one of its arguments, it is unspecified which. If
an algorithm takes <tt>BinaryPredicate <i>binary_pred</i></tt> as its
argument and <tt><i><i>first1</i></i></tt> and <i>first2</i> as its
iterator arguments, it should work correctly both in the construct
<tt>if (binary_pred (*<i>first1</i> , *<i>first2</i> )){...}</tt> and
<tt>if (binary_pred (*<i>first2</i>, *<i>first1</i>)){...}</tt>.  In
those cases when <tt>T <i>value</i></tt> is part of the signature, it
should work correctly in the context of <tt>if (binary_pred
(*<i>first1</i> , <i>value</i>)){...}</tt> and of <tt>if (binary_pred
(<i>value</i>, *<i>first1</i>)){...}</tt>. [<i>Note:</i> if the two
types are not identical, and neither is convertable to the other, this
may require that the <tt>BinaryPredicate</tt> be a functional object
with two overloaded <tt>operator()()</tt> functions. <i>--end note</i>]
</p></blockquote>

<p>
Alternatively, one could specify an order for each function. IMHO, this
would be more work for the committee, more work for the implementors,
and of no real advantage for the user: some functions, such as
<tt>lexicographical_compare</tt> or <tt>equal_range</tt>, will still require both
functions, and it seems like a much easier rule to teach that both
functions are always required, rather than to have a complicated list of
when you only need one, and which one.
</p>





<hr>
<h3><a name="632"></a>632. Time complexity of size() for std::set</h3>
<p><b>Section:</b> 23.1 [container.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Lionel B <b>Date:</b> 2007-02-01</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#container.requirements">active issues</a> in [container.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#container.requirements">issues</a> in [container.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
A recent news group discussion:
</p>
<blockquote>
<p>
Anyone know if the Standard has anything to say about the time complexity
of size() for std::set?   I need to access a set's size (/not/ to know if it is empty!) heavily
during an algorithm and was thus wondering whether I'd be better off
tracking the size "manually" or whether that'd be pointless.
</p>
<p>
That would be pointless. size() is O(1).
</p>
<p>
Nit: the standard says "should" have constant time. Implementations may take
license to do worse. I know that some do this for <tt>std::list&lt;&gt;</tt> as a part of
some trade-off with other operation.
</p>

<p>
I was aware of that, hence my reluctance to use size() for std::set.
</p>
<p>
However, this reason would not apply to <tt>std::set&lt;&gt;</tt> as far as I can see.
</p>
<p>
Ok, I guess the only option is to try it and see...
</p>
</blockquote>

<p>
If I have any recommendation to the C++ Standards Committee it is that
implementations must (not "should"!) document clearly[1], where known, the
time complexity of *all* container access operations.
</p>
<p>
[1] In my case (gcc 4.1.1) I can't swear that the time complexity of size()
for std::set is not documented... but if it is it's certainly well hidden
away.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>


<p><i>[
Kona (2007): This issue affects all the containers. We'd love to see a
paper dealing with the broad issue. We think that the complexity of the
<tt>size()</tt> member of every container -- except possibly <tt>list</tt> -- should be
O(1). Alan has volunteered to provide wording.
]</i></p>





<hr>
<h3><a name="635"></a>635. domain of <tt>allocator::address</tt></h3>
<p><b>Section:</b> 20.1.2 [allocator.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-02-08</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#allocator.requirements">active issues</a> in [allocator.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#allocator.requirements">issues</a> in [allocator.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The table of allocator requirements in 20.1.2 [allocator.requirements] describes
<tt>allocator::address</tt> as:
</p>
<blockquote><pre>a.address(r)
a.address(s)
</pre></blockquote>
<p>
where <tt>r</tt> and <tt>s</tt> are described as:
</p>
<blockquote><p>
a value of type <tt>X::reference</tt> obtained by the expression <tt>*p</tt>. 
</p></blockquote>

<p>
and <tt>p</tt> is 
</p>

<blockquote><p>
a value of type <tt>X::pointer</tt>, obtained by calling <tt>a1.allocate</tt>, 
where <tt>a1 == a</tt>
</p></blockquote>

<p>
This all implies that to get the address of some value of type <tt>T</tt> that
value must have been allocated by this allocator or a copy of it.
</p>

<p>
However sometimes container code needs to compare the address of an external value of
type <tt>T</tt> with an internal value.  For example <tt>list::remove(const T&amp; t)</tt>
may want to compare the address of the external value <tt>t</tt> with that of a value
stored within the list.  Similarly <tt>vector</tt> or <tt>deque insert</tt> may
want to make similar comparisons (to check for self-referencing calls).
</p>

<p>
Mandating that <tt>allocator::address</tt> can only be called for values which the
allocator allocated seems overly restrictive.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change 20.1.2 [allocator.requirements]:
</p>

<blockquote>
<p>
<tt>r</tt> : a value of type <tt>X::reference</tt> <del>obtained by the expression *p</del>.
</p>
<p>
<tt>s</tt> : a value of type <tt>X::const_reference</tt> <del>obtained by the 
expression <tt>*q</tt> or by conversion from a value <tt>r</tt></del>.
</p>
</blockquote>

<p><i>[
post Oxford:  This would be rendered NAD Editorial by acceptance of
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2257.html">N2257</a>.
]</i></p>


<p><i>[
Kona (2007):  This issue is section 8 of N2387.  There was some discussion of it but
no resolution to this issue was recorded.  Moved to Open.
]</i></p>







<hr>
<h3><a name="638"></a>638. deque end invalidation during erase</h3>
<p><b>Section:</b> 23.2.2.3 [deque.modifiers] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Steve LoBasso <b>Date:</b> 2007-02-17</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The standard states at 23.2.2.3 [deque.modifiers]/4:
</p>
<blockquote><pre>deque erase(...)
</pre>
 <p>
<i>Effects:</i> ... An erase at either end of the deque invalidates only
the iterators and the references to the erased elements.
</p>
</blockquote>
<p>
This does not state that iterators to end will be invalidated.
It needs to be amended in such a way as to account for end invalidation.
</p>
<p>
Something like:
</p>
<blockquote><p>
Any time the last element is erased, iterators to end are invalidated.
</p></blockquote>

<p>
This would handle situations like:
</p>
<blockquote><pre>erase(begin(), end())
erase(end() - 1)
pop_back()
resize(n, ...) where n &lt; size()
pop_front() with size() == 1

</pre></blockquote>



<p><b>Proposed resolution:</b></p>
<p>
Change 23.2.2.3 [deque.modifiers], p4:
</p>

<blockquote>
<pre>iterator erase(const_iterator position); 
iterator erase(const_iterator first, const_iterator last);
</pre>

<blockquote>
<p>
-4- <i>Effects:</i> An erase in the middle of the <tt>deque</tt>
invalidates all the iterators and references to elements of the
<tt>deque</tt> <ins>and the past-the-end iterator</ins>. An erase at
either end of the <tt>deque</tt> invalidates only the iterators and the
references to the erased elements<ins>, except that erasing at the end
also invalidates the past-the-end iterator</ins>.
</p>
</blockquote>
</blockquote>



<p><i>[
Kona (2007): Proposed wording added and moved to Review.
]</i></p>





<hr>
<h3><a name="645"></a>645. Missing members in match_results</h3>
<p><b>Section:</b> 28.10 [re.results] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-02-26</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#re.results">active issues</a> in [re.results].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#re.results">issues</a> in [re.results].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
According to the description given in 28.10 [re.results]/2 the class template
match_results "shall satisfy the requirements of a Sequence, [..],
except that only operations defined for const-qualified Sequences
are supported".
Comparing the provided operations from 28.10 [re.results]/3 with the
sequence/container tables 80 and 81 one recognizes the following
missing operations:
</p>

<p>
1) The members
</p>

<blockquote><pre>const_iterator rbegin() const;
const_iterator rend() const;
</pre></blockquote>

<p>
should exists because 23.1/10 demands these for containers
(all sequences are containers) which support bidirectional
iterators. Aren't these supported by match_result? This is not
explicitely expressed, but it's somewhat implied by two arguments:
</p>
<p>
(a) Several typedefs delegate to
<tt>iterator_traits&lt;BidirectionalIterator&gt;</tt>.
</p>
<p>
(b) The existence of <tt>const_reference operator[](size_type n) const</tt>
implies even random-access iteration.
I also suggest, that <tt>match_result</tt> should explicitly mention,
which minimum iterator category is supported and if this does
not include random-access the existence of <tt>operator[]</tt> is
somewhat questionable.
</p>
<p>
2) The new "convenience" members
</p>
<blockquote><pre>const_iterator cbegin() const;
const_iterator cend() const;
const_iterator crbegin() const;
const_iterator crend() const;
</pre></blockquote>
<p>
should be added according to tables 80/81.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add the following members to the <tt>match_results</tt> synopsis after <tt>end()</tt> in 28.10 [re.results]
para 3:
</p>

<blockquote><pre>const_iterator cbegin() const; 
const_iterator cend() const;
</pre></blockquote>

<p>
In section 28.10.3 [re.results.acc] change:
</p>

<blockquote>
<pre>const_iterator begin() const;
<ins>const_iterator cbegin() const;</ins>
</pre>
<blockquote>
<p>
-7- <i>Returns:</i> A starting iterator that enumerates over all the sub-expressions stored in <tt>*this</tt>.
</p>
</blockquote>

<pre>const_iterator end() const;
<ins>const_iterator cend() const;</ins>
</pre>
<blockquote>
<p>
-8- <i>Returns:</i> A terminating iterator that enumerates over all the sub-expressions stored in <tt>*this</tt>.
</p>
</blockquote>
</blockquote>



<p><i>[
Kona (2007): Voted to adopt proposed wording in
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2409.pdf">N2409</a>
except removing the entry in the table container requirements.  Moved to Review.
]</i></p>





<hr>
<h3><a name="653"></a>653. Library reserved names</h3>
<p><b>Section:</b> 1.2 [intro.refs] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-03-08</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#intro.refs">issues</a> in [intro.refs].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
</p>
<blockquote>
<p>
1.2 [intro.refs] Normative references
</p>

<p>
The following standards contain provisions which, through reference in
this text, constitute provisions of this Interna- tional Standard. At
the time of publication, the editions indicated were valid. All
standards are subject to revision, and parties to agreements based on
this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards
indicated below. Members of IEC and ISO maintain registers of currently
valid International Standards.
</p>

<ul>
<li>Ecma International, ECMAScript Language Specification, Standard
Ecma-262, third edition, 1999.</li>
<li>ISO/IEC 2382 (all parts), Information technology - Vocabulary</li>
<li>ISO/IEC 9899:1990, Programming languages - C</li>
<li>ISO/IEC 9899/Amd.1:1995, Programming languages - C, AMENDMENT 1: C
Integrity</li>
<li>ISO/IEC 9899:1999, Programming languages - C</li>
<li>ISO/IEC 9899:1999/Cor.1:2001 Programming languages - C</li>
<li>ISO/IEC 9899:1999/Cor.2:2004 Programming languages - C</li>
<li>ISO/IEC 9945:2003, Information Technology-Portable Operating System
Interface (POSIX)</li>
<li>ISO/IEC 10646-1:1993 Information technology - Universal Multiple-Octet
Coded Character Set (UCS) - Part 1: Architecture and Basic Multilingual
Plane</li>
</ul>
</blockquote>

<p>
I'm not sure how many of those reserve naming patterns that might affect
us, but I am equally sure I don't own a copy of any of these to check!
</p>
<p>
The point is to list the reserved naming patterns, rather than the
individual names themselves - although we may want to list C keywords
that are valid identifiers in C++ but likely to cause trouble in shared
headers (e.g. restrict)
</p>

<p><i>[
Kona (2007): Recommend NAD.  No one has identified a specific defect, just the possibility of one.
]</i></p>


<p><i>[
Post-Kona: Alisdair request Open. A good example of the problem was a
discussion of the system error proposal, where it was pointed out an all-caps
identifier starting with a capital E conflicted with reserved macro names for
both Posix and C.  I had absolutely no idea of this rule, and suspect I was
not the only one in the room.<br>
<br>
Resolution will require someone with access to all the listed documents to
research their respective name reservation rules, or people with access to
specific documents add their rules to this issue until the list is complete.
]</i></p>




<p><b>Proposed resolution:</b></p>





<hr>
<h3><a name="659"></a>659. istreambuf_iterator should have an operator-&gt;()</h3>
<p><b>Section:</b> 24.5.3 [istreambuf.iterator] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Niels Dekker <b>Date:</b> 2007-03-25</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#istreambuf.iterator">issues</a> in [istreambuf.iterator].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Greg Herlihy has clearly demonstrated that a user defined input
iterator should have an operator-&gt;(), even if its
value type is a built-in type (comp.std.c++, "Re: Should any iterator
have an operator-&gt;() in C++0x?", March 2007). &nbsp;And as Howard
Hinnant remarked in the same thread that the input iterator
<tt>istreambuf_iterator</tt> doesn't have one, this must be a
defect!
</p>
<p>
Based on Greg's example, the following code demonstrates the issue:
</p><pre>&nbsp;#include &lt;iostream&gt; 
&nbsp;#include &lt;fstream&gt;
&nbsp;#include &lt;streambuf&gt; 

&nbsp;typedef char C;
&nbsp;int main ()
&nbsp;{
&nbsp;&nbsp;&nbsp;std::ifstream s("filename", std::ios::in);
&nbsp;&nbsp;&nbsp;std::istreambuf_iterator&lt;char&gt; i(s);

&nbsp;&nbsp;&nbsp;(*i).~C(); &nbsp;// This is well-formed...
&nbsp;&nbsp;&nbsp;i-&gt;~C(); &nbsp;// ... so this should be supported!
&nbsp;}
</pre>

<p>
Of course, operator-&gt; is also needed when the value_type of
istreambuf_iterator is a class.
</p>
<p>
The operator-&gt; could be implemented in various ways. &nbsp;For instance,
by storing the current value inside the iterator, and returning its
address. &nbsp;Or by returning a proxy, like operator_arrow_proxy, from
<a href="http://www.boost.org/boost/iterator/iterator_facade.hpp">http://www.boost.org/boost/iterator/iterator_facade.hpp</a>
</p>
<p>
I hope that the resolution of this issue will contribute to getting a
clear and consistent definition of iterator concepts.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add to the synopsis in 24.5.3 [istreambuf.iterator]:
</p>

<blockquote><pre>charT operator*() const;
<ins>pointer operator-&gt;() const;</ins>
istreambuf_iterator&lt;charT,traits&gt;&amp; operator++();
</pre></blockquote>

<p>
Change 24.5.3 [istreambuf.iterator], p1:
</p>

<blockquote><p>
The class template <tt>istreambuf_iterator</tt> reads successive
characters from the <tt>streambuf</tt> for which it was constructed.
<tt>operator*</tt> provides access to the current input character, if
any. <ins><tt>operator-&gt;</tt> may return a proxy.</ins> Each time
<tt>operator++</tt> is evaluated, the iterator advances to the next
input character. If the end of stream is reached
(<tt>streambuf_type::sgetc()</tt> returns <tt>traits::eof()</tt>), the
iterator becomes equal to the end of stream iterator value. The default
constructor <tt>istreambuf_iterator()</tt> and the constructor
<tt>istreambuf_iterator(0)</tt> both construct an end of stream iterator
object suitable for use as an end-of-range.
</p></blockquote>



<p><i>[
Kona (2007): The proposed resolution is inconsistent because the return
type of <tt>istreambuf_iterator::operator-&gt;()</tt> is specified to be <tt>pointer</tt>,
but the proposed text also states that "<tt>operator-&gt;</tt> may return a proxy."
]</i></p>


<p><i>[
Niels Dekker (mailed to Howard Hinnant):
]</i></p>

<blockquote>
<p>
The proposed resolution does
not seem inconsistent to me. <tt>istreambuf_iterator::operator-&gt;()</tt> should
have <tt>istreambuf_iterator::pointer</tt> as return type, and this return type
may in fact be a proxy.
</p>
<p>
AFAIK, the resolution of <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#445">445</a> ("<tt>iterator_traits::reference</tt>
unspecified for some iterator categories") implies that for any iterator
class <tt>Iter</tt>, the return type of <tt>operator-&gt;()</tt> is <tt>Iter::pointer</tt>, by
definition. &nbsp;I don't think <tt>Iter::pointer</tt> needs to be a raw pointer.
</p>
<p>
Still I wouldn't mind if the text "<tt>operator-&gt;</tt> may return a proxy" would
be removed from the resolution. I think it's up to the library
implementation, how to implement <tt>istreambuf_iterator::operator-&gt;()</tt>. &nbsp;As
longs as it behaves as expected: <tt>i-&gt;m</tt> should have the same effect as
<tt>(*i).m</tt>. Even for an explicit destructor call, <tt>i-&gt;~C()</tt>. &nbsp;The main issue
is just: <tt>istreambuf_iterator</tt> should have an <tt>operator-&gt;()</tt>!
</p>
</blockquote>




<hr>
<h3><a name="661"></a>661. New 27.6.1.2.2 changes make special extractions useless</h3>
<p><b>Section:</b> 27.6.1.2.2 [istream.formatted.arithmetic] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-04-01</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#istream.formatted.arithmetic">active issues</a> in [istream.formatted.arithmetic].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#istream.formatted.arithmetic">issues</a> in [istream.formatted.arithmetic].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
To the more drastic changes of 27.6.1.2.2 [istream.formatted.arithmetic] in the current draft N2134 belong
the explicit description of the extraction of the types short and int in
terms of as-if code fragments.
</p>

<ol>
<li>
The corresponding as-if extractions in paragraph 2 and 3 will never
result in a change of the operator&gt;&gt; argument val, because the
contents of the local variable lval is in no case written into val.
Furtheron both fragments need a currently missing parentheses in the
beginning of the if-statement to be valid C++.
</li>
<li>I would like to ask whether the omission of a similar explicit
extraction of unsigned short and unsigned int in terms of long -
compared to their corresponding new insertions, as described in
27.6.2.6.2 [ostream.inserters.arithmetic], is a deliberate decision or
an
oversight.
</li>
</ol>


<p><b>Proposed resolution:</b></p>
<ol>
<li>
<p>
In 27.6.1.2.2 [istream.formatted.arithmetic]/2 change the current as-if code fragment
</p>
<blockquote><pre>typedef num_get&lt;charT,istreambuf_iterator&lt;charT,traits&gt; &gt; numget;
iostate err = 0;
long lval;
use_facet&lt;numget&gt;(loc).get(*this, 0, *this, err, lval );
if (err == 0) <ins>{</ins>
  <del>&amp;&amp;</del> <ins>if</ins> (lval &lt; numeric_limits&lt;short&gt;::min() || numeric_limits&lt;short&gt;::max() &lt; lval)<del>)</del>
      err = ios_base::failbit;
  <ins>else
    val = static_cast&lt;short&gt;(lval);
}</ins>
setstate(err);
</pre></blockquote>

<p>
Similarily in 27.6.1.2.2 [istream.formatted.arithmetic]/3 change the current as-if fragment
</p>

<blockquote><pre>typedef num_get&lt;charT,istreambuf_iterator&lt;charT,traits&gt; &gt; numget;
iostate err = 0;
long lval;
use_facet&lt;numget&gt;(loc).get(*this, 0, *this, err, lval );
if (err == 0) <ins>{</ins>
  <del>&amp;&amp;</del> <ins>if</ins> (lval &lt; numeric_limits&lt;int&gt;::min() || numeric_limits&lt;int&gt;::max() &lt; lval)<del>)</del>
      err = ios_base::failbit;
  <ins>else
    val = static_cast&lt;int&gt;(lval);
}</ins>
setstate(err);
</pre></blockquote>
</li>
<li>
---
</li>
</ol>


<p><i>[
Kona (2007): Note to the editor: the name lval in the call to <tt>use_facet</tt>
is incorrectly italicized in the code fragments corresponding to
<tt>operator&gt;&gt;(short &amp;)</tt> and <tt>operator &gt;&gt;(int &amp;)</tt>. Also, val -- which appears
twice on the line with the <tt>static_cast</tt> in the proposed resolution --
should be italicized. Also, in response to part two of the issue: this
is deliberate.
]</i></p>





<hr>
<h3><a name="664"></a>664. <tt>do_unshift</tt> for <tt>codecvt&lt;char, char, mbstate_t&gt;</tt></h3>
<p><b>Section:</b> 22.2.1.4.2 [locale.codecvt.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.codecvt.virtuals">active issues</a> in [locale.codecvt.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.codecvt.virtuals">issues</a> in [locale.codecvt.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.1.4.2 [locale.codecvt.virtuals], para 7 says (regarding <tt>do_unshift</tt>):
</p>

<blockquote><p>
<i>Effects:</i> Places characters starting at to that should be appended to
terminate a sequence when the current <tt>stateT</tt> is given by
<tt><i>state</i></tt>.<sup>237)</sup> Stores no more than <tt>(<i>to_limit</i> -
<i>to</i>)</tt> destination elements, and leaves the <tt><i>to_next</i></tt>
pointer pointing one beyond the last element successfully stored.
<em><tt>codecvt&lt;char, char, mbstate_t&gt;</tt> stores no characters.</em>
</p></blockquote>

<p>
The following objection has been raised:
</p>

<blockquote><p>
Since the C++ Standard permits a nontrivial conversion for the required
instantiations of <tt>codecvt</tt>, it is overly restrictive to say that
<tt>do_unshift</tt> must store no characters and return <tt>noconv</tt>.
</p></blockquote>

<p>
[Plum ref _222152Y50]
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 22.2.1.4.2 [locale.codecvt.virtuals], p7:
</p>

<blockquote>
<p>
<i>Effects:</i> Places characters starting at <i>to</i> that should be
appended to terminate a sequence when the current <tt>stateT</tt> is
given by state.<sup>237)</sup> Stores no more than (<i>to_limit -to</i>)
destination elements, and leaves the <i>to_next</i> pointer pointing one
beyond the last element successfully stored. <del><tt>codecvt&lt;char, char,
mbstate_t&gt;</tt> stores no characters.</del>
</p>
</blockquote>





<hr>
<h3><a name="665"></a>665. <tt>do_unshift</tt> return value</h3>
<p><b>Section:</b> 22.2.1.4.2 [locale.codecvt.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.codecvt.virtuals">active issues</a> in [locale.codecvt.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.codecvt.virtuals">issues</a> in [locale.codecvt.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.1.4.2 [locale.codecvt.virtuals], para 8 says:
</p>

<blockquote><p>
<tt>codecvt&lt;char,char,mbstate_t&gt;</tt>, returns <tt>noconv</tt>.
</p></blockquote>

<p>
The following objection has been raised:
</p>

<blockquote><p>
Despite what the C++ Standard&nbsp;
says, <tt>unshift</tt> can't always return <tt>noconv</tt> for the default facets, since&nbsp;
they can be nontrivial. At least one implementation does whatever the&nbsp;
C functions do.
</p></blockquote>

<p>
[Plum ref _222152Y62]
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 22.2.1.4.2 [locale.codecvt.virtuals], p8:
</p>

<blockquote>
<p><i>Returns:</i> An enumeration value, as summarized in Table 76:</p>
<p>...</p>
<p>
<del><tt>codecvt&lt;char,char,mbstate_t&gt;</tt>, returns <tt>noconv</tt>.</del>
</p>
</blockquote>






<hr>
<h3><a name="666"></a>666. <tt>moneypunct::do_curr_symbol()</tt></h3>
<p><b>Section:</b> 22.2.6.3.2 [locale.moneypunct.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.moneypunct.virtuals">issues</a> in [locale.moneypunct.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.6.3.2 [locale.moneypunct.virtuals], para 4 footnote 257 says
</p>

<blockquote><p>
<sup>257)</sup> For international&nbsp;
specializations (second template parameter <tt>true</tt>) this is always four&nbsp;
characters long, usually three letters and a space.
</p></blockquote>

<p>
The following objection has been raised:
</p>

<blockquote><p>
The international currency&nbsp;
symbol is whatever the underlying locale says it is, not necessarily&nbsp;
four characters long.
</p></blockquote>

<p>
[Plum ref _222632Y41]
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change footnote 253 in 22.2.6.3.2 [locale.moneypunct.virtuals]:
</p>

<blockquote>
<p>
<sup>253)</sup> For international specializations (second template
parameter <tt>true</tt>) this is <del>always</del> <ins>typically</ins>
four characters long, usually three letters and a space.
</p>
</blockquote>





<hr>
<h3><a name="667"></a>667. <tt>money_get</tt>'s widened minus sign</h3>
<p><b>Section:</b> 22.2.6.1.2 [locale.money.get.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.money.get.virtuals">active issues</a> in [locale.money.get.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.money.get.virtuals">issues</a> in [locale.money.get.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.6.1.2 [locale.money.get.virtuals], para 1 says:
</p>

<blockquote><p>
The result is returned as an integral value&nbsp;
stored in <tt>units</tt> or as a sequence of digits possibly preceded by a&nbsp;
minus sign (as produced by <tt>ct.widen(c)</tt> where <tt>c</tt> is '-' or in the range&nbsp;
from '0' through '9', inclusive) stored in <tt>digits</tt>.
</p></blockquote>

<p>
The following
objection has been raised:
</p>

<blockquote><p>
Some implementations interpret this to mean that a facet derived from
<tt>ctype&lt;wchar_t&gt;</tt> can provide its own member <tt>do_widen(char)</tt>
which produces e.g. <tt>L'@'</tt> for the "widened" minus sign, and that the
<tt>'@'</tt> symbol will appear in the resulting sequence of digits.&nbsp; Other
implementations have assumed that one or more places in the standard permit the
implementation to "hard-wire" <tt>L'-'</tt> as the "widened" minus sign.&nbsp; Are
both interpretations permissible, or only&nbsp; one?
</p></blockquote>

<p>
[Plum ref _222612Y14]
</p>

<p>
Furthermore: if <tt>ct.widen('9')</tt> produces <tt>L'X'</tt> (a non-digit), does a
parse fail if a <tt>'9'</tt> appears in the subject string? [Plum ref _22263Y33]
</p>

<p><i>[
Kona (2007): Bill and Dietmar to provide proposed wording.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="668"></a>668. <tt>money_get</tt>'s empty minus sign</h3>
<p><b>Section:</b> 22.2.6.1.2 [locale.money.get.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.money.get.virtuals">active issues</a> in [locale.money.get.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.money.get.virtuals">issues</a> in [locale.money.get.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.6.1.2 [locale.money.get.virtuals], para 3 says:
</p>

<blockquote><p>
If <tt>pos</tt> or <tt>neg</tt> is empty, the sign component is
optional, and if no sign is detected, the result is given the sign&nbsp;
that corresponds to the source of the empty string.
</p></blockquote>

<p>
The following
objection has been raised:
</p>

<blockquote><p>
A <tt>negative_sign</tt> of "" means "there is no&nbsp;
way to write a negative sign" not "any null sequence is a negative&nbsp;
sign, so it's always there when you look for it".
</p></blockquote>

<p>
[Plum ref _222612Y32]
</p>

<p><i>[
Kona (2007): Bill to provide proposed wording and interpretation of existing wording.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="669"></a>669. Equivalent postive and negative signs in <tt>money_get</tt></h3>
<p><b>Section:</b> 22.2.6.1.2 [locale.money.get.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#locale.money.get.virtuals">active issues</a> in [locale.money.get.virtuals].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#locale.money.get.virtuals">issues</a> in [locale.money.get.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.6.1.2 [locale.money.get.virtuals], para 3 sentence 4 says:
</p>

<blockquote><p>
If the first character of <tt>pos</tt> is equal to the first character of <tt>neg</tt>,&nbsp;
or if both strings are empty, the result is given a positive sign.
</p></blockquote>

<p>
One interpretation is that an input sequence must match either the
positive pattern or the negative pattern, and then in either event it
is interpreted as positive.&nbsp; The following objections has been raised:
</p>

<blockquote><p>
The input can successfully match only a positive sign, so the negative
pattern is an unsuccessful match.
</p></blockquote>

<p>
[Plum ref _222612Y34, 222612Y51b]
</p>

<p><i>[
Bill to provide proposed wording and interpretation of existing wording.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="670"></a>670. <tt>money_base::pattern</tt> and <tt>space</tt></h3>
<p><b>Section:</b> 22.2.6.3 [locale.moneypunct] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Thomas Plum <b>Date:</b> 2007-04-16</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
22.2.6.3 [locale.moneypunct], para 2 says:
</p>

<blockquote><p>
The value <tt>space</tt> indicates that at least one space is required at&nbsp;
that position.
</p></blockquote>

<p>
The following objection has been raised:
</p>

<blockquote><p>
Whitespace&nbsp;is optional when matching space. (See 22.2.6.1.2 [locale.money.get.virtuals], para 2.)
</p></blockquote>

<p>
[Plum ref _22263Y22]
</p>

<p><i>[
Kona (2007): Bill to provide proposed wording. We agree that C++03 is
ambiguous, and that we want C++0X to say "space" means 0 or more
whitespace characters on input.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="671"></a>671. precision of hexfloat</h3>
<p><b>Section:</b> 22.2.2.2.2 [facet.num.put.virtuals] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> John Salmon <b>Date:</b> 2007-04-20</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#facet.num.put.virtuals">issues</a> in [facet.num.put.virtuals].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I am trying to understand how TR1 supports hex float (%a) output.
</p>
<p>
As far as I can tell, it does so via the following:
</p>
<p>
8.15 Additions to header &lt;locale&gt; [tr.c99.locale]
</p>
<p>
In subclause 22.2.2.2.2 [facet.num.put.virtuals], Table 58 Floating-point conversions, after
the line:
floatfield == ios_base::scientific %E
</p>
<p>
add the two lines:
</p>
<blockquote><pre>floatfield == ios_base::fixed | ios_base::scientific &amp;&amp; !uppercase %a
floatfield == ios_base::fixed | ios_base::scientific %A 2
</pre></blockquote>
<p>
[Note: The additional requirements on print and scan functions, later
in this clause, ensure that the print functions generate hexadecimal
floating-point fields with a %a or %A conversion specifier, and that
the scan functions match hexadecimal floating-point fields with a %g
conversion specifier. &nbsp;end note]
</p>
<p>
Following the thread, in 22.2.2.2.2 [facet.num.put.virtuals], we find:
</p>
<p>
For conversion from a floating-point type, if (flags &amp; fixed) != 0 or
if str.precision() &gt; 0, then str.precision() is specified in the
conversion specification.
</p>
<p>
This would seem to imply that when floatfield == fixed|scientific, the
precision of the conversion specifier is to be taken from
str.precision(). &nbsp;Is this really what's intended? &nbsp;I sincerely hope
that I'm either missing something or this is an oversight. &nbsp;Please
tell me that the committee did not intend to mandate that hex floats
(and doubles) should by default be printed as if by %.6a.
</p>

<p><i>[
Howard: I think the fundamental issue we overlooked was that with %f,
%e, %g, the default precision was always 6. &nbsp;With %a the default
precision is not 6, it is infinity. &nbsp;So for the first time, we need to
distinguish between the default value of precision, and the precision
value 6.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
</p>


<p><i>[
Kona (2007): Robert volunteers to propose wording.
]</i></p>





<hr>
<h3><a name="672"></a>672. Swappable requirements need updating</h3>
<p><b>Section:</b> 20.1.1 [utility.arg.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-05-04</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#utility.arg.requirements">active issues</a> in [utility.arg.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#utility.arg.requirements">issues</a> in [utility.arg.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The current <tt>Swappable</tt> is:
</p>

<blockquote>
<table border="1">
<caption>Table 37: <tt>Swappable</tt> requirements <b>[swappable]</b></caption>
<tbody><tr><th>expression</th><th>return type</th><th>post-condition</th></tr>
<tr><td><tt>swap(s,t)</tt></td><td><tt>void</tt></td><td><tt>t</tt> has the value originally held by <tt>u</tt>, and <tt>u</tt> has the value originally 
held by <tt>t</tt></td></tr>
<tr><td colspan="3">
<p>
The Swappable requirement is met by satisfying one or more of the following conditions:
</p>
<ul>
<li>
<tt>T</tt> is Swappable if <tt>T</tt> satisfies the <tt>CopyConstructible</tt> requirements (Table 34) 
and the <tt>CopyAssignable</tt> requirements (Table 36);
</li>
<li>
<tt>T</tt> is Swappable if a namespace scope function named <tt>swap</tt> exists in the same 
namespace as the definition of <tt>T</tt>, such that the expression <tt>swap(t,u)</tt> is valid 
and has the semantics described in this table.
</li>
</ul>
</td></tr>
</tbody></table>
</blockquote>

<p>
With the passage of rvalue reference into the language, <tt>Swappable</tt> needs to be updated to
require only <tt>MoveConstructible</tt> and <tt>MoveAssignable</tt>.  This is a minimum.
</p>

<p>
Additionally we may want to support proxy references such that the following code is acceptable:
</p>

<blockquote><pre>namespace Mine {

template &lt;class T&gt;
struct proxy {...};

template &lt;class T&gt;
struct proxied_iterator
{
   typedef T value_type;
   typedef proxy&lt;T&gt; reference;
   reference operator*() const;
   ...
};

struct A
{
   // heavy type, has an optimized swap, maybe isn't even copyable or movable, just swappable
   void swap(A&amp;);
   ...
};

void swap(A&amp;, A&amp;);
void swap(proxy&lt;A&gt;, A&amp;);
void swap(A&amp;, proxy&lt;A&gt;);
void swap(proxy&lt;A&gt;, proxy&lt;A&gt;);

}  // Mine

...

Mine::proxied_iterator&lt;Mine::A&gt; i(...)
Mine::A a;
swap(*i1, a);
</pre></blockquote>

<p>
I.e. here is a call to <tt>swap</tt> which the user enables swapping between a proxy to a class and the class
itself.  We do not need to anything in terms of implementation except not block their way with overly
constrained concepts.  That is, the <tt>Swappable</tt> concept should be expanded to allow swapping
between two different types for the case that one is binding to a user-defined <tt>swap</tt>.
</p>



<p><b>Proposed resolution:</b></p>

<p>
Change 20.1.1 [utility.arg.requirements]:
</p>

<blockquote>

<p>
-1- The template definitions in the C++ Standard Library refer to various
named requirements whose details are set out in tables 31-38. In these
tables, <tt>T</tt> is a type to be supplied by a C++ program
instantiating a template; <tt>a</tt>, <tt>b</tt>, and <tt>c</tt> are
values of type <tt>const T</tt>; <tt>s</tt> and <tt>t</tt> are modifiable
lvalues of type <tt>T</tt>; <tt>u</tt> is a value of type (possibly
<tt>const</tt>) <tt>T</tt>; and <tt>rv</tt> is a non-<tt>const</tt>
rvalue of type <tt>T</tt>.
</p>

<table border="1">
<caption>Table 37: <tt>Swappable</tt> requirements <b>[swappable]</b></caption>
<tbody><tr><th>expression</th><th>return type</th><th>post-condition</th></tr>
<tr><td><tt>swap(s,t)</tt></td><td><tt>void</tt></td>
<td><tt>t</tt> has the value originally
held by <tt>u</tt>, and
<tt>u</tt> has the value originally held
by <tt>t</tt></td></tr>
<tr><td colspan="3">
<p>
The <tt>Swappable</tt> requirement is met by satisfying one or more of the following conditions:
</p>
<ul>
<li>
<tt>T</tt> is <tt>Swappable</tt> if <tt>T</tt> satisfies the
<del><tt>CopyConstructible</tt></del> <ins>MoveConstructible</ins>
requirements (Table <del>34</del> <ins>33</ins>) and the <del><tt>CopyAssignable</tt></del> <ins>MoveAssignable</ins>
requirements (Table <del>36</del> <ins>35</ins>);
</li>
<li>
<tt>T</tt> is <tt>Swappable</tt> if a namespace scope function named
<tt>swap</tt> exists in the same namespace as the definition of
<tt>T</tt>, such that the expression
<tt>swap(t,u)</tt> is valid and has the
semantics described in this table.
</li>
</ul>
</td></tr>
</tbody></table>
</blockquote>



<p><i>[
Kona (2007): We like the change to the <tt>Swappable</tt> requirements to use
move semantics. The issue relating to the support of proxies is
separable from the one relating to move semantics, and it's bigger than
just swap. We'd like to address only the move semantics changes under
this issue, and open a separated issue (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#742">742</a>) to handle proxies. Also, there
may be a third issue, in that the current definition of <tt>Swappable</tt> does
not permit rvalues to be operands to a swap operation, and Howard's
proposed resolution would allow the right-most operand to be an rvalue,
but it would not allow the left-most operand to be an rvalue (some swap
functions in the library have been overloaded to permit left operands to
swap to be rvalues).
]</i></p>





<hr>
<h3><a name="673"></a>673. <tt>unique_ptr</tt> update</h3>
<p><b>Section:</b> 20.6.5 [unique.ptr] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-05-04</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Since the publication of
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1856.html">N1856</a>
there have been a few small but significant advances which should be included into
<tt>unique_ptr</tt>.  There exists a
<a href="http://home.twcny.rr.com/hinnant/cpp_extensions/unique_ptr.html">reference implmenation</a>
for all of these changes.
</p>

<ul>

<li>
<p>
Even though <tt>unique_ptr&lt;void&gt;</tt> is not a valid use case (unlike for <tt>shared_ptr&lt;void&gt;</tt>),
unexpected cases to crop up which require the instantiation of the interface of <tt>unique_ptr&lt;void&gt;</tt>
even if it is never used.  For example see
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#541">LWG 541</a> for how this accidently
happened to <tt>auto_ptr</tt>.  I believe the most robust way to protect <tt>unique_ptr</tt> against this
type of failure is to augment the return type of <tt>unique_ptr&lt;T&gt;:operator*()</tt> with
<tt>add_lvalue_reference&lt;T&gt;::type</tt>.  This means that given an instantiated <tt>unique_ptr&lt;void&gt;</tt>
the act of dereferencing it will simply return <tt>void</tt> instead of causing a compile time failure.
This is simpler than creating a <tt>unique_ptr&lt;void&gt;</tt> specialization which isn't robust in the
face of <tt><i>cv-</i></tt>qualified <tt>void</tt> types.
</p>

<p>
This resolution also supports instantiations such as <tt>unique_ptr&lt;void, free_deleter&gt;</tt>
which could be very useful to the client.
</p>

</li>

<li>
<p>
Efforts have been made to better support containers and smart pointers in shared
memory contexts.  One of the key hurdles in such support is not assuming that a
pointer type is actually a <tt>T*</tt>.  This can easily be accomplished
for <tt>unique_ptr</tt> by having the deleter define the pointer type:
<tt>D::pointer</tt>.  Furthermore this type can easily be defaulted to
<tt>T*</tt> should the deleter <tt>D</tt> choose not to define a pointer
type (reference implementation
<a href="http://home.twcny.rr.com/hinnant/cpp_extensions/unique_ptr.html">here</a>).
This change has no run time overhead.  It has no interface overhead on
authors of custom delter types.  It simply allows (but not requires)
authors of custom deleter types to define a smart pointer for the
storage type of <tt>unique_ptr</tt> if they find such functionality
useful.  <tt>std::default_delete</tt> is an example of a deleter which
defaults <tt>pointer</tt> to <tt>T*</tt> by simply ignoring this issue
and not including a <tt>pointer typedef</tt>.
</p>
</li>

<li>
<p>
When the deleter type is a function pointer then it is unsafe to construct
a <tt>unique_ptr</tt> without specifying the function pointer in the constructor.
This case is easy to check for with a <tt>static_assert</tt> assuring that the
deleter is not a pointer type in those constructors which do not accept deleters.
</p>

<blockquote><pre>unique_ptr&lt;A, void(*)(void*)&gt; p(new A);  // error, no function given to delete the pointer!
</pre></blockquote>

</li>

</ul>

<p><i>[
Kona (2007): We don't like the solution given to the first bullet in
light of concepts. The second bullet solves the problem of supporting
fancy pointers for one library component only. The full LWG needs to
decide whether to solve the problem of supporting fancy pointers
piecemeal, or whether a paper addressing the whole library is needed. We
think that the third bullet is correct.
]</i></p>


<p><i>[
Post Kona: Howard adds example user code related to the first bullet:
]</i></p>


<blockquote>
<pre>void legacy_code(void*, std::size_t);

void foo(std::size_t N)
{
    std::unique_ptr&lt;void, void(*)(void*)&gt; ptr(std::malloc(N), std::free);
    legacy_code(ptr.get(), N);
}   // unique_ptr used for exception safety purposes
</pre>
</blockquote>

<p>
I.e. <tt>unique_ptr&lt;void&gt;</tt> <i>is</i> a useful tool that we don't want
to disable with concepts.  The only part of <tt>unique_ptr&lt;void&gt;</tt> we
want to disable (with concepts or by other means) are the two member functions:
</p>

<blockquote><pre>T&amp; operator*() const;
T* operator-&gt;() const;
</pre></blockquote>



<p><b>Proposed resolution:</b></p>

<p><i>[
I am grateful for the generous aid of Peter Dimov and Ion Gaztañaga in helping formulate and review
the proposed resolutions below.
]</i></p>


<ul>
<li>

<p>
Change 20.6.5.2 [unique.ptr.single]:
</p>

<blockquote><pre>template &lt;class T, class D = default_delete&lt;T&gt;&gt; class unique_ptr {
   ...
   <del>T&amp;</del> <ins>typename add_lvalue_reference&lt;T&gt;::type</ins> operator*() const;
   ...
};
</pre></blockquote>

<p>
Change 20.6.5.2.4 [unique.ptr.single.observers]:
</p>

<blockquote><pre><del>T&amp;</del> <ins>typename add_lvalue_reference&lt;T&gt;::type</ins> operator*() const;
</pre></blockquote>

</li>

<li>
<p>
Change 20.6.5.2 [unique.ptr.single]:
</p>

<blockquote><pre>template &lt;class T, class D = default_delete&lt;T&gt;&gt; class unique_ptr {
public:
  <ins>typedef <i>implementation (see description below)</i> pointer;</ins>
   ...
   explicit unique_ptr(<del>T*</del> <ins>pointer</ins> p);
   ...
   unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined (see description below)</i> d);
   unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined (see description below)</i> d);
   ...
   <del>T*</del> <ins>pointer</ins> operator-&gt;() const;
   <del>T*</del> <ins>pointer</ins> get() const;
   ...
   <del>T*</del> <ins>pointer</ins> release();
   void reset(<del>T*</del> <ins>pointer</ins> p = <del>0</del> <ins>pointer()</ins>);
};
</pre></blockquote>

<p>
<ins>
-3- If the type <tt>remove_reference&lt;D&gt;::type::pointer</tt>
exists, then <tt>unique_ptr&lt;T, D&gt;::pointer</tt> is a typedef to
<tt>remove_reference&lt;D&gt;::type::pointer</tt>.  Otherwise
<tt>unique_ptr&lt;T, D&gt;::pointer</tt> is a typedef to <tt>T*</tt>.
The type <tt>unique_ptr&lt;T, D&gt;::pointer</tt> must be <tt>CopyConstructible</tt>
and <tt>CopyAssignable</tt>.
</ins>
</p>

<p>
Change 20.6.5.2.1 [unique.ptr.single.ctor]:
</p>

<blockquote><pre>unique_ptr(<del>T*</del> <ins>pointer</ins> p);
...
unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d); 
unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d); 
...
unique_ptr(<del>T*</del> <ins>pointer</ins> p, const A&amp; d);
unique_ptr(<del>T*</del> <ins>pointer</ins> p, A&amp;&amp; d);
...
unique_ptr(<del>T*</del> <ins>pointer</ins> p, A&amp; d); 
unique_ptr(<del>T*</del> <ins>pointer</ins> p, A&amp;&amp; d);
...
unique_ptr(<del>T*</del> <ins>pointer</ins> p, const A&amp; d); 
unique_ptr(<del>T*</del> <ins>pointer</ins> p, const A&amp;&amp; d);
...
</pre></blockquote>

<p>
-23- <i>Requires:</i> If <tt>D</tt> is not a reference type,
construction of the deleter <tt>D</tt> from an rvalue of type <tt>E</tt>
must be well formed and not throw an exception. If <tt>D</tt> is a
reference type, then <tt>E</tt> must be the same type as <tt>D</tt>
(diagnostic required). <del><tt>U*</tt></del> <ins><tt>unique_ptr&lt;U,E&gt;::pointer</tt></ins>
must be implicitly convertible to <del><tt>T*</tt></del>
<ins>pointer</ins>.
</p>

<p>
-25- <i>Postconditions:</i> <tt>get() == value u.get()</tt> had before
the construction, modulo any required offset adjustments resulting from
the cast from <del><tt>U*</tt></del>
<ins><tt>unique_ptr&lt;U,E&gt;::pointer</tt></ins> to <del><tt>T*</tt></del>
<ins>pointer</ins>. <tt>get_deleter()</tt> returns a reference to the
internally stored deleter which was constructed from
<tt>u.get_deleter()</tt>.
</p>

<p>
Change 20.6.5.2.3 [unique.ptr.single.asgn]:
</p>

<blockquote>
<p>
-8- <i>Requires:</i> Assignment of the deleter <tt>D</tt> from an rvalue
<tt>D</tt> must not throw an exception. <del><tt>U*</tt></del>
<ins><tt>unique_ptr&lt;U,E&gt;::pointer</tt></ins> must be implicitly
convertible to <del><tt>T*</tt></del> <ins>pointer</ins>.
</p>
</blockquote>

<p>
Change 20.6.5.2.4 [unique.ptr.single.observers]:
</p>

<blockquote>
<pre><del>T*</del> <ins>pointer</ins> operator-&gt;() const;</pre>
...
<pre><del>T*</del> <ins>pointer</ins> get() const;</pre>
</blockquote>

<p>
Change 20.6.5.2.5 [unique.ptr.single.modifiers]:
</p>

<blockquote>
<pre><del>T*</del> <ins>pointer</ins> release();</pre>
...
<pre>void reset(<del>T*</del> <ins>pointer</ins> p = <del>0</del> <ins>pointer()</ins>);</pre>
</blockquote>

<p>
Change 20.6.5.3 [unique.ptr.runtime]:
</p>

<blockquote><pre>template &lt;class T, class D&gt; class unique_ptr&lt;T[], D&gt; {
public:
  <ins>typedef <i>implementation</i> pointer;</ins>
   ...
   explicit unique_ptr(<del>T*</del> <ins>pointer</ins> p);
   ...
   unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d);
   unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d);
   ...
   <del>T*</del> <ins>pointer</ins> get() const;
   ...
   <del>T*</del> <ins>pointer</ins> release();
   void reset(<del>T*</del> <ins>pointer</ins> p = <del>0</del> <ins>pointer()</ins>);
};
</pre></blockquote>

<p>
Change 20.6.5.3.1 [unique.ptr.runtime.ctor]:
</p>

<blockquote>
<pre>unique_ptr(<del>T*</del> <ins>pointer</ins> p);
unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d);
unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d);
</pre>

<p>
These constructors behave the same as in the primary template except
that they do not accept pointer types which are convertible to
<del><tt>T*</tt></del> <ins><tt>pointer</tt></ins>. [<i>Note:</i> One
implementation technique is to create private templated overloads of
these members. <i>-- end note</i>]
</p>
</blockquote>

<p>
Change 20.6.5.3.3 [unique.ptr.runtime.modifiers]:
</p>

<blockquote>
<pre>void reset(<del>T*</del> <ins>pointer</ins> p = <del>0</del> <ins>pointer()</ins>);
</pre>

<p>
-1- <i>Requires:</i> Does not accept pointer types which are convertible
to <del><tt>T*</tt></del> <ins><tt>pointer</tt></ins> (diagnostic
required). [<i>Note:</i> One implementation technique is to create a private
templated overload. <i>-- end note</i>]
</p>
</blockquote>

<p>
Change 20.6.5.4 [unique.ptr.compiletime]:
</p>

<blockquote><pre>template &lt;class T, class D,  size_t N&gt; class unique_ptr&lt;T[N], D&gt; {
public:
  <ins>typedef <i>implementation</i> pointer;</ins>
   ...
   explicit unique_ptr(<del>T*</del> <ins>pointer</ins> p);
   ...
   unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d);
   unique_ptr(<del>T*</del> <ins>pointer</ins> p, <i>implementation defined</i> d);
   ...
   <del>T*</del> <ins>pointer</ins> get() const;
   ...
   <del>T*</del> <ins>pointer</ins> release();
   void reset(<del>T*</del> <ins>pointer</ins> p = <del>0</del> <ins>pointer()</ins>);
};
</pre></blockquote>

<p>
Change 20.6.5.4.3 [unique.ptr.compiletime.modifiers]:
</p>

<blockquote>
<pre>void reset(<del>T*</del> <ins>pointer</ins> p = <del>0</del> <ins>pointer()</ins>);
</pre>

<p>
-1- <i>Requires:</i> Does not accept pointer types which are convertible
to <del><tt>T*</tt></del> <ins><tt>pointer</tt></ins> (dignostic required). [<i>Note:</i> One implementation
technique is to create a private templated overload. <i>--end note</i>]
</p>

</blockquote>

</li>

<li>

<p>
Change 20.6.5.2.1 [unique.ptr.single.ctor]:
</p>

<blockquote>
<pre>unique_ptr();</pre>
<blockquote>
<p>
<i>Requires:</i> <tt>D</tt> must be default constructible, and that
construction must not throw an exception. <tt>D</tt> must not be a
reference type <ins>or pointer type (diagnostic required)</ins>.
</p>
</blockquote>
<pre>unique_ptr(<del>T*</del> <ins>pointer</ins> p);</pre>
<blockquote>
<p>
<i>Requires:</i>  The expression <tt>D()(p)</tt> must be well formed.
The default constructor of <tt>D</tt> must not throw an exception.
<tt>D</tt> must not be a reference type <ins>or pointer type (diagnostic
required)</ins>.
</p>
</blockquote>
</blockquote>

<p>
Change 20.6.5.2.1 [unique.ptr.single.ctor]:
</p>

<blockquote>
<pre>unique_ptr();</pre>
<blockquote>
<p>
<i>Requires:</i> <tt>D</tt> must be default constructible, and that
construction must not throw an exception. <tt>D</tt> must not be a
reference type <ins>or pointer type (diagnostic required)</ins>.
</p>
</blockquote>
<pre>unique_ptr(<del>T*</del> <ins>pointer</ins> p);</pre>
<blockquote>
<p>
<i>Requires:</i>  The expression <tt>D()(p)</tt> must be well formed.
The default constructor of <tt>D</tt> must not throw an exception.
<tt>D</tt> must not be a reference type <ins>or pointer type (diagnostic
required)</ins>.
</p>
</blockquote>
</blockquote>

</li>

</ul>






<hr>
<h3><a name="674"></a>674. <tt>shared_ptr</tt> interface changes for consistency with N1856</h3>
<p><b>Section:</b> 20.6.6.2 [util.smartptr.shared] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-05-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#util.smartptr.shared">active issues</a> in [util.smartptr.shared].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#util.smartptr.shared">issues</a> in [util.smartptr.shared].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1856.html">N1856</a> does not propose
any changes to <tt>shared_ptr</tt>. It needs to be updated to use a rvalue reference where appropriate
and to interoperate with <tt>unique_ptr</tt> as it does with <tt>auto_ptr</tt>.
</p>


<p><b>Proposed resolution:</b></p>

<p>
Change 20.6.6.2 [util.smartptr.shared] as follows:
</p>

<blockquote>
<pre>template&lt;class Y&gt; explicit shared_ptr(auto_ptr&lt;Y&gt;<del>&amp;</del><ins>&amp;&amp;</ins> r);
<ins>template&lt;class Y, class D&gt; explicit shared_ptr(const unique_ptr&lt;Y,D&gt;&amp; r) = delete;
template&lt;class Y, class D&gt; explicit shared_ptr(unique_ptr&lt;Y,D&gt;&amp;&amp; r);</ins>
...
template&lt;class Y&gt; shared_ptr&amp; operator=(auto_ptr&lt;Y&gt;<del>&amp;</del><ins>&amp;&amp;</ins> r);
<ins>template&lt;class Y, class D&gt; shared_ptr&amp; operator=(const unique_ptr&lt;Y,D&gt;&amp; r) = delete;
template&lt;class Y, class D&gt; shared_ptr&amp; operator=(unique_ptr&lt;Y,D&gt;&amp;&amp; r);</ins></pre>
</blockquote>

<p>
Change 20.6.6.2.1 [util.smartptr.shared.const] as follows:
</p>

<blockquote>
<pre><ins>template&lt;class Y&gt; shared_ptr(auto_ptr&lt;Y&gt;<del>&amp;</del><ins>&amp;&amp;</ins> r);</ins></pre>
</blockquote>

<p>
Add to 20.6.6.2.1 [util.smartptr.shared.const]:
</p>

<blockquote>
<pre><ins>template&lt;class Y, class D&gt; shared_ptr(unique_ptr&lt;Y, D&gt;&amp;&amp; r);</ins></pre>
<blockquote>

<p><ins>
<i>Effects:</i> Equivalent to <tt>shared_ptr( r.release(), r.get_deleter() )</tt> when <tt>D</tt> is
          not a reference type, <tt>shared_ptr( r.release(), ref( r.get_deleter() ) )</tt>
          otherwise.
</ins></p>

<p><ins>
<i>Exception safety:</i> If an exception is thrown, the constructor has no effect.
</ins></p>
</blockquote>

</blockquote>

<p>
Change 20.6.6.2.3 [util.smartptr.shared.assign] as follows:
</p>

<blockquote>
<pre>template&lt;class Y&gt; shared_ptr&amp; operator=(auto_ptr&lt;Y&gt;<del>&amp;</del><ins>&amp;&amp;</ins> r);</pre>
</blockquote>

<p>
Add to 20.6.6.2.3 [util.smartptr.shared.assign]:
</p>

<blockquote>
<pre><ins>template&lt;class Y, class D&gt; shared_ptr&amp; operator=(unique_ptr&lt;Y,D&gt;&amp;&amp; r);</ins></pre>

<blockquote>
<p><ins>
-4- <i>Effects:</i> Equivalent to <tt>shared_ptr(std::move(r)).swap(*this)</tt>.
</ins></p>
<p><ins>
-5- <i>Returns:</i> <tt>*this</tt>.
</ins></p>
</blockquote>

</blockquote>



<p><i>[
Kona (2007): We may need to open an issue (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#743">743</a>) to deal with the question of
whether <tt>shared_ptr</tt> needs an rvalue <tt>swap</tt>.
]</i></p>





<hr>
<h3><a name="675"></a>675. Move assignment of containers</h3>
<p><b>Section:</b> 23.1 [container.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-05-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#container.requirements">active issues</a> in [container.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#container.requirements">issues</a> in [container.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
James Hopkin pointed out to me that if <tt>vector&lt;T&gt;</tt> move assignment is O(1)
(just a <tt>swap</tt>) then containers such as <tt>vector&lt;shared_ptr&lt;ostream&gt;&gt;</tt> might have
the wrong semantics under move assignment when the source is not truly an rvalue, but a
moved-from lvalue (destructors could run late).
</p>

<blockquote><pre><tt>vector&lt;shared_ptr&lt;ostream&gt;&gt;</tt> v1;
<tt>vector&lt;shared_ptr&lt;ostream&gt;&gt;</tt> v2;
...
v1 = v2;               // #1
v1 = std::move(v2);    // #2
</pre></blockquote>

<p>
Move semantics means not caring what happens to the source (<tt>v2</tt> in this example).
It doesn't mean not caring what happens to the target (<tt>v1</tt>).  In the above example
both assignments should have the same effect on <tt>v1</tt>.  Any non-shared <tt>ostream</tt>'s
<tt>v1</tt> owns before the assignment should be closed, whether <tt>v1</tt> is undergoing
copy assignment or move assignment.
</p>

<p>
This implies that the semantics of move assignment of a generic container should be
<tt>clear, swap</tt> instead of just swap.  An alternative which could achieve the same
effect would be to move assign each element.  In either case, the complexity of move
assignment needs to be relaxed to <tt>O(v1.size())</tt>.
</p>

<p>
The performance hit of this change is not nearly as drastic as it sounds. 
In practice, the target of a move assignment has always just been move constructed
or move assigned <i>from</i>.  Therefore under <tt>clear, swap</tt> semantics (in
this common use case) we are still achieving O(1) complexity.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change 23.1 [container.requirements]:
</p>

<blockquote>
<table border="1">
<caption>Table 86: Container requirements</caption>
<tbody><tr>
<th>expression</th><th>return type</th><th>operational semantics</th>
<th>assertion/note pre/post-condition</th><th>complexity</th>
</tr>
<tr>
<td><tt>a = rv;</tt></td><td><tt>X&amp;</tt></td>
<td><ins>All existing elements of <tt>a</tt> are either move assigned or destructed</ins></td>
<td><tt>a</tt> shall be equal to the 
value that <tt>rv</tt> had 
before this construction
</td>
<td><del>constant</del> <ins>linear in <tt>a.size()</tt></ins></td>
</tr>
</tbody></table>
</blockquote>






<hr>
<h3><a name="676"></a>676. Moving the unordered containers</h3>
<p><b>Section:</b> 23.4 [unord] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-05-05</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#unord">active issues</a> in [unord].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#unord">issues</a> in [unord].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Move semantics are missing from the <tt>unordered</tt> containers.  The proposed
resolution below adds move-support consistent with
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1858.html">N1858</a>
and the current working draft.
</p>

<p>
The current proposed resolution simply lists the requirements for each function.
These might better be hoisted into the requirements table for unordered associative containers.
Futhermore a mild reorganization of the container requirements could well be in order.
This defect report is purposefully ignoring these larger issues and just focusing
on getting the unordered containers "moved".
</p>



<p><b>Proposed resolution:</b></p>

<p>
Add to 23.4 [unord]:
</p>

<blockquote><pre>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y); 

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>

template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>

...

template &lt;class Value, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Value, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_set&lt;Value, Hash, Pred, Alloc&gt;&amp; y); 

<ins>template &lt;class Value, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Value, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_set&lt;Value, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Value, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Value, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_set&lt;Value, Hash, Pred, Alloc&gt;&amp; y);</ins>

template &lt;class Value, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Value, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multiset&lt;Value, Hash, Pred, Alloc&gt;&amp; y);

<ins>template &lt;class Value, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Value, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multiset&lt;Value, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Value, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Value, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_multiset&lt;Value, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre></blockquote>

<p><b><tt>unordered_map</tt></b></p>

<p>
Change 23.4.1 [unord.map]:
</p>

<blockquote><pre>class unordered_map
{
    ...
    unordered_map(const unordered_map&amp;);
    <ins>unordered_map(unordered_map&amp;&amp;);</ins>
    ~unordered_map();
    unordered_map&amp; operator=(const unordered_map&amp;);
    <ins>unordered_map&amp; operator=(unordered_map&amp;&amp;);</ins>
    ...
    // modifiers 
    <del>std::</del>pair&lt;iterator, bool&gt; insert(const value_type&amp; obj); 
    <ins>template &lt;class P&gt; pair&lt;iterator, bool&gt; insert(P&amp;&amp; obj);</ins>
    iterator       insert(iterator hint, const value_type&amp; obj);
    <ins>template &lt;class P&gt; iterator       insert(iterator hint, P&amp;&amp; obj);</ins>
    const_iterator insert(const_iterator hint, const value_type&amp; obj);
    <ins>template &lt;class P&gt; const_iterator insert(const_iterator hint, P&amp;&amp; obj);</ins>
    ...
    void swap(unordered_map&amp;<ins>&amp;</ins>);
    ...
    mapped_type&amp; operator[](const key_type&amp; k);
    <ins>mapped_type&amp; operator[](key_type&amp;&amp; k);</ins>
    ...
};

template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre></blockquote>

<p>
Add to 23.4.1.1 [unord.map.cnstr]:
</p>

<blockquote>
<pre>template &lt;class InputIterator&gt;
  unordered_map(InputIterator f, InputIterator l, 
                size_type n = <i>implementation-defined</i>, 
                const hasher&amp; hf = hasher(), 
                const key_equal&amp; eql = key_equal(), 
                const allocator_type&amp; a = allocator_type());
</pre>

<blockquote><p>
<ins>
<i>Requires:</i> If the iterator's dereference operator returns an
lvalue or a const rvalue <tt>pair&lt;key_type, mapped_type&gt;</tt>,
then both <tt>key_type</tt> and <tt>mapped_type</tt> shall be
<tt>CopyConstructible</tt>.
</ins>
</p></blockquote>
</blockquote>

<p>
Add to 23.4.1.2 [unord.map.elem]:
</p>

<blockquote>

<pre>mapped_type&amp; operator[](const key_type&amp; k);</pre>

<blockquote>
<p>...</p>
<p><ins>
<i>Requires:</i> <tt>key_type</tt> shall be <tt>CopyConstructible</tt>
and <tt>mapped_type</tt> shall be <tt>DefaultConstructible</tt>.
</ins></p>
</blockquote>

<pre><ins>mapped_type&amp; operator[](key_type&amp;&amp; k);</ins></pre>

<blockquote>
<p><ins>
<i>Effects:</i> If the <tt>unordered_map</tt> does not already contain an
element whose key is equivalent to <tt>k</tt> , inserts the value
<tt>std::pair&lt;const key_type, mapped_type&gt;(std::move(k), mapped_type())</tt>.
</ins></p>

<p><ins>
<i>Requires:</i> <tt>mapped_type</tt> shall be <tt>DefaultConstructible</tt>.
</ins></p>

<p><ins>
<i>Returns:</i> A reference to <tt>x.second</tt>, where <tt>x</tt> is the
(unique) element whose key is equivalent to <tt>k</tt>.
</ins></p>

</blockquote>

</blockquote>

<p>
Add new section [unord.map.modifiers]:
</p>

<blockquote>
<pre><ins>pair&lt;iterator, bool&gt; insert(const value_type&amp; x);</ins>
<ins>template &lt;class P&gt; pair&lt;iterator, bool&gt; insert(P&amp;&amp; x);</ins>
<ins>iterator       insert(iterator hint, const value_type&amp; x);</ins>
<ins>template &lt;class P&gt; iterator       insert(iterator hint, P&amp;&amp; x);</ins>
<ins>const_iterator insert(const_iterator hint, const value_type&amp; x);</ins>
<ins>template &lt;class P&gt; const_iterator insert(const_iterator hint, P&amp;&amp; x);</ins>
<ins>template &lt;class InputIterator&gt;
  void insert(InputIterator first, InputIterator last);</ins>
</pre>

<blockquote>
<p><ins>
<i>Requires:</i> Those signatures taking a <tt>const value_type&amp;</tt> parameter
requires both the <tt>key_type</tt> and the <tt>mapped_type</tt> to be
<tt>CopyConstructible</tt>.
</ins></p>

<p><ins>
<tt>P</tt> shall be convertible to <tt>value_type</tt>.
 If <tt>P</tt> is instantiated as a reference
type, then the argument <tt>x</tt> is copied from. Otherwise <tt>x</tt>
is considered to be an rvalue as it is converted to <tt>value_type</tt>
and inserted into the <tt>unordered_map</tt>. Specifically, in such
cases <tt>CopyConstructible</tt> is not required of <tt>key_type</tt> or
<tt>mapped_type</tt> unless the conversion from <tt>P</tt> specifically
requires it (e.g. if <tt>P</tt> is a <tt>tuple&lt;const key_type,
mapped_type&gt;</tt>, then <tt>key_type</tt> must be
<tt>CopyConstructible</tt>).
</ins></p>

<p><ins>
The signature taking <tt>InputIterator</tt>
parameters requires <tt>CopyConstructible</tt> of both
<tt>key_type</tt> and <tt>mapped_type</tt> if the dereferenced
<tt>InputIterator</tt> returns an lvalue or <tt>const</tt> rvalue
<tt>value_type</tt>.
</ins></p>

</blockquote>

</blockquote>

<p>
Add to 23.4.1.3 [unord.map.swap]:
</p>

<blockquote>
<pre>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_map&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre>
</blockquote>

<p><b><tt>unordered_multimap</tt></b></p>

<p>
Change 23.4.2 [unord.multimap]:
</p>

<blockquote><pre>class unordered_multimap
{
    ...
    unordered_multimap(const unordered_multimap&amp;);
    <ins>unordered_multimap(unordered_multimap&amp;&amp;);</ins>
    ~unordered_multimap();
    unordered_multimap&amp; operator=(const unordered_multimap&amp;);
    <ins>unordered_multimap&amp; operator=(unordered_multimap&amp;&amp;);</ins>
    ...
    // modifiers 
    iterator insert(const value_type&amp; obj); 
    <ins>template &lt;class P&gt; iterator insert(P&amp;&amp; obj);</ins>
    iterator       insert(iterator hint, const value_type&amp; obj);
    <ins>template &lt;class P&gt; iterator       insert(iterator hint, P&amp;&amp; obj);</ins>
    const_iterator insert(const_iterator hint, const value_type&amp; obj);
    <ins>template &lt;class P&gt; const_iterator insert(const_iterator hint, P&amp;&amp; obj);</ins>
    ...
    void swap(unordered_multimap&amp;<ins>&amp;</ins>);
    ...
};

template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre></blockquote>

<p>
Add to 23.4.2.1 [unord.multimap.cnstr]:
</p>

<blockquote>
<pre>template &lt;class InputIterator&gt;
  unordered_multimap(InputIterator f, InputIterator l, 
                size_type n = <i>implementation-defined</i>, 
                const hasher&amp; hf = hasher(), 
                const key_equal&amp; eql = key_equal(), 
                const allocator_type&amp; a = allocator_type());
</pre>

<blockquote><p>
<ins>
<i>Requires:</i> If the iterator's dereference operator returns an
lvalue or a const rvalue <tt>pair&lt;key_type, mapped_type&gt;</tt>,
then both <tt>key_type</tt> and <tt>mapped_type</tt> shall be
<tt>CopyConstructible</tt>.
</ins>
</p></blockquote>
</blockquote>

<p>
Add new section [unord.multimap.modifiers]:
</p>

<blockquote>
<pre><ins>iterator insert(const value_type&amp; x);</ins>
<ins>template &lt;class P&gt; iterator       insert(P&amp;&amp; x);</ins>
<ins>iterator       insert(iterator hint, const value_type&amp; x);</ins>
<ins>template &lt;class P&gt; iterator       insert(iterator hint, P&amp;&amp; x);</ins>
<ins>const_iterator insert(const_iterator hint, const value_type&amp; x);</ins>
<ins>template &lt;class P&gt; const_iterator insert(const_iterator hint, P&amp;&amp; x);</ins>
<ins>template &lt;class InputIterator&gt;
  void insert(InputIterator first, InputIterator last);</ins>
</pre>

<blockquote>
<p><ins>
<i>Requires:</i> Those signatures taking a <tt>const value_type&amp;</tt> parameter
requires both the <tt>key_type</tt> and the <tt>mapped_type</tt> to be
<tt>CopyConstructible</tt>.
</ins></p>

<p><ins>
<tt>P</tt> shall be convertible to <tt>value_type</tt>.
 If <tt>P</tt> is instantiated as a reference
type, then the argument <tt>x</tt> is copied from. Otherwise <tt>x</tt>
is considered to be an rvalue as it is converted to <tt>value_type</tt>
and inserted into the <tt>unordered_multimap</tt>. Specifically, in such
cases <tt>CopyConstructible</tt> is not required of <tt>key_type</tt> or
<tt>mapped_type</tt> unless the conversion from <tt>P</tt> specifically
requires it (e.g. if <tt>P</tt> is a <tt>tuple&lt;const key_type,
mapped_type&gt;</tt>, then <tt>key_type</tt> must be
<tt>CopyConstructible</tt>).
</ins></p>

<p><ins>
The signature taking <tt>InputIterator</tt>
parameters requires <tt>CopyConstructible</tt> of both
<tt>key_type</tt> and <tt>mapped_type</tt> if the dereferenced
<tt>InputIterator</tt> returns an lvalue or <tt>const</tt> rvalue
<tt>value_type</tt>.
</ins></p>
</blockquote>

</blockquote>

<p>
Add to 23.4.2.2 [unord.multimap.swap]:
</p>

<blockquote>
<pre>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_multimap&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre>
</blockquote>

<p><b><tt>unordered_set</tt></b></p>

<p>
Change 23.4.3 [unord.set]:
</p>

<blockquote><pre>class unordered_set
{
    ...
    unordered_set(const unordered_set&amp;);
    <ins>unordered_set(unordered_set&amp;&amp;);</ins>
    ~unordered_set();
    unordered_set&amp; operator=(const unordered_set&amp;);
    <ins>unordered_set&amp; operator=(unordered_set&amp;&amp;);</ins>
    ...
    // modifiers 
    <del>std::</del>pair&lt;iterator, bool&gt; insert(const value_type&amp; obj); 
    <ins>pair&lt;iterator, bool&gt; insert(value_type&amp;&amp; obj);</ins>
    iterator       insert(iterator hint, const value_type&amp; obj);
    <ins>iterator       insert(iterator hint, value_type&amp;&amp; obj);</ins>
    const_iterator insert(const_iterator hint, const value_type&amp; obj);
    <ins>const_iterator insert(const_iterator hint, value_type&amp;&amp; obj);</ins>
    ...
    void swap(unordered_set&amp;<ins>&amp;</ins>);
    ...
};

template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre></blockquote>

<p>
Add to 23.4.3.1 [unord.set.cnstr]:
</p>

<blockquote>
<pre>template &lt;class InputIterator&gt;
  unordered_set(InputIterator f, InputIterator l, 
                size_type n = <i>implementation-defined</i>, 
                const hasher&amp; hf = hasher(), 
                const key_equal&amp; eql = key_equal(), 
                const allocator_type&amp; a = allocator_type());
</pre>

<blockquote><p>
<ins>
<i>Requires:</i> If the iterator's dereference operator returns an
lvalue or a const rvalue <tt>value_type</tt>, then the
<tt>value_type</tt> shall be <tt>CopyConstructible</tt>.
</ins>
</p></blockquote>
</blockquote>

<p>
Add new section [unord.set.modifiers]:
</p>

<blockquote>
<pre><ins>pair&lt;iterator, bool&gt; insert(const value_type&amp; x);</ins>
<ins>pair&lt;iterator, bool&gt; insert(value_type&amp;&amp; x);</ins>
<ins>iterator       insert(iterator hint, const value_type&amp; x);</ins>
<ins>iterator       insert(iterator hint, value_type&amp;&amp; x);</ins>
<ins>const_iterator insert(const_iterator hint, const value_type&amp; x);</ins>
<ins>const_iterator insert(const_iterator hint, value_type&amp;&amp; x);</ins>
<ins>template &lt;class InputIterator&gt;
  void insert(InputIterator first, InputIterator last);</ins>
</pre>

<blockquote>

<p><ins>
<i>Requires:</i> Those signatures taking a <tt>const
value_type&amp;</tt> parameter requires the <tt>value_type</tt> to
be <tt>CopyConstructible</tt>.
</ins></p>

<p><ins>
The signature taking <tt>InputIterator</tt> parameters requires
<tt>CopyConstructible</tt> of <tt>value_type</tt> if the dereferenced
<tt>InputIterator</tt> returns an lvalue or <tt>const</tt> rvalue
<tt>value_type</tt>.
</ins></p>

</blockquote>

</blockquote>

<p>
Add to 23.4.3.2 [unord.set.swap]:
</p>

<blockquote>
<pre>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_set&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre>
</blockquote>

<p><b><tt>unordered_multiset</tt></b></p>

<p>
Change 23.4.4 [unord.multiset]:
</p>

<blockquote><pre>class unordered_multiset
{
    ...
    unordered_multiset(const unordered_multiset&amp;);
    <ins>unordered_multiset(unordered_multiset&amp;&amp;);</ins>
    ~unordered_multiset();
    unordered_multiset&amp; operator=(const unordered_multiset&amp;);
    <ins>unordered_multiset&amp; operator=(unordered_multiset&amp;&amp;);</ins>
    ...
    // modifiers 
    iterator insert(const value_type&amp; obj); 
    <ins>iterator insert(value_type&amp;&amp; obj);</ins>
    iterator       insert(iterator hint, const value_type&amp; obj);
    <ins>iterator       insert(iterator hint, value_type&amp;&amp; obj);</ins>
    const_iterator insert(const_iterator hint, const value_type&amp; obj);
    <ins>const_iterator insert(const_iterator hint, value_type&amp;&amp; obj);</ins>
    ...
    void swap(unordered_multiset&amp;<ins>&amp;</ins>);
    ...
};

template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>

<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre></blockquote>

<p>
Add to 23.4.4.1 [unord.multiset.cnstr]:
</p>

<blockquote>
<pre>template &lt;class InputIterator&gt;
  unordered_multiset(InputIterator f, InputIterator l, 
                size_type n = <i>implementation-defined</i>, 
                const hasher&amp; hf = hasher(), 
                const key_equal&amp; eql = key_equal(), 
                const allocator_type&amp; a = allocator_type());
</pre>

<blockquote><p>
<ins>
<i>Requires:</i> If the iterator's dereference operator returns an
lvalue or a const rvalue <tt>value_type</tt>, then the
<tt>value_type</tt> shall be <tt>CopyConstructible</tt>.
</ins>
</p></blockquote>
</blockquote>

<p>
Add new section [unord.multiset.modifiers]:
</p>

<blockquote>
<pre><ins>iterator insert(const value_type&amp; x);</ins>
<ins>iterator insert(value_type&amp;&amp; x);</ins>
<ins>iterator       insert(iterator hint, const value_type&amp; x);</ins>
<ins>iterator       insert(iterator hint, value_type&amp;&amp; x);</ins>
<ins>const_iterator insert(const_iterator hint, const value_type&amp; x);</ins>
<ins>const_iterator insert(const_iterator hint, value_type&amp;&amp; x);</ins>
<ins>template &lt;class InputIterator&gt;
  void insert(InputIterator first, InputIterator last);</ins>
</pre>

<blockquote>

<p><ins>
<i>Requires:</i> Those signatures taking a <tt>const
value_type&amp;</tt> parameter requires the <tt>value_type</tt> to
be <tt>CopyConstructible</tt>.
</ins></p>

<p><ins>
The signature taking <tt>InputIterator</tt> parameters requires
<tt>CopyConstructible</tt> of <tt>value_type</tt> if the dereferenced
<tt>InputIterator</tt> returns an lvalue or <tt>const</tt> rvalue
<tt>value_type</tt>.
</ins></p>

</blockquote>

</blockquote>

<p>
Add to 23.4.4.2 [unord.multiset.swap]:
</p>

<blockquote>
<pre>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; x, 
            unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; y);</ins>
<ins>template &lt;class Key, class T, class Hash, class Pred, class Alloc&gt; 
  void swap(unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp;&amp; x, 
            unordered_multiset&lt;Key, T, Hash, Pred, Alloc&gt;&amp; y);</ins>
</pre>
</blockquote>






<hr>
<h3><a name="679"></a>679. resize parameter by value</h3>
<p><b>Section:</b> 23.2 [sequences] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-06-11</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The C++98 standard specifies that one member function alone of the containers
passes its parameter (<tt>T</tt>) by value instead of by const reference:
</p>

<blockquote><pre>void resize(size_type sz, T c = T());
</pre></blockquote>

<p>
This fact has been discussed / debated repeatedly over the years, the first time
being even before C++98 was ratified.  The rationale for passing this parameter by
value has been:
</p>

<blockquote>
<p>
So that self referencing statements are guaranteed to work, for example:
</p>
<blockquote><pre>v.resize(v.size() + 1, v[0]);
</pre></blockquote>
</blockquote>

<p>
However this rationale is not convincing as the signature for <tt>push_back</tt> is:
</p>

<blockquote><pre>void push_back(const T&amp; x);
</pre></blockquote>

<p>
And <tt>push_back</tt> has similar semantics to <tt>resize</tt> (append).
And <tt>push_back</tt> must also work in the self referencing case:
</p>

<blockquote><pre>v.push_back(v[0]);  // must work
</pre></blockquote>

<p>
The problem with passing <tt>T</tt> by value is that it can be significantly more
expensive than passing by reference.  The converse is also true, however when it is
true it is usually far less dramatic (e.g. for scalar types).
</p>

<p>
Even with move semantics available, passing this parameter by value can be expensive.
Consider for example <tt>vector&lt;vector&lt;int&gt;&gt;</tt>:
</p>

<blockquote><pre>std::vector&lt;int&gt; x(1000);
std::vector&lt;std::vector&lt;int&gt;&gt; v;
...
v.resize(v.size()+1, x);
</pre></blockquote>

<p>
In the pass-by-value case, <tt>x</tt> is copied once to the parameter of
<tt>resize</tt>.  And then internally, since the code can not know at compile
time by how much <tt>resize</tt> is growing the <tt>vector</tt>, <tt>x</tt> is
usually copied (not moved) a second time from <tt>resize</tt>'s parameter into its proper place
within the <tt>vector</tt>.
</p>

<p>
With pass-by-const-reference, the <tt>x</tt> in the above example need be copied
only once.  In this case, <tt>x</tt> has an expensive copy constructor and so any
copies that can be saved represents a significant savings.
</p>

<p>
If we can be efficient for <tt>push_back</tt>, we should be efficient for <tt>resize</tt>
as well.  The resize taking a reference parameter has been coded and shipped in the
CodeWarrior library with no reports of problems which I am aware of.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change 23.2.2 [deque], p2:
</p>

<blockquote><pre>class deque {
   ...
   void resize(size_type sz, <ins>const </ins>T<ins>&amp;</ins> c);
</pre></blockquote>

<p>
Change 23.2.2.2 [deque.capacity], p3:
</p>

<blockquote><pre>void resize(size_type sz, <ins>const </ins>T<ins>&amp;</ins> c);
</pre></blockquote>

<p>
Change 23.2.3 [list], p2:
</p>

<blockquote><pre>class list {
   ...
   void resize(size_type sz, <ins>const </ins>T<ins>&amp;</ins> c);
</pre></blockquote>

<p>
Change 23.2.3.2 [list.capacity], p3:
</p>

<blockquote><pre>void resize(size_type sz, <ins>const </ins>T<ins>&amp;</ins> c);
</pre></blockquote>

<p>
Change 23.2.5 [vector], p2:
</p>

<blockquote><pre>class vector {
   ...
   void resize(size_type sz, <ins>const </ins>T<ins>&amp;</ins> c);
</pre></blockquote>

<p>
Change 23.2.5.2 [vector.capacity], p11:
</p>

<blockquote><pre>void resize(size_type sz, <ins>const </ins>T<ins>&amp;</ins> c);
</pre></blockquote>






<hr>
<h3><a name="680"></a>680. move_iterator operator-&gt; return</h3>
<p><b>Section:</b> 24.4.3.1 [move.iterator] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-06-11</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<tt>move_iterator</tt>'s <tt>operator-&gt;</tt> return type <tt>pointer</tt>
does not consistently match the type which is returned in the description
in 24.4.3.3.5 [move.iter.op.ref].
</p>

<blockquote><pre>template &lt;class Iterator&gt;
class move_iterator {
public:
    ...
    typedef typename iterator_traits&lt;Iterator&gt;::pointer pointer;
    ...
    pointer operator-&gt;() const {return current;}
    ...
private: 
    Iterator current; // exposition only
};
</pre></blockquote>


<p>
There are two possible fixes.
</p>

<ol>
<li><tt>pointer operator-&gt;() const {return &amp;*current;}</tt></li>
<li><tt>typedef Iterator pointer;</tt></li>
</ol>

<p>
The first solution is the one chosen by <tt>reverse_iterator</tt>.  A potential
disadvantage of this is it may not work well with iterators which return a
proxy on dereference and that proxy has overloaded <tt>operator&amp;()</tt>.  Proxy
references often need to overloaad <tt>operator&amp;()</tt> to return a proxy
pointer.  That proxy pointer may or may not be the same type as the iterator's
<tt>pointer</tt> type.
</p>

<p>
By simply returning the <tt>Iterator</tt> and taking advantage of the fact that
the language forwards calls to <tt>operator-&gt;</tt> automatically until it
finds a non-class type, the second solution avoids the issue of an overloaded
<tt>operator&amp;()</tt> entirely.
</p>

<p><b>Proposed resolution:</b></p>
<p>
Change the synopsis in 24.4.3.1 [move.iterator]:
</p>

<blockquote><pre>typedef <del>typename iterator_traits&lt;</del>Iterator<del>&gt;::pointer</del> pointer;
</pre></blockquote>






<hr>
<h3><a name="684"></a>684. Unclear which members of match_results should be used in comparison</h3>
<p><b>Section:</b> 28.10 [re.results] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Nozomu Katoo <b>Date:</b> 2007-05-27</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#re.results">active issues</a> in [re.results].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#re.results">issues</a> in [re.results].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In 28.4 [re.syn] of N2284, two template functions 
are declared here: 
</p>
<blockquote><pre>// 28.10, class template match_results: 
&nbsp; &lt;<i>snip</i>&gt;
// match_results comparisons 
&nbsp; template &lt;class BidirectionalIterator, class Allocator&gt; 
&nbsp; &nbsp; bool operator== (const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2); 
&nbsp; template &lt;class BidirectionalIterator, class Allocator&gt; 
&nbsp; &nbsp; bool operator!= (const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2); 

// 28.10.6, match_results swap:
</pre></blockquote>

<p>
But the details of these two bool operator functions (i.e., which members of
<tt>match_results</tt> should be used in comparison) are not described in any
following sections.
</p>

<p><i>[
John adds:
]</i></p>


<blockquote><p>
That looks like a bug: <tt>operator==</tt> should return <tt>true</tt> only if
the two objects refer to the same match - ie if one object was constructed as a
copy of the other.
</p></blockquote>

<p><i>[
Kona (2007): Bill and Pete to add minor wording to that proposed in
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2409.pdf">N2409</a>.
]</i></p>



<p><b>Proposed resolution:</b></p>
<p>
Add a new section after 28.10.6 [re.results.swap], which reads:
</p>
<p>
28.10.7 match_results non-member functions.
</p>

<blockquote>
<pre>template&lt;class BidirectionalIterator, class Allocator&gt; 
  bool operator==(const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1, 
                  const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>true</tt> only if the two objects refer to the same match.
</p>
</blockquote>
</blockquote>

<blockquote>
<pre>template&lt;class BidirectionalIterator, class Allocator&gt; 
  bool operator!=(const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1, 
                  const match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>!(m1 == m2)</tt>.
</p>
</blockquote>
</blockquote>

<blockquote>
<pre>template&lt;class BidirectionalIterator, class Allocator&gt; 
  void swap(match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m1, 
            match_results&lt;BidirectionalIterator, Allocator&gt;&amp; m2);
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>m1.swap(m2)</tt>.
</p>
</blockquote>
</blockquote>





<hr>
<h3><a name="685"></a>685. reverse_iterator/move_iterator difference has invalid signatures</h3>
<p><b>Section:</b> 24.4.1.3.19 [reverse.iter.opdiff], 24.4.3.3.14 [move.iter.nonmember] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Bo Persson <b>Date:</b> 2007-06-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In C++03 the difference between two <tt>reverse_iterators</tt>
</p>
<blockquote><pre>ri1 - ri2
</pre></blockquote>
<p>
is possible to compute only if both iterators have the same base 
iterator. The result type is the <tt>difference_type</tt> of the base iterator. 
</p>
<p>
In the current draft, the operator is defined as 24.4.1.3.19 [reverse.iter.opdiff] 
</p>
<blockquote><pre>template&lt;class Iterator1, class Iterator2&gt; 
typename reverse_iterator&lt;Iterator&gt;::difference_type 
&nbsp; &nbsp;operator-(const reverse_iterator&lt;Iterator1&gt;&amp; x, 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; const reverse_iterator&lt;Iterator2&gt;&amp; y);
</pre></blockquote>
<p>
The return type is the same as the C++03 one, based on the no longer 
present <tt>Iterator</tt> template parameter. 
</p>
<p>
Besides being slightly invalid, should this operator work only when 
<tt>Iterator1</tt> and <tt>Iterator2</tt> has the same <tt>difference_type</tt>? Or should the 
implementation choose one of them? Which one? 
</p>
<p>
The same problem now also appears in <tt>operator-()</tt> for <tt>move_iterator</tt>
24.4.3.3.14 [move.iter.nonmember]. 
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change the synopsis in 24.4.1.1 [reverse.iterator]:
</p>

<blockquote>
<pre>template &lt;class Iterator1, class Iterator2&gt; 
  <del>typename reverse_iterator&lt;Iterator&gt;::difference_type</del> <ins>auto</ins> operator-( 
    const reverse_iterator&lt;Iterator1&gt;&amp; x, 
    const reverse_iterator&lt;Iterator2&gt;&amp; y)<ins> -&gt; decltype(operator-(Iterator1, Iterator2))</ins>;
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>y.current - x.current</tt>.
</p>
</blockquote>
</blockquote>

<p>
Change 24.4.1.3.19 [reverse.iter.opdiff]:
</p>

<blockquote>
<pre>template &lt;class Iterator1, class Iterator2&gt; 
  <del>typename reverse_iterator&lt;Iterator&gt;::difference_type</del> <ins>auto</ins> operator-( 
    const reverse_iterator&lt;Iterator1&gt;&amp; x, 
    const reverse_iterator&lt;Iterator2&gt;&amp; y)<ins> -&gt; decltype(operator-(Iterator1, Iterator2))</ins>;
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>y.current - x.current</tt>.
</p>
</blockquote>
</blockquote>


<p>
Change the synopsis in 24.4.3.1 [move.iterator]:
</p>

<blockquote>
<pre>template &lt;class Iterator1, class Iterator2&gt; 
  <del>typename move_iterator&lt;Iterator&gt;::difference_type</del> <ins>auto</ins> operator-( 
    const move_iterator&lt;Iterator1&gt;&amp; x, 
    const move_iterator&lt;Iterator2&gt;&amp; y)<ins> -&gt; decltype(operator-(Iterator1, Iterator2))</ins>;
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>y.current - x.current</tt>.
</p>
</blockquote>
</blockquote>

<p>
Change 24.4.3.3.14 [move.iter.nonmember]:
</p>

<blockquote>
<pre>template &lt;class Iterator1, class Iterator2&gt; 
  <del>typename move_iterator&lt;Iterator&gt;::difference_type</del> <ins>auto</ins> operator-( 
    const move_iterator&lt;Iterator1&gt;&amp; x, 
    const move_iterator&lt;Iterator2&gt;&amp; y)<ins> -&gt; decltype(operator-(Iterator1, Iterator2))</ins>;
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>x.base() - y.base()</tt>.
</p>
</blockquote>
</blockquote>





<hr>
<h3><a name="686"></a>686. Unique_ptr and shared_ptr fail to specify non-convertibility to int for unspecified-bool-type</h3>
<p><b>Section:</b> 20.6.5.2.4 [unique.ptr.single.observers], 20.6.6.2.5 [util.smartptr.shared.obs] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Beman Dawes <b>Date:</b> 2007-06-14</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The standard library uses the <tt>operator <i>unspecified-bool-type</i>() const</tt> idiom in
five places. In three of those places (20.5.15.2.3 [func.wrap.func.cap], function capacity 
for example) the returned value is constrained to disallow
unintended conversions to int. The standardese is
</p>
<blockquote><p>
The return type shall not be convertible to <tt>int</tt>.
</p></blockquote>
<p>
This constraint is omitted for <tt>unique_ptr</tt> and <tt>shared_ptr</tt>. It should be added for those.
</p>


<p><b>Proposed resolution:</b></p>
<p>
To the <i>Returns</i> paragraph for <tt>operator <i>unspecified-bool-type</i>()
const</tt>
of 20.6.5.2.4 [unique.ptr.single.observers] paragraph 11 and 20.6.6.2.5
[util.smartptr.shared.obs] paragraph 16, add the sentence:
</p>
<blockquote><p>
The return type shall not be convertible to <tt>int</tt>.
</p></blockquote>


<p><i>[
Kona (2007): Uncertain if <tt>nullptr</tt> will address this issue.
]</i></p>





<hr>
<h3><a name="687"></a>687. shared_ptr conversion constructor not constrained</h3>
<p><b>Section:</b> 20.6.6.2.1 [util.smartptr.shared.const], 20.6.6.3.1 [util.smartptr.weak.const] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-05-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Since all conversions from <tt>shared_ptr&lt;T&gt;</tt> to <tt>shared_ptr&lt;U&gt;</tt> have the same
rank regardless of the relationship between <tt>T</tt> and <tt>U</tt>, reasonable user
code that works with raw pointers fails with <tt>shared_ptr</tt>:
</p>

<blockquote><pre>void f( shared_ptr&lt;void&gt; );
void f( shared_ptr&lt;int&gt; );

int main()
{
&nbsp;&nbsp;f( shared_ptr&lt;double&gt;() ); // ambiguous
}
</pre></blockquote>

<p>
Now that we officially have <tt>enable_if</tt>, we can constrain the constructor
and the corresponding assignment operator to only participate in the
overload resolution when the pointer types are compatible.
</p>


<p><b>Proposed resolution:</b></p>
<p>
In 20.6.6.2.1 [util.smartptr.shared.const], change:
</p>

<blockquote><p>
-14- <i>Requires:</i> <del>For the second constructor</del> <ins>The
second constructor shall not participate in the overload resolution
unless</ins> <tt>Y*</tt> <del>shall be</del> <ins>is implicitly</ins> convertible
to <tt>T*</tt>.
</p></blockquote>

<p>
In 20.6.6.3.1 [util.smartptr.weak.const], change:
</p>

<blockquote>
<pre><del>template&lt;class Y&gt; weak_ptr(shared_ptr&lt;Y&gt; const&amp; r);</del>
<del>weak_ptr(weak_ptr const&amp; r);</del>
<del>template&lt;class Y&gt; weak_ptr(weak_ptr&lt;Y&gt; const&amp; r);</del>
<ins>weak_ptr(weak_ptr const&amp; r);</ins>
<ins>template&lt;class Y&gt; weak_ptr(weak_ptr&lt;Y&gt; const&amp; r);</ins>
<ins>template&lt;class Y&gt; weak_ptr(shared_ptr&lt;Y&gt; const&amp; r);</ins>
</pre>
<blockquote><p>
-4- <i>Requires:</i> <del>For</del> <del>t</del><ins>T</ins>he second and
third constructors<del>,</del> <ins>shall not participate in the
overload resolution unless</ins> <tt>Y*</tt> <del>shall be</del>
<ins>is implicitly</ins> convertible to <tt>T*</tt>.
</p></blockquote>
</blockquote>






<hr>
<h3><a name="688"></a>688. reference_wrapper, cref unsafe, allow binding to rvalues</h3>
<p><b>Section:</b> 20.5.5.1 [refwrap.const] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-05-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#refwrap.const">active issues</a> in [refwrap.const].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#refwrap.const">issues</a> in [refwrap.const].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
A <tt>reference_wrapper</tt> can be constructed from an rvalue, either by using
the constructor, or via <tt>cref</tt> (and <tt>ref</tt> in some corner cases). This leads
to a dangling reference being stored into the <tt>reference_wrapper</tt> object.
Now that we have a mechanism to detect an rvalue, we can fix them to
disallow this source of undefined behavior.
</p>

<p>
Also please see the thread starting at c++std-lib-17398 for some good discussion on this subject.
</p>



<p><b>Proposed resolution:</b></p>
<p>
In 20.5.5 [refwrap], add:
</p>

<blockquote><pre><ins>private:</ins>
<ins>&nbsp;&nbsp;explicit reference_wrapper(T&amp;&amp;);</ins>
</pre></blockquote>

<p>
In 20.5.5.1 [refwrap.const], add:
</p>

<blockquote>
<pre><ins>explicit reference_wrapper(T&amp;&amp;);</ins>
</pre>
<blockquote><p>
<ins>-?- Not defined to disallow creating a <tt>reference_wrapper</tt> from an rvalue.</ins>
</p></blockquote>
</blockquote>

<p>
In the synopsis of <tt>&lt;functional&gt;</tt> (20.5.5 [refwrap]), change the declarations
of <tt>ref</tt> and <tt>cref</tt> to:
</p>

<blockquote><pre>template&lt;class T&gt; reference_wrapper&lt;T&gt; ref(T&amp;<ins>&amp;</ins>);
template&lt;class T&gt; reference_wrapper&lt;const T&gt; cref(<del>const</del> T&amp;<ins>&amp;</ins>);
</pre></blockquote>

<p>
In 20.5.5.5 [refwrap.helpers], change:
</p>

<blockquote>
<pre>template&lt;class T&gt; reference_wrapper&lt;T&gt; ref(T&amp;<ins>&amp;</ins> t);
</pre>
<blockquote>
<p>
<ins>-1- <i>Requires:</i> <tt>t</tt> shall be an lvalue.</ins>
</p>
</blockquote>
</blockquote>

<p>and change:</p>

<blockquote>
<pre>template&lt;class T&gt; reference_wrapper&lt;const T&gt; cref(<del>const</del> T&amp;<ins>&amp;</ins> t);
</pre>
<blockquote>
<p>
<ins>-6- <i>Requires:</i> <tt>t</tt> shall be an lvalue.</ins>
</p>
</blockquote>
</blockquote>



<p><i>[
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2292.html">N2292</a>
addresses the first part of the resolution but not the second.
]</i></p>





<hr>
<h3><a name="689"></a>689. reference_wrapper constructor overly constrained</h3>
<p><b>Section:</b> 20.5.5.1 [refwrap.const] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-05-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#refwrap.const">active issues</a> in [refwrap.const].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#refwrap.const">issues</a> in [refwrap.const].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The constructor of <tt>reference_wrapper</tt> is currently <tt>explicit</tt>. The primary
motivation behind this is the safety problem with respect to rvalues,
which is addressed by the proposed resolution of the previous issue.
Therefore we should consider relaxing the requirements on the
constructor since requests for the implicit conversion keep resurfacing.
</p>
<p>
Also please see the thread starting at c++std-lib-17398 for some good discussion on this subject.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Remove the <tt>explicit</tt> from the constructor of <tt>reference_wrapper</tt>. If the
proposed resolution of the previous issue is accepted, remove the
<tt>explicit</tt> from the <tt>T&amp;&amp;</tt> constructor as well to keep them in sync.
</p>





<hr>
<h3><a name="691"></a>691. const_local_iterator cbegin, cend missing from TR1</h3>
<p><b>Section:</b> 23.4 [unord], TR1 6.3 [tr.hash] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Review">Review</a>
 <b>Submitter:</b> Joaquín M López Muñoz <b>Date:</b> 2007-06-14</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#unord">active issues</a> in [unord].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#unord">issues</a> in [unord].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Review">Review</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The last version of TR1 does not include the following member
functions
for unordered containers:
</p>

<blockquote><pre>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
</pre></blockquote>

<p>
which looks like an oversight to me. I've checked th TR1 issues lists
and the latest working draft of the C++0x std (N2284) and haven't
found any mention to these menfuns or to their absence.
</p>
<p>
Is this really an oversight, or am I missing something?
</p>



<p><b>Proposed resolution:</b></p>
<p>
Add the following two rows to table 93 (unordered associative container
requirements) in section 23.1.3 [unord.req]:
</p>

<blockquote>
<table border="1">
<caption>Unordered associative container requirements (in addition to container)</caption>
<tbody><tr>
<th>expression</th> <th>return type</th> <th>assertion/note pre/post-condition</th> <th>complexity</th>
</tr>
<tr>
<td><ins><tt>b.cbegin(n)</tt></ins></td> <td><ins><tt>const_local_iterator</tt></ins></td> <td><ins><tt>n</tt> shall be in the range <tt>[0, bucket_count())</tt>. Note: <tt>[b.cbegin(n), b.cend(n))</tt> is a valid range containing all of the elements in the <tt>n</tt><sup><i>th</i></sup> bucket.</ins></td> <td><ins>Constant</ins></td> 
</tr>
<tr>
<td><ins><tt>b.cend(n)</tt></ins></td> <td><ins><tt>const_local_iterator</tt></ins></td> <td><ins><tt>n</tt> shall be in the range <tt>[0, bucket_count())</tt>.</ins></td> <td><ins>Constant</ins></td> 
</tr>
</tbody></table>
</blockquote>

<p>
Add to the synopsis in 23.4.1 [unord.map]:
</p>

<blockquote><pre><ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>

<p>
Add to the synopsis in 23.4.2 [unord.multimap]:
</p>

<blockquote><pre><ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>

<p>
Add to the synopsis in 23.4.3 [unord.set]:
</p>

<blockquote><pre><ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>

<p>
Add to the synopsis in 23.4.4 [unord.multiset]:
</p>

<blockquote><pre><ins>const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;</ins>
</pre></blockquote>






<hr>
<h3><a name="692"></a>692. <code>get_money</code> and <code>put_money</code> should be&nbsp;formatted I/O functions</h3>
<p><b>Section:</b> 27.6.4 [ext.manip] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-06-22</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#ext.manip">issues</a> in [ext.manip].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In a private email Bill Plauger notes:
</p>
<blockquote><p>
I &nbsp;believe that &nbsp;the function &nbsp;that &nbsp;implements <code>get_money</code>
[from <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2072.html">N2072</a>]
should behave &nbsp;as a &nbsp;formatted input function, &nbsp;and the &nbsp;function that
implements <code>put_money</code> should &nbsp;behave as a formatted output
function. This &nbsp;has implications regarding the &nbsp;skipping of whitespace
and the handling of errors, among other things.
</p>
<p>
The words &nbsp;don't say that &nbsp;right now and &nbsp;I'm far from &nbsp;convinced that
such a change is editorial.
</p></blockquote>
<p>
Martin's response:
</p>
<blockquote><p>
I agree that the manipulators should handle exceptions the same way as
formatted I/O functions do. The text in N2072 assumes so but the
<i>Returns</i> clause explicitly omits exception handling for the sake
of brevity. The spec should be clarified to that effect.
</p>
<p>
As for dealing &nbsp;with whitespace, I also agree it &nbsp;would make sense for
the extractors &nbsp;and inserters involving the new &nbsp;manipulators to treat
it the same way as formatted I/O.
</p></blockquote>


<p><b>Proposed resolution:</b></p>
<p>
Add &nbsp;a new &nbsp;paragraph immediately &nbsp;above &nbsp;p4 of 27.6.4 [ext.manip] with &nbsp;the
following text:
</p>
<blockquote><p>
<i>Effects</i>: &nbsp;The &nbsp;&nbsp;expression &nbsp;<code><i>in</i> &gt;&gt; get_money(mon, intl)</code>
described below behaves as a formatted input function (as
described in 27.6.1.2.1 [istream.formatted.reqmts]).
</p></blockquote>
<p>
Also change p4 of 27.6.4 [ext.manip] as follows:
</p>
<blockquote><p>
<i>Returns</i>: An object <code>s</code> of unspecified type such that
if <code>in</code> is &nbsp;an object of type <code>basic_istream&lt;charT,
traits&gt;</code> &nbsp;&nbsp;&nbsp;then &nbsp;&nbsp;&nbsp;the &nbsp;&nbsp;&nbsp;expression &nbsp;&nbsp;<code><i>in</i> &gt;&gt; get_money(mon, intl)</code> behaves as <ins>a formatted input function
that &nbsp;&nbsp;&nbsp;calls &nbsp;&nbsp;&nbsp;</ins><code>f(in, mon, intl)</code><del> &nbsp;&nbsp;&nbsp;were
called</del>. The function <code>f</code> can be defined as...
</p></blockquote>





<hr>
<h3><a name="693"></a>693. <code>std::bitset::all()</code> missing</h3>
<p><b>Section:</b> 23.3.5 [template.bitset] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-06-22</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#template.bitset">active issues</a> in [template.bitset].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#template.bitset">issues</a> in [template.bitset].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The  <code>bitset</code> class template  provides the  member function
<code>any()</code> to determine whether an  object of the type has any
bits  set, and  the member  function <code>none()</code>  to determine
whether all of an object's  bits are clear. However, the template does
not   provide  a   corresponding  function   to  discover   whether  a
<code>bitset</code>  object  has  all  its  bits  set.   While  it  is
possible,  even easy,  to  obtain this  information  by comparing  the
result of <code>count()</code>  with the result of <code>size()</code>
for  equality  (i.e.,  via  <code>b.count()  ==  b.size()</code>)  the
operation  is   less  efficient   than  a  member   function  designed
specifically  for that purpose  could be.   (<code>count()</code> must
count  all non-zero bits  in a  <code>bitset</code> a  word at  a time
while <code>all()</code> could stop counting as soon as it encountered
the first word with a zero bit).
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add  a declaration of the new  member function <code>all()</code> to the
defintion of the <code>bitset</code> template in 23.3.5 [template.bitset], p1,
right above the declaration of <code>any()</code> as shown below:
</p>

<blockquote><pre>bool operator!=(const bitset&lt;N&gt;&amp; rhs) const;
bool test(size_t pos) const;
<ins>bool all() const;</ins>
bool any() const;
bool none() const;
</pre></blockquote>

<p>
Add a description of the new member function to the end of 23.3.5.2 [bitset.members] with the following text:
</p>
<blockquote><p>
<code>bool all() const;</code>
</p>
<blockquote>
<i>Returns</i>: <code>count() == size()</code>.
</blockquote>
</blockquote>

<p>
In  addition,   change  the  description   of  <code>any()</code>  and
<code>none()</code>   for  consistency   with   <code>all()</code>  as
follows:
</p>
<blockquote><p>
<code>bool any() const;</code>
</p>
<blockquote>
<p>
<i>Returns</i>: <del><code>true</code> if any bit in <code>*this</code>
is one</del><ins><code>count() != 0</code></ins>.
</p>
</blockquote>
<p>
<code>bool none() const;</code>
</p>
<blockquote>
<p>
<i>Returns</i>: <del><code>true</code> if no bit in <code>*this</code>
is one</del><ins><code>count() == 0</code></ins>.
</p>
</blockquote>
</blockquote>





<hr>
<h3><a name="694"></a>694. <code>std::bitset</code> and <code>long long</code></h3>
<p><b>Section:</b> 23.3.5 [template.bitset] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-06-22</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#template.bitset">active issues</a> in [template.bitset].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#template.bitset">issues</a> in [template.bitset].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Objects of the  <code>bitset</code> class template specializations can
be constructed from  and explicitly converted to values  of the widest
C++ integer  type, <code>unsigned long</code>.   With the introduction
of  <code>long long</code> into  the language  the template  should be
enhanced to make it possible  to interoperate with values of this type
as well, or  perhaps <code>uintmax_t</code>.  See c++std-lib-18274 for
a brief discussion in support of this change.
</p>


<p><b>Proposed resolution:</b></p>
<p>
For simplicity,  instead of  adding overloads for  <code>unsigned long
long</code> and dealing with possible ambiguities in the spec, replace
the <code>bitset</code> ctor  that takes an <code>unsigned long</code>
argument  with  one  taking  <code>unsigned long  long</code>  in  the
definition  of the  template as  shown below.   (The  standard permits
implementations  to add  overloads on  other integer  types  or employ
template tricks to  achieve the same effect provided  they don't cause
ambiguities or changes in behavior.)
</p>
<blockquote>
<pre>// [bitset.cons] constructors:
bitset();
bitset(unsigned <ins>long</ins> long val);
template&lt;class charT, class traits, class Allocator&gt;
explicit bitset(
                const basic_string&lt;charT,traits,Allocator&gt;&amp; str,
                typename basic_string&lt;charT,traits,Allocator&gt;::size_type pos = 0,
                typename basic_string&lt;charT,traits,Allocator&gt;::size_type n =
                    basic_string&lt;charT,traits,Allocator&gt;::npos);
</pre>
</blockquote>
<p>
Make a corresponding change in 23.3.5.1 [bitset.cons], p2:
</p>
<blockquote>
<p>
<code>bitset(unsigned <ins>long</ins> long val);</code>
</p>
<blockquote>
<i>Effects</i>:  Constructs   an  object  of   class  bitset&lt;N&gt;,
initializing  the  first <code><i>M</i></code>  bit  positions to  the
corresponding      bit     values      in     <code><i>val</i></code>.
<code><i>M</i></code> is the  smaller of <code><i>N</i></code> and the
number of bits in  the value representation (section [basic.types]) of
<code>unsigned  <ins> long</ins> long</code>.   If  <code><i>M</i> &lt;
<i>N</i></code>  <ins>is  <code>true</code></ins>,  the remaining  bit
positions are initialized to zero.
</blockquote>
</blockquote>

<p>
Additionally, introduce a new member function <code>to_ullong()</code>
to make  it possible to  convert <code>bitset</code> to values  of the
new  type. Add  the following  declaration  to the  definition of  the
template, immediate  after the declaration  of <code>to_ulong()</code>
in 23.3.5 [template.bitset], p1, as shown below:
</p>
<blockquote>
<pre>// element access:
bool operator[](size_t pos) const; // for b[i];
reference operator[](size_t pos); // for b[i];
unsigned long to_ulong() const;
<ins>unsigned long long to_ullong() const;</ins>
template &lt;class charT, class traits, class Allocator&gt;
basic_string&lt;charT, traits, Allocator&gt; to_string() const;
</pre>
</blockquote>
<p>
And add a description of  the new member function to 23.3.5.2 [bitset.members],
below  the  description of  the  existing <code>to_ulong()</code>  (if
possible), with the following text:
</p>
<blockquote>
<p>
<code>unsigned long long to_ullong() const;</code>
</p>
<blockquote>
<i>Throws</i>:  <code>overflow_error</code>   if  the  integral  value
<code><i>x</i></code> corresponding to  the bits in <code>*this</code>
cannot be represented as type <code>unsigned long long</code>.
</blockquote>
<blockquote>
<i>Returns:</i> <code><i>x</i></code>.
</blockquote>
</blockquote>





<hr>
<h3><a name="695"></a>695. ctype&lt;char&gt;::classic_table() not accessible</h3>
<p><b>Section:</b> 22.2.1.3 [facet.ctype.special] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-06-22</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The   <code>ctype&lt;char&gt;::classic_table()</code>   static  member
function    returns    a    pointer    to   an    array    of    const
<code>ctype_base::mask</code>    objects    (enums)   that    contains
<code>ctype&lt;char&gt;::table_size</code>    elements.    The   table
describes the properties of the character set in the "C" locale (i.e.,
whether a  character at an index  given by its value  is alpha, digit,
punct,   etc.),   and   is    typically   used   to   initialize   the
<code>ctype&lt;char&gt;</code>  facet in the  classic "C"  locale (the
protected      <code>ctype&lt;char&gt;</code>      member     function
<code>table()</code>    then    returns     the    same    value    as
<code>classic_table()</code>).
</p>
<p>
However, while <code>ctype&lt;char&gt;::table_size</code> (the size of
the   table)    is   a   public    static   const   member    of   the
<code>ctype&lt;char&gt;</code>           specialization,           the
<code>classic_table()</code> static member function is protected. That
makes getting at the classic  data less than convenient (i.e., one has
to create  a whole derived class just  to get at the  masks array). It
makes  little sense  to expose  the size  of the  table in  the public
interface while making the table itself protected, especially when the
table is a constant object.
</p>
<p>
The  same argument  can be  made for  the non-static  protected member
function <code>table()</code>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Make     the    <code>ctype&lt;char&gt;::classic_table()</code>    and
<code>ctype&lt;char&gt;::table()</code>  member  functions  public  by
moving their declarations into the public section of the definition of
specialization in 22.2.1.3 [facet.ctype.special] as shown below:
</p>
<blockquote>
<pre>  static locale::id id;
  static const size_t table_size = IMPLEMENTATION_DEFINED;
<del>protected:</del>
  const mask* table() const throw();
  static const mask* classic_table() throw();
<ins>protected:</ins>

~ctype(); // virtual
virtual char do_toupper(char c) const;
</pre>
</blockquote>





<hr>
<h3><a name="696"></a>696. <code>istream::operator&gt;&gt;(int&amp;)</code> broken</h3>
<p><b>Section:</b> 27.6.1.2.2 [istream.formatted.arithmetic] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Martin Sebor <b>Date:</b> 2007-06-23</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#istream.formatted.arithmetic">active issues</a> in [istream.formatted.arithmetic].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#istream.formatted.arithmetic">issues</a> in [istream.formatted.arithmetic].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
From message c++std-lib-17897:
</p>
<p>
The  code  shown  in  27.6.1.2.2 [istream.formatted.arithmetic] as  the  "as  if"
implementation  of the  two arithmetic  extractors that  don't  have a
corresponding     <code>num_get</code>     interface    (i.e.,     the
<code>short</code> and <code>int</code>  overloads) is subtly buggy in
how  it  deals  with  <code>EOF</code>, overflow,  and  other  similar
conditions (in addition to containing a few typos).
</p>
<p>
One  problem is  that if  <code>num_get::get()</code> reaches  the EOF
after reading in  an otherwise valid value that  exceeds the limits of
the    narrower    type     (but    not    <code>LONG_MIN</code>    or
<code>LONG_MAX</code>),   it  will   set   <code><i>err</i></code>  to
<code>eofbit</code>.   Because   of  the  if   condition  testing  for
<code>(<i>err</i> == 0)</code>,    the   extractor    won't   set
<code>failbit</code>  (and presumably,  return  a bogus  value to  the
caller).
</p>
<p>
Another  problem with  the code  is that  it never  actually  sets the
argument to  the extracted  value. It can't  happen after the  call to
<code>setstate()</code> since  the function may  throw, so we  need to
show when  and how it's done (we  can't just punt as  say: "it happens
afterwards"). However, it  turns out that showing how  it's done isn't
quite so  easy since  the argument is  normally left unchanged  by the
facet on error  except when the error is due  to a misplaced thousands
separator,  which causes  <code>failbit</code> to  be set  but doesn't
prevent the facet from storing the value.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="697"></a>697. New <tt>&lt;system_error&gt;</tt> header leads to name clashes</h3>
<p><b>Section:</b> 19.4 [syserr] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-06-24</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The most recent state of 
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2241.html">N2241</a>
as well as the current draft
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2284.pdf">N2284</a>
(section 19.4 [syserr], p.2) proposes a
new
enumeration type <tt>posix_errno</tt> immediatly in the namespace <tt>std</tt>. One of
the enumerators has the name <tt>invalid_argument</tt>, or fully qualified:
<tt>std::invalid_argument</tt>. This name clashes with the exception type
<tt>std::invalid_argument</tt>, see 19.1 [std.exceptions]/p.3. This clash makes
e.g. the following snippet invalid:
</p>

<blockquote><pre>#include &lt;system_error&gt;
#include &lt;stdexcept&gt;

void foo() { throw std::invalid_argument("Don't call us - we call you!"); }
</pre></blockquote>

<p>
I propose that this enumeration type (and probably the remaining parts
of
<tt>&lt;system_error&gt;</tt> as well) should be moved into one additional inner
namespace, e.g. <tt>sys</tt> or <tt>system</tt> to reduce foreseeable future clashes
due
to the great number of members that <tt>std::posix_errno</tt> already contains
(Btw.: Why has the already proposed <tt>std::sys</tt> sub-namespace from
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2066.html">N2066</a>
been rejected?). A further clash <em>candidate</em> seems to be
<tt>std::protocol_error</tt>
(a reasonable name for an exception related to a std network library,
I guess).
</p>

<p>
Another possible resolution would rely on the proposed strongly typed
enums,
as described in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2213.pdf">N2213</a>.
But maybe the forbidden implicit conversion to integral types would
make
these enumerators less attractive in this special case?
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>






<hr>
<h3><a name="698"></a>698. Some system_error issues</h3>
<p><b>Section:</b> 19.4.5.1 [syserr.syserr.overview] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-06-24</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In 19.4.5.1 [syserr.syserr.overview] we have the class definition of
<tt>std::system_error</tt>. In contrast to all exception classes, which
are constructible with a <tt>what_arg string</tt> (see 19.1 [std.exceptions],
or <tt>ios_base::failure</tt> in 27.4.2.1.1 [ios::failure]), only overloads with with
<tt>const string&amp;</tt> are possible. For consistency with the re-designed
remaining exception classes this class should also provide
c'tors which accept a const <tt>char* what_arg</tt> string.
</p>
<p>
Please note that this proposed addition makes sense even
considering the given implementation hint for <tt>what()</tt>, because
<tt>what_arg</tt> is required to be set as <tt>what_arg</tt> of the base class
<tt>runtime_error</tt>, which now has the additional c'tor overload
accepting a <tt>const char*</tt>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="700"></a>700. N1856 defines struct <tt>identity</tt></h3>
<p><b>Section:</b> 20.2.2 [forward] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> P.J. Plauger <b>Date:</b> 2007-07-01</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1856.html">N1856</a>
defines struct <tt>identity</tt> in <tt>&lt;utility&gt;</tt> which clashes with
the traditional definition of struct <tt>identity</tt> in <tt>&lt;functional&gt;</tt>
(not standard, but a common extension from old STL). Be nice
if we could avoid this name clash for backward compatibility.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 20.2.2 [forward]:
</p>

<blockquote>
<pre>template &lt;class T&gt; struct identity
{
    typedef T type;
    <ins>const T&amp; operator()(const T&amp; x) const;</ins>
};
</pre>
<blockquote>
<pre><ins>const T&amp; operator()(const T&amp; x) const;</ins>
</pre>
<blockquote>
<p>
<ins><i>Returns:</i> <tt>x</tt>.</ins>
</p>
</blockquote>
</blockquote>

</blockquote>






<hr>
<h3><a name="701"></a>701. assoc laguerre poly's</h3>
<p><b>Section:</b> TR1 5.2.1.1 [tr.num.sf.Lnm] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Christopher Crawford <b>Date:</b> 2007-06-30</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I see that the definition the associated Laguerre
polynomials TR1 5.2.1.1 [tr.num.sf.Lnm] has been corrected since
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1687.pdf">N1687</a>.
However, the draft standard only specifies ranks of integer value <tt>m</tt>,
while the associated Laguerre polynomials are actually valid for real
values of <tt>m &gt; -1</tt>. &nbsp;In the case of non-integer values of <tt>m</tt>, the
definition &nbsp;<tt><i>L</i><sub>n</sub><sup>(m)</sup> = (1/n!)e<sup>x</sup>x<sup>-m</sup> (d/dx)<sup>n</sup> (e<sup>-x</sup>x<sup>m+n</sup>)</tt>
must be used, which also holds for integer values of <tt>m</tt>. &nbsp;See
Abramowitz &amp; Stegun, 22.11.6 for the general case, and 22.5.16-17 for
the integer case.&nbsp;&nbsp;In fact fractional values are most commonly used in
physics, for example to <tt>m = +/- 1/2</tt> to describe the harmonic
oscillator in 1 dimension, and <tt>1/2, 3/2, 5/2, ...</tt> in 3
dimensions.
</p>
<p>
If I am correct, the calculation of the more general case is no
more difficult, and is in fact the function implemented in the GNU
Scientific Library.&nbsp;&nbsp;I would urge you to consider upgrading the 
standard, either adding extra functions for real <tt>m</tt> or switching the
current ones to <tt>double</tt>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="702"></a>702. Restriction in associated Legendre functions</h3>
<p><b>Section:</b> TR1 5.2.1.2 [tr.num.sf.Plm] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Christopher Crawford <b>Date:</b> 2007-06-30</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
One other small thing, in TR1 5.2.1.2 [tr.num.sf.Plm], the restriction should&nbsp;&nbsp;be
<tt>|x| &lt;= 1</tt>, not <tt>x &gt;= 0</tt>.</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="703"></a>703. <tt>map::at()</tt> need a complexity specification</h3>
<p><b>Section:</b> 23.3.1.2 [map.access] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Joe Gottman <b>Date:</b> 2007-07-03</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#map.access">issues</a> in [map.access].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<tt>map::at()</tt> need a complexity specification.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add the following to the specification of <tt>map::at()</tt>, 23.3.1.2 [map.access]:
</p>
<blockquote>
<p>
<i>Complexity:</i> logarithmic.
</p>
</blockquote>





<hr>
<h3><a name="704"></a>704. MoveAssignable requirement for container value type overly strict</h3>
<p><b>Section:</b> 23.1 [container.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-05-20</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#container.requirements">active issues</a> in [container.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#container.requirements">issues</a> in [container.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The move-related changes inadvertently overwrote the intent of <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#276">276</a>.
Issue <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#276">276</a> removed the requirement of <tt>CopyAssignable</tt> from
most of the member functions of node-based containers.  But the move-related changes
unnecessarily introduced the <tt>MoveAssignable</tt> requirement for those members which used to
require <tt>CopyAssignable</tt>.
</p>

<p>
We also discussed (c++std-lib-18722) the possibility of dropping <tt>MoveAssignable</tt>
from some of the sequence requirements.  Additionally the <i>in-place</i> construction
work may further reduce requirements.  For purposes of an easy reference, here are the
minimum sequence requirements as I currently understand them.  Those items in requirements
table in the working draft which do not appear below have been purposefully omitted for
brevity as they do not have any requirements of this nature.  Some items which do not
have any requirements of this nature are included below just to confirm that they were
not omitted by mistake.
</p>

<table border="1">
<caption>Container Requirements</caption>
<tbody><tr><td><tt>X u(a)</tt></td><td><tt>value_type</tt> must be <tt>CopyConstructible</tt></td></tr>
<tr><td><tt>X u(rv)</tt></td><td><tt>array</tt> requires <tt>value_type</tt> to be <tt>MoveConstructible</tt></td></tr>
<tr><td><tt>a = u</tt></td><td>Sequences require <tt>value_type</tt> to be <tt>CopyConstructible</tt> and <tt>CopyAssignable</tt>.
                               Associative containers require <tt>value_type</tt> to be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a = rv</tt></td><td><tt>array</tt> requires <tt>value_type</tt> to be <tt>MoveAssignable</tt>.
                                Sequences with non-<tt>Swappable</tt> allocators require <tt>value_type</tt> to be <tt>MoveConstructible</tt> and <tt>MoveAssignable</tt>.
                                Associative containers with non-<tt>Swappable</tt> allocators require <tt>value_type</tt> to be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>swap(a,u)</tt></td><td><tt>array</tt> requires <tt>value_type</tt> to be <tt>Swappable</tt>.
                                Sequences with non-<tt>Swappable</tt> allocators require <tt>value_type</tt> to be <tt>Swappable</tt>, <tt>MoveConstructible</tt> and <tt>MoveAssignable</tt>.
                                Associative containers with non-<tt>Swappable</tt> allocators require <tt>value_type</tt> to be <tt>MoveConstructible</tt>.</td></tr>
</tbody></table>

<p>
</p>

<table border="1">
<caption>Sequence Requirements</caption>
<tbody><tr><td><tt>X(n)</tt></td><td><tt>value_type</tt> must be <tt>DefaultConstructible</tt></td></tr>
<tr><td><tt>X(n, t)</tt></td><td><tt>value_type</tt> must be <tt>CopyConstructible</tt></td></tr>
<tr><td><tt>X(i, j)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                 If the iterators return an rvalue the <tt>value_type</tt> must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(p, t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                        The sequences <tt>vector</tt> and <tt>deque</tt> also require the <tt>value_type</tt> to be <tt>CopyAssignable</tt>.</td></tr>
<tr><td><tt>a.insert(p, rv)</tt></td><td>The <tt>value_type</tt> must be <tt>MoveConstructible</tt>.
                                        The sequences <tt>vector</tt> and <tt>deque</tt> also require the <tt>value_type</tt> to be <tt>MoveAssignable</tt>.</td></tr>
<tr><td><tt>a.insert(p, n, t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                        The sequences <tt>vector</tt> and <tt>deque</tt> also require the <tt>value_type</tt> to be <tt>CopyAssignable</tt>.</td></tr>
<tr><td><tt>a.insert(p, i, j)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                        The sequences <tt>vector</tt> and <tt>deque</tt> also require the <tt>value_type</tt> to be <tt>CopyAssignable</tt> when the iterators return an lvalue.
                                        If the iterators return an rvalue the <tt>value_type</tt> must be <tt>MoveConstructible</tt>.
                                        The sequences <tt>vector</tt> and <tt>deque</tt> also require the <tt>value_type</tt> to be <tt>MoveAssignable</tt> when the iterators return an rvalue.</td></tr>
<tr><td><tt>a.erase(p)</tt></td><td>The sequences <tt>vector</tt> and <tt>deque</tt> require the <tt>value_type</tt> to be <tt>MoveAssignable</tt>.</td></tr>
<tr><td><tt>a.erase(q1, q2)</tt></td><td>The sequences <tt>vector</tt> and <tt>deque</tt> require the <tt>value_type</tt> to be <tt>MoveAssignable</tt>.</td></tr>
<tr><td><tt>a.clear()</tt></td><td></td></tr>
<tr><td><tt>a.assign(i, j)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt> and <tt>CopyAssignable</tt>.
                                        If the iterators return an rvalue the <tt>value_type</tt> must be <tt>MoveConstructible</tt> and <tt>MoveAssignable</tt>.</td></tr>
<tr><td><tt>a.assign(n, t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt> and <tt>CopyAssignable</tt>.</td></tr>
<tr><td><tt>a.resize(n)</tt></td><td>The <tt>value_type</tt> must be <tt>DefaultConstructible</tt>.
                                     The sequences <tt>vector</tt> and <tt>deque</tt> also require the <tt>value_type</tt> to be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.resize(n, t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
</tbody></table>

<p>
</p>

<table border="1">
<caption>Optional Sequence Requirements</caption>
<tbody><tr><td><tt>a.front()</tt></td><td></td></tr>
<tr><td><tt>a.back()</tt></td><td></td></tr>
<tr><td><tt>a.push_front(t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a.push_front(rv)</tt></td><td>The <tt>value_type</tt> must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.push_back(t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a.push_back(rv)</tt></td><td>The <tt>value_type</tt> must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.pop_front()</tt></td><td></td></tr>
<tr><td><tt>a.pop_back()</tt></td><td></td></tr>
<tr><td><tt>a[n]</tt></td><td></td></tr>
<tr><td><tt>a.at[n]</tt></td><td></td></tr>
</tbody></table>

<p>
</p>

<table border="1">
<caption>Associative Container Requirements</caption>
<tbody><tr><td><tt>X(i, j)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                 If the iterators return an rvalue the <tt>value_type</tt> must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a_uniq.insert(t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a_uniq.insert(rv)</tt></td><td>The <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a_eq.insert(t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a_eq.insert(rv)</tt></td><td>The <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(p, t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(p, rv)</tt></td><td>The <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(i, j)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                        If the iterators return an rvalue the <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>..</td></tr>
</tbody></table>

<p>
</p>

<table border="1">
<caption>Unordered Associative Container Requirements</caption>
<tbody><tr><td><tt>X(i, j, n, hf, eq)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                 If the iterators return an rvalue the <tt>value_type</tt> must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a_uniq.insert(t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a_uniq.insert(rv)</tt></td><td>The <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a_eq.insert(t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a_eq.insert(rv)</tt></td><td>The <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(p, t)</tt></td><td>The <tt>value_type</tt> must be <tt>CopyConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(p, rv)</tt></td><td>The <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>a.insert(i, j)</tt></td><td>If the iterators return an lvalue the <tt>value_type</tt> must be <tt>CopyConstructible</tt>.
                                        If the iterators return an rvalue the <tt>key_type</tt> and the <tt>mapped_type</tt> (if it exists) must be <tt>MoveConstructible</tt>..</td></tr>
</tbody></table>

<p>
</p>

<table border="1">
<caption>Miscellaneous Requirements</caption>
<tbody><tr><td><tt>map[lvalue-key]</tt></td><td>The <tt>key_type</tt> must be <tt>CopyConstructible</tt>.
                                         The <tt>mapped_type</tt> must be <tt>DefaultConstructible</tt> and <tt>MoveConstructible</tt>.</td></tr>
<tr><td><tt>map[rvalue-key]</tt></td><td>The <tt>key_type</tt> must be <tt>MoveConstructible</tt>.
                                         The <tt>mapped_type</tt> must be <tt>DefaultConstructible</tt> and <tt>MoveConstructible</tt>.</td></tr>
</tbody></table>

<p><i>[
Kona (2007): Howard and Alan to update requirements table in issue with emplace signatures.
]</i></p>




<p><b>Proposed resolution:</b></p>






<hr>
<h3><a name="705"></a>705. type-trait <tt>decay</tt> incompletely specified</h3>
<p><b>Section:</b> 20.4.7 [meta.trans.other] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Thorsten Ottosen <b>Date:</b> 2007-07-08</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The current working draft has a type-trait <tt>decay</tt> in 20.4.7 [meta.trans.other].
</p>

<p>
Its use is to turn C++03 pass-by-value parameters into efficient C++0x
pass-by-rvalue-reference parameters. However, the current definition
introduces an incompatible change where the cv-qualification of the
parameter type is retained. The deduced type should loose such
cv-qualification, as pass-by-value does.
</p>


<p><b>Proposed resolution:</b></p>
<p>
In 20.4.7 [meta.trans.other] change the last sentence:
</p>

<blockquote><p>
Otherwise the  member typedef <tt>type</tt> equals <tt><ins>remove_cv&lt;</ins>U<ins>&gt;::type</ins></tt>.
</p></blockquote>

<p>
In 20.3.1.2 [tuple.creation]/1 change:
</p>

<blockquote><p>
<del>where each <tt>Vi</tt> in <tt>VTypes</tt> is <tt>X&amp;</tt> if, for the
corresponding type <tt>Ti</tt> in <tt>Types</tt>,
<tt>remove_cv&lt;remove_reference&lt;Ti&gt;::type&gt;::type</tt> equals
<tt>reference_wrapper&lt;X&gt;</tt>, otherwise <tt>Vi</tt> is
<tt>decay&lt;Ti&gt;::type</tt>.</del>
<ins>Let <tt>Ui</tt> be <tt>decay&lt;Ti&gt;::type</tt> for each
<tt>Ti</tt> in <tt>Types</tt>. Then each <tt>Vi</tt> in <tt>VTypes</tt>
is <tt>X&amp;</tt> if <tt>Ui</tt> equals
<tt>reference_wrapper&lt;X&gt;</tt>, otherwise <tt>Vi</tt> is
<tt>Ui</tt>.</ins>
</p></blockquote>






<hr>
<h3><a name="706"></a>706. <tt>make_pair()</tt> should behave as <tt>make_tuple()</tt> wrt. <tt>reference_wrapper()</tt></h3>
<p><b>Section:</b> 20.2.3 [pairs] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Ready">Ready</a>
 <b>Submitter:</b> Thorsten Ottosen <b>Date:</b> 2007-07-08</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#pairs">issues</a> in [pairs].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Ready">Ready</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The current draft has <tt>make_pair()</tt> in 20.2.3 [pairs]/16
and <tt>make_tuple()</tt> in 20.3.1.2 [tuple.creation].
<tt>make_tuple()</tt> detects the presence of
<tt>reference_wrapper&lt;X&gt;</tt> arguments and "unwraps" the reference in
such cases. <tt>make_pair()</tt> would OTOH create a
<tt>reference_wrapper&lt;X&gt;</tt> member. I suggest that the two
functions are made to behave similar in this respect to minimize
confusion.
</p>


<p><b>Proposed resolution:</b></p>
<p>
In 20.2 [utility] change the synopsis for make_pair() to read
</p>

<blockquote><pre>template &lt;class T1, class T2&gt;
  pair&lt;<del>typename decay&lt;T1&gt;::type</del> <ins>V1</ins>, <del>typename decay&lt;T2&gt;::type</del> <ins>V2</ins>&gt; make_pair(T1&amp;&amp;, T2&amp;&amp;);
</pre></blockquote>

<p>
In 20.2.3 [pairs]/16 change the declaration to match the above synopsis.
Then change the 20.2.3 [pairs]/17 to:
</p>

<blockquote>
<p>
<i>Returns:</i> <tt>pair&lt;<del>typename decay&lt;T1&gt;::type</del> <ins>V1</ins>,<del>typename decay&lt;T2&gt;::type</del> <ins>V2</ins>&gt;(forward&lt;T1&gt;(x),forward&lt;T2&gt;(y))</tt> <ins>where <tt>V1</tt> and
<tt>V2</tt> are determined as follows: Let <tt>Ui</tt> be
<tt>decay&lt;Ti&gt;::type</tt> for each <tt>Ti</tt>. Then each
<tt>Vi</tt> is <tt>X&amp;</tt> if <tt>Ui</tt> equals
<tt>reference_wrapper&lt;X&gt;</tt>, otherwise <tt>Vi</tt> is
<tt>Ui</tt>.</ins>
</p>
</blockquote>






<hr>
<h3><a name="707"></a>707. null pointer constant for <tt>exception_ptr</tt></h3>
<p><b>Section:</b> 18.7.1 [exception] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Jens Maurer <b>Date:</b> 2007-07-20</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>

<p>
From the Toronto Core wiki:
</p>

<p>
What do you mean by "null pointer constant"? How do you guarantee that
<tt>exception_ptr() == 1</tt> doesn't work? &nbsp;Do you even want to prevent that?
What's the semantics? &nbsp;What about <tt>void *p = 0; exception_ptr() == p</tt>?
Maybe disallow those in the interface, but how do you do that with
portable C++? Could specify just "make it work".
</p>

<p>
Peter's response:
</p>

<p>
null pointer constant as defined in 4.10 [conv.ptr]. Intent is "just make it
work", can be implemented as assignment operator taking a unique pointer
to member, as in the unspecified bool type idiom.
</p>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="708"></a>708. Locales need to be per thread and updated for POSIX changes</h3>
<p><b>Section:</b> 22 [localization] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#Open">Open</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-07-28</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#localization">issues</a> in [localization].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#Open">Open</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The POSIX "Extended API Set Part 4,"
</p>
<blockquote><p>
<a href="http://www.opengroup.org/sib/details.tpl?id=C065">http://www.opengroup.org/sib/details.tpl?id=C065</a>
</p></blockquote>
<p>
introduces extensions to the C locale mechanism that
allow multiple concurrent locales to be used in the same application
by introducing a type <tt>locale_t</tt> that is very similar to
<tt>std::locale</tt>, and a number of <tt>_l</tt> functions that make use of it.
</p>
<p>
The global locale (set by setlocale) is now specified to be per-
process. If a thread does not call <tt>uselocale</tt>, the global locale is
in effect for that thread. It can install a per-thread locale by
using <tt>uselocale</tt>.
</p>
<p>
There is also a nice <tt>querylocale</tt> mechanism by which one can obtain
the name (such as "de_DE") for a specific <tt>facet</tt>, even for combined
locales, with no <tt>std::locale</tt> equivalent.
</p>
<p>
<tt>std::locale</tt> should be harmonized with the new POSIX <tt>locale_t</tt>
mechanism and provide equivalents for <tt>uselocale</tt> and <tt>querylocale</tt>.
</p>

<p><i>[
Kona (2007): Bill and Nick to provide wording.
]</i></p>




<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="709"></a>709. <tt>char_traits::not_eof</tt> has wrong signature</h3>
<p><b>Section:</b> 21.1.3 [char.traits.specializations] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Bo Persson <b>Date:</b> 2007-08-13</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The changes made for <tt>constexpr</tt> in 21.1.3 [char.traits.specializations] have 
not only changed the <tt>not_eof</tt> function from pass by const reference to 
pass by value, it has also changed the parameter type from <tt>int_type</tt> to 
<tt>char_type</tt>.
</p>
<p>
This doesn't work for type <tt>char</tt>, and is inconsistent with the 
requirements in Table 56, Traits requirements, 21.1.1 [char.traits.require].
</p>

<p>
Pete adds:
</p>

<blockquote><p>
For what it's worth, that may not have been an intentional change. 
N2349, which detailed the changes for adding constant expressions to 
the library, has strikeout bars through the <tt>const</tt> and the <tt>&amp;</tt> that 
surround the <tt>char_type</tt> argument, but none through <tt>char_type</tt> itself. 
So the intention may have been just to change to pass by value, with 
text incorrectly copied from the standard.
</p></blockquote>



<p><b>Proposed resolution:</b></p>
<p>
Change the signature in 21.1.3.1 [char.traits.specializations.char],
21.1.3.2 [char.traits.specializations.char16_t], 21.1.3.3 [char.traits.specializations.char32_t],
and 21.1.3.4 [char.traits.specializations.wchar.t] to
</p>

<blockquote><pre>static constexpr int_type not_eof(<del>char_type</del> <ins>int_type</ins> c);
</pre></blockquote>






<hr>
<h3><a name="710"></a>710. Missing postconditions</h3>
<p><b>Section:</b> 20.6.6.2 [util.smartptr.shared] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-08-24</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#util.smartptr.shared">active issues</a> in [util.smartptr.shared].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#util.smartptr.shared">issues</a> in [util.smartptr.shared].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
A discussion on
<a href="http://groups.google.com/group/comp.std.c++/browse_frm/thread/8e89dceb35cd7971">comp.std.c++</a>
has identified a contradiction in the <tt>shared_ptr</tt> specification.
The <tt>shared_ptr</tt> move constructor and the cast functions are
missing postconditions for the <tt>get()</tt> accessor.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Add to 20.6.6.2.1 [util.smartptr.shared.const]:
</p>

<blockquote>
<pre>shared_ptr(shared_ptr&amp;&amp; r);
template&lt;class Y&gt; shared_ptr(shared_ptr&lt;Y&gt;&amp;&amp; r);
</pre>
<blockquote>
<p>
<i>Postconditions:</i>  <tt>*this</tt> shall contain the old value of <tt>r</tt>. <tt>r</tt>
shall be empty. <ins><tt>r.get() == 0</tt>.</ins>
</p>
</blockquote>
</blockquote>

<p>
Add to 20.6.6.2.10 [util.smartptr.shared.cast]:
</p>

<blockquote>
<pre>template&lt;class T, class U&gt; shared_ptr&lt;T&gt; static_pointer_cast(shared_ptr&lt;U&gt; const&amp; r);
</pre>
<blockquote>
<p>
<ins><i>Postconditions:</i> If <tt>w</tt> is the return value,
<tt>w.get() == static_cast&lt;T*&gt;(r.get()) &amp;&amp; w.use_count() == r.use_count()</tt>.</ins>
</p>
</blockquote>
</blockquote>

<blockquote>
<pre>template&lt;class T, class U&gt; shared_ptr&lt;T&gt; dynamic_pointer_cast(shared_ptr&lt;U&gt; const&amp; r);
</pre>
<blockquote>
<p>
<ins><i>Postconditions:</i> If <tt>w</tt> is the return value, <tt>w.get() == dynamic_cast&lt;T*&gt;(r.get())</tt>.</ins>
</p>
</blockquote>
</blockquote>

<blockquote>
<pre>template&lt;class T, class U&gt; shared_ptr&lt;T&gt; const_pointer_cast(shared_ptr&lt;U&gt; const&amp; r);
</pre>
<blockquote>
<p>
<ins><i>Postconditions:</i> If <tt>w</tt> is the return value,
<tt>w.get() == const_cast&lt;T*&gt;(r.get()) &amp;&amp; w.use_count() == r.use_count()</tt>.</ins>
</p>
</blockquote>
</blockquote>

<p>
Alberto Ganesh Barbati has written an
<a href="http://barbati.net/c++/shared_ptr.pdf">alternative proposal</a>
where he suggests (among other things) that the casts be respecified in terms of
the aliasing constructor as follows:
</p>

<p>
Change 20.6.6.2.10 [util.smartptr.shared.cast]:
</p>

<blockquote>
<p>
-2- <i>Returns:</i> <del>If <tt>r</tt> is empty, an <tt>empty
shared_ptr&lt;T&gt;;</tt> otherwise, a <tt>shared_ptr&lt;T&gt;</tt>
object that stores <tt>static_cast&lt;T*&gt;(r.get())</tt> and shares ownership with
<tt>r</tt>.</del> <ins><tt>shared_ptr&lt;T&gt;(r, static_cast&lt;T*&gt;(r.get())</tt>.</ins>
</p>
</blockquote>

<blockquote>
<p>
-6- <i>Returns:</i>
</p>
<ul>
<li><del>When <tt>dynamic_cast&lt;T*&gt;(r.get())</tt> returns a nonzero value,
a <tt>shared_ptr&lt;T&gt;</tt> object that stores a copy 
of it and <i>shares ownership</i> with <tt>r</tt>;</del></li>
<li><del>Otherwise, an <i>empty</i> <tt>shared_ptr&lt;T&gt;</tt> object.</del></li>
<li><ins>If <tt>p = dynamic_cast&lt;T*&gt;(r.get())</tt> is a non-null pointer, <tt>shared_ptr&lt;T&gt;(r, p);</tt></ins></li>
<li><ins>Otherwise, <tt>shared_ptr&lt;T&gt;()</tt>.</ins></li>
</ul>
</blockquote>

<blockquote>
<p>
-10- <i>Returns:</i> <del>If <tt>r</tt> is empty, an <tt>empty
shared_ptr&lt;T&gt;;</tt> otherwise, a <tt>shared_ptr&lt;T&gt;</tt>
object that stores <tt>const_cast&lt;T*&gt;(r.get())</tt> and shares ownership with
<tt>r</tt>.</del> <ins><tt>shared_ptr&lt;T&gt;(r, const_cast&lt;T*&gt;(r.get())</tt>.</ins>
</p>
</blockquote>

<p>
This takes care of the missing postconditions for the casts by bringing
in the aliasing constructor postcondition "by reference".
</p>






<hr>
<h3><a name="711"></a>711. Contradiction in empty <tt>shared_ptr</tt></h3>
<p><b>Section:</b> 20.6.6.2.5 [util.smartptr.shared.obs] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Peter Dimov <b>Date:</b> 2007-08-24</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#util.smartptr.shared.obs">issues</a> in [util.smartptr.shared.obs].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
A discussion on
<a href="http://groups.google.com/group/comp.std.c++/browse_frm/thread/8e89dceb35cd7971">comp.std.c++</a>
has identified a contradiction in the <tt>shared_ptr</tt> specification.
The note:
</p>

<blockquote><p>
[ <i>Note:</i> this constructor allows creation of an empty shared_ptr instance with a non-NULL stored pointer.
-end note ]
</p></blockquote>

<p>
after the aliasing constructor
</p>

<blockquote><pre>template&lt;class Y&gt; shared_ptr(shared_ptr&lt;Y&gt; const&amp; r, T *p);
</pre></blockquote>

<p>
reflects the intent of
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2351.htm">N2351</a>
to, well, allow the creation of an empty <tt>shared_ptr</tt>
with a non-NULL stored pointer.
</p>

<p>
This is contradicted by the second sentence in the Returns clause of 20.6.6.2.5 [util.smartptr.shared.obs]:
</p>

<blockquote>
<pre>T* get() const;
</pre>
<blockquote><p>
<i>Returns:</i> the stored pointer. Returns a null pointer if <tt>*this</tt> is empty.
</p></blockquote>
</blockquote>



<p><b>Proposed resolution:</b></p>
<p>
In keeping the N2351 spirit and obviously my preference, change 20.6.6.2.5 [util.smartptr.shared.obs]:
</p>

<blockquote>
<pre>T* get() const;
</pre>
<blockquote><p>
<i>Returns:</i> the stored pointer. <del>Returns a null pointer if <tt>*this</tt> is empty.</del>
</p></blockquote>
</blockquote>

<p>
Alternative proposed resolution: (I won't be happy if we do this, but it's possible):
</p>

<p>
Change 20.6.6.2.1 [util.smartptr.shared.const]:
</p>

<blockquote>
<pre>template&lt;class Y&gt; shared_ptr(shared_ptr&lt;Y&gt; const&amp; r, T *p);
</pre>
<blockquote>
<p>
<ins><i>Requires:</i> If <tt>r</tt> is empty, <tt>p</tt> shall be <tt>0</tt>.</ins>
</p>
<p>
<del>[ <i>Note:</i> this constructor allows creation of an empty <tt>shared_ptr</tt>
instance with a non-NULL stored pointer. 
-- <i>end note</i> ]</del>
</p>
</blockquote>
</blockquote>






<hr>
<h3><a name="713"></a>713. <tt>sort()</tt> complexity is too lax</h3>
<p><b>Section:</b> 25.3.1.1 [sort] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Matt Austern <b>Date:</b> 2007-08-30</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The complexity of <tt>sort()</tt> is specified as "Approximately <tt>N
log(N)</tt> (where <tt>N == last - first</tt> ) comparisons on the
average", with no worst case complicity specified. The intention was to
allow a median-of-three quicksort implementation, which is usually <tt>O(N
log N)</tt> but can be quadratic for pathological inputs. However, there is
no longer any reason to allow implementers the freedom to have a
worst-cast-quadratic sort algorithm. Implementers who want to use
quicksort can use a variant like David Musser's "Introsort" (Software
Practice and Experience 27:983-993, 1997), which is guaranteed to be <tt>O(N
log N)</tt> in the worst case without incurring additional overhead in the
average case. Most C++ library implementers already do this, and there
is no reason not to guarantee it in the standard.
</p>


<p><b>Proposed resolution:</b></p>
<p>
In 25.3.1.1 [sort], change the complexity to "O(N log N)", and remove footnote 266:
</p>

<blockquote>
<p>
<i>Complexity:</i> <del>Approximately</del> <ins>O(</ins><i>N</i> log(<i>N</i>)<ins>)</ins> <del>(where <i>N</i> == <i>last</i> - <i>first</i> )
</del>comparisons<del> on the average</del>.<del><sup>266)</sup></del>
</p>
<p>
<del><sup>266)</sup>
If the worst case behavior is important <tt>stable_sort()</tt> (25.3.1.2) or <tt>partial_sort()</tt>
(25.3.1.3) should be used.</del>
</p>
</blockquote>






<hr>
<h3><a name="714"></a>714. <tt>search_n</tt> complexity is too lax</h3>
<p><b>Section:</b> 25.1.9 [alg.search] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Matt Austern <b>Date:</b> 2007-08-30</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#alg.search">issues</a> in [alg.search].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The complexity for <tt>search_n</tt> (25.1.9 [alg.search] par 7) is specified as "At most
(last - first ) * count applications of the corresponding predicate if
count is positive, or 0 otherwise." This is unnecessarily pessimistic.
Regardless of the value of count, there is no reason to examine any
element in the range more than once.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change the complexity to "At most (last - first) applications of the corresponding predicate".
</p>

<blockquote>
<pre>template&lt;class ForwardIterator, class Size, class T&gt; 
  ForwardIterator 
    search_n(ForwardIterator first , ForwardIterator last , Size count , 
             const T&amp; value ); 

template&lt;class ForwardIterator, class Size, class T, 
         class BinaryPredicate&gt; 
  ForwardIterator 
    search_n(ForwardIterator first , ForwardIterator last , Size count , 
             const T&amp; value , BinaryPredicate pred );
</pre>
<blockquote>
<p>
<i>Complexity:</i> At most <tt>(last - first ) <del>* count</del></tt> applications of the corresponding predicate
<del>if <tt>count</tt> is positive, or 0 otherwise</del>.
</p>
</blockquote>
</blockquote>






<hr>
<h3><a name="715"></a>715. <tt>minmax_element</tt> complexity is too lax</h3>
<p><b>Section:</b> 25.3.7 [alg.min.max] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Matt Austern <b>Date:</b> 2007-08-30</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#alg.min.max">issues</a> in [alg.min.max].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The complexity for <tt>minmax_element</tt> (25.3.7 [alg.min.max] par 16) says "At most <tt>max(2 *
(last - first ) - 2, 0)</tt> applications of the corresponding comparisons",
i.e. the worst case complexity is no better than calling <tt>min_element</tt> and
<tt>max_element</tt> separately. This is gratuitously inefficient. There is a
well known technique that does better: see section 9.1 of CLRS
(Introduction to Algorithms, by Cormen, Leiserson, Rivest, and Stein).
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 25.3.7 [alg.min.max] to:
</p>

<blockquote>
<pre>template&lt;class ForwardIterator&gt; 
  pair&lt;ForwardIterator, ForwardIterator&gt; 
    minmax_element(ForwardIterator first , ForwardIterator last); 
template&lt;class ForwardIterator, class Compare&gt; 
  pair&lt;ForwardIterator, ForwardIterator&gt; 
    minmax_element(ForwardIterator first , ForwardIterator last , Compare comp);
</pre>
<blockquote>
<p>
<i>Returns:</i> <tt>make_pair(m, M)</tt>, where <tt>m</tt> is
<del><tt>min_element(first, last)</tt> or <tt>min_element(first, last,
comp)</tt></del> <ins>the first iterator <tt>i</tt> in <tt>[first,
last)</tt> such that no other element in the range is smaller,</ins> and
<ins>where</ins> <tt>M</tt> is <del><tt>max_element(first, last)</tt> or
<tt>max_element(first, last, comp)</tt></del> <ins>the last iterator
<tt>i</tt> in <tt>[first, last)</tt> such that no other element in the
range is larger</ins>.
</p>
<p>
<i>Complexity:</i> At most <del><tt>max(2 * (last - first ) - 2, 0)</tt></del>
<ins><tt>max(&#8970;(3/2) (N-1)&#8971;, 0)</tt></ins> applications of the
corresponding <del>comparisons</del> <ins>predicate, where <tt>N</tt> is <tt>distance(first, last)</tt></ins>.
</p>
</blockquote>
</blockquote>






<hr>
<h3><a name="716"></a>716. Production in [re.grammar] not actually modified</h3>
<p><b>Section:</b> 28.13 [re.grammar] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan T. Lavavej <b>Date:</b> 2007-08-31</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
TR1 7.13 [tr.re.grammar]/3 and C++0x WP 28.13 [re.grammar]/3 say:
</p>

<blockquote>
<p>
The following productions within the ECMAScript grammar are modified as follows:
</p>

<blockquote><pre>CharacterClass ::
[ [lookahead &#8713; {^}] ClassRanges ]
[ ^ ClassRanges ]
</pre></blockquote>

</blockquote>

<p>
This definition for <tt>CharacterClass</tt> appears to be exactly identical to that in ECMA-262.
</p>

<p>
Was an actual modification intended here and accidentally omitted, or was this production accidentally included?
</p>


<p><b>Proposed resolution:</b></p>
<p>
Remove this mention of the CharacterClass production.
</p>

<blockquote><pre><del>CharacterClass ::
[ [lookahead &#8713; {^}] ClassRanges ]
[ ^ ClassRanges ]</del>
</pre></blockquote>






<hr>
<h3><a name="717"></a>717. Incomplete <tt>valarray::operator[]</tt> specification in [valarray.access]</h3>
<p><b>Section:</b> 26.5.2.3 [valarray.access] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-08-27</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#valarray.access">issues</a> in [valarray.access].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Since the return type of <tt>valarray</tt>'s <tt>operator[] const</tt> overload has been
changed to <tt>const T&amp;</tt> as described in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#389">389</a> several paragraphs of
the section 26.5.2.3 [valarray.access] are now
incompletely
specified, because many requirements and guarantees should now also
apply to the const overload. Most notably, the address and reference
guarantees should be extended to the const overload case.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 26.5.2.3 [valarray.access]:
</p>

<blockquote>
<p>
-1- <del>When applied to a constant array, the subscript operator returns a
reference to the corresponding element of the array. When applied to a
non-constant array, t</del><ins>T</ins>he subscript operator returns a
reference to the corresponding element of the array.
</p>

<p>
-3- The expression <tt>&amp;a[i+j] == &amp;a[i] + j</tt> evaluates as <tt>true</tt> for all <tt>size_t i</tt>
and <tt>size_t j</tt> such that <tt>i+j</tt> is less 
than the length of the <del>non-constant</del> array <tt>a</tt>.
</p>

<p>
-4- Likewise, the expression <tt>&amp;a[i] != &amp;b[j]</tt> evaluates
as <tt>true</tt> for any two <del>non-constant</del> arrays <tt>a</tt> and
<tt>b</tt> and for any <tt>size_t i</tt> and <tt>size_t j</tt> such that
<tt>i</tt> is less than the length of <tt>a</tt> and <tt>j</tt> is less
than the length of <tt>b</tt>. This property indicates an absence of
aliasing and may be used to advantage by optimizing
compilers.<sup>281)</sup>
</p>

<p>
-5- The reference returned by the subscript operator for a<ins>n</ins> <del>non-constant</del> array is guaranteed to be valid until
the member function <tt>resize(size_t, T)</tt> (26.5.2.7) is called for that array or until the lifetime 
of that array ends, whichever happens first.
</p>

</blockquote>






<hr>
<h3><a name="718"></a>718. <tt>basic_string</tt> is not a sequence</h3>
<p><b>Section:</b> 21.3 [basic.string] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Bo Persson <b>Date:</b> 2007-08-18</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#basic.string">active issues</a> in [basic.string].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#basic.string">issues</a> in [basic.string].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Paragraph 21.3 [basic.string]/3 states:
</p>

<blockquote>
<p>
The class template <tt>basic_string</tt> conforms to the requirements for a 
Sequence (23.1.1) and for a Reversible Container (23.1).
</p>
</blockquote>

<p>
First of all, 23.1.1 [sequence.reqmts] is no longer "Sequence" but "Sequence container". 
Secondly, after the resent changes to containers (<tt>emplace</tt>, <tt>push_back</tt>, 
<tt>const_iterator</tt> parameters to <tt>insert</tt> and <tt>erase</tt>), <tt>basic_string</tt> is not 
even close to conform to the current requirements.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Remove this sentence, in recognition of the fact that <tt>basic_string</tt> is 
not just a <tt>vector</tt>-light for literal types, but something quite 
different, a string abstraction in its own right.
</p>





<hr>
<h3><a name="719"></a>719. <tt>std::is_literal</tt> type traits should be provided</h3>
<p><b>Section:</b> 20.4 [meta] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-08-25</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#meta">issues</a> in [meta].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Since the inclusion of <tt>constexpr</tt> in the standard draft N2369 we have
a new type category "literal", which is defined in 3.9 [basic.types]/p.11:
</p>

<blockquote>
<p>
-11- A type is a <i>literal</i> type if it is:
</p>
<ul>
<li>a scalar type; or</li>
<li><p>a class type (clause 9) with</p>
<ul>
<li>a trivial copy constructor,</li>
<li>a trivial destructor,</li>
<li>at least one constexpr constructor other than the copy constructor,</li>
<li>no virtual base classes, and</li>
<li>all non-static data members and base classes of literal types; or</li>
</ul>
</li>
<li>an array of literal type.</li>
</ul>
</blockquote>

<p>
I strongly suggest that the standard provides a type traits for
literal types in 20.4.4.3 [meta.unary.prop] for several reasons:
</p>

<ol type="a">
<li>To keep the traits in sync with existing types.</li>
<li>I see many reasons for programmers to use this trait in template
   code to provide optimized template definitions for these types,
   see below.</li>
<li>A user-provided definition of this trait is practically impossible
to write portably.</li>
</ol>

<p>
The special problem of reason (c) is that I don't see currently a
way to portably test the condition for literal class types:
</p>

<blockquote>
<ul>
<li>at least one constexpr constructor other than the copy constructor,</li>
</ul>
</blockquote>

<p>
Here follows a simply example to demonstrate it's usefulness:
</p>

<blockquote><pre>template &lt;typename T&gt;
constexpr typename std::enable_if&lt;std::is_literal&lt;T&gt;::value, T&gt;::type
abs(T x) {
  return x &lt; T() ? -x : x;
}

template &lt;typename T&gt;
typename std::enable_if&lt;!std::is_literal&lt;T&gt;::value, T&gt;::type
abs(const T&amp; x) {
  return x &lt; T() ? -x : x;
}
</pre></blockquote>

<p>
Here we have the possibility to provide a general <tt>abs</tt> function
template that can be used in ICE's if it's argument is a literal
type which's value is a constant expression, otherwise we
have an optimized version for arguments which are expensive
to copy and therefore need the usage of arguments of
reference type (instead of <tt>const T&amp;</tt> we could decide to
use <tt>T&amp;&amp;</tt>, but that is another issue).
</p>



<p><b>Proposed resolution:</b></p>
<p>
In 20.4.2 [meta.type.synop] in the group "type properties",
just below the line
</p>

<blockquote><pre>template &lt;class T&gt; struct is_pod;
</pre></blockquote>

<p>
add a new one:
</p>

<blockquote><pre>template &lt;class T&gt; struct is_literal;
</pre></blockquote>

<p>
In 20.4.4.3 [meta.unary.prop], table Type Property Predicates, just
below the line for the <tt>is_pod</tt> property add a new line:
</p>

<table border="1">
<tbody><tr>
<th>Template</th><th>Condition</th><th>Preconditions</th>
</tr>
<tr>
<td><tt>template &lt;class T&gt; struct is_literal;</tt></td>
<td><tt>T</tt> is a literal type (3.9)</td>
<td><tt>T</tt> shall be a complete type, an
array of unknown bound, or
(possibly cv-qualified) <tt>void</tt>.</td>
</tr>
</tbody></table>






<hr>
<h3><a name="720"></a>720. Omissions in constexpr usages</h3>
<p><b>Section:</b> 23.2.1 [array], 23.3.5 [template.bitset] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-08-25</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#array">active issues</a> in [array].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#array">issues</a> in [array].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<ol>
<li>
The member function <tt>bool array&lt;T,N&gt;::empty() const</tt> should be a
<tt>constexpr</tt> because this is easily to proof and to implement following it's operational
semantics defined by Table 87 (Container requirements) which says: <tt>a.size() == 0</tt>.
</li>
<li>
The member function <tt>bool bitset&lt;N&gt;::test() const</tt> must be a
<tt>constexpr</tt> (otherwise it would violate the specification of <tt>constexpr
bitset&lt;N&gt;::operator[](size_t) const</tt>, because it's return clause delegates to <tt>test()</tt>).
</li>
<li>
I wonder how the constructor <tt>bitset&lt;N&gt;::bitset(unsigned long)</tt> can
be declared as a <tt>constexpr</tt>. Current implementations usually have no such <tt>bitset</tt>
c'tor which would fulfill the requirements of a <tt>constexpr</tt> c'tor because they have a
non-empty c'tor body that typically contains for-loops or <tt>memcpy</tt> to compute the
initialisation. What have I overlooked here?
</li>
</ol>


<p><b>Proposed resolution:</b></p>
<ol>
<li>
<p>In the class template definition of 23.2.1 [array]/p. 3 change</p>
<blockquote><pre><ins>constexpr</ins> bool empty() const;
</pre></blockquote>
</li>

<li>
<p>In the class template definition of 23.3.5 [template.bitset]/p. 1 change</p>
<blockquote><pre><ins>constexpr</ins> bool test(size_t pos ) const;
</pre></blockquote>

<p>
and in 23.3.5.2 [bitset.members] change
</p>

<blockquote><pre><ins>constexpr</ins> bool test(size_t pos ) const;
</pre></blockquote>

</li>
</ol>





<hr>
<h3><a name="721"></a>721. <tt>wstring_convert</tt> inconsistensies</h3>
<p><b>Section:</b> 22.1.3.2.2 [conversions.string] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Bo Persson <b>Date:</b> 2007-08-27</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Paragraph 3 says that the <tt>Codecvt</tt> template parameter shall meet the 
requirements of <tt>std::codecvt</tt>, even though <tt>std::codecvt</tt> itself cannot 
be used (because of a protected destructor).
</p>

<p>
How are we going to explain this code to beginning programmers?
</p>

<blockquote><pre>template&lt;class I, class E, class S&gt;
struct codecvt : std::codecvt&lt;I, E, S&gt;
{
    ~codecvt()
    { }
};

void main()
{
    std::wstring_convert&lt;codecvt&lt;wchar_t, char, std::mbstate_t&gt; &gt; compiles_ok;
    
    std::wstring_convert&lt;std::codecvt&lt;wchar_t, char, std::mbstate_t&gt; &gt;   not_ok;
}
</pre></blockquote>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="722"></a>722. Missing [c.math] functions <tt>nanf</tt> and <tt>nanl</tt></h3>
<p><b>Section:</b> 26.7 [c.math] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-08-27</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#c.math">active issues</a> in [c.math].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#c.math">issues</a> in [c.math].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In the listing of 26.7 [c.math], table 108: Header <tt>&lt;cmath&gt;</tt> synopsis I miss
the following C99 functions (from 7.12.11.2):
</p>

<blockquote><pre>float nanf(const char *tagp);
long double nanl(const char *tagp);
</pre></blockquote>

<p>
(Note: These functions cannot be overloaded and they are also not
listed anywhere else)
</p>


<p><b>Proposed resolution:</b></p>
<p>
In 26.7 [c.math], table 108, section "Functions", add <tt>nanf</tt> and <tt>nanl</tt>
just after the existing entry <tt>nan</tt>.
</p>





<hr>
<h3><a name="723"></a>723. <tt>basic_regex</tt> should be moveable</h3>
<p><b>Section:</b> 28.8 [re.regex] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-08-29</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#re.regex">issues</a> in [re.regex].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
According to the current state of the standard draft, the class
template <tt>basic_regex</tt>, as described in 28.8 [re.regex]/3, is
neither <tt>MoveConstructible</tt> nor <tt>MoveAssignable</tt>.
IMO it should be, because typical regex state machines tend
to have a rather large data quantum and I have seen several
use cases, where a factory function returns regex values,
which would take advantage of moveabilities.
</p>


<p><b>Proposed resolution:</b></p>
<ol type="a">
<li>
<p>
In the header <tt>&lt;regex&gt;</tt> synopsis 28.4 [re.syn], just below the function
template <tt>swap</tt> add two further overloads:
</p>
<blockquote><pre>template &lt;class charT, class traits&gt; 
  void swap(basic_regex&lt;charT, traits&gt;&amp; e1,  basic_regex&lt;charT, traits&gt;&amp; e2);
<ins>template &lt;class charT, class traits&gt;
  void swap(basic_regex&lt;charT, traits&gt;&amp;&amp; e1, basic_regex&lt;charT, traits&gt;&amp; e2);
template &lt;class charT, class traits&gt;
  void swap(basic_regex&lt;charT, traits&gt;&amp; e1,  basic_regex&lt;charT, traits&gt;&amp;&amp; e2);</ins>
</pre></blockquote>
<p>
In the class definition of <tt>basic_regex</tt>, just below 28.8 [re.regex]/3,
perform the following changes:
</p>
</li>

<li>
<p>Just after the copy c'tor:</p>
<blockquote><pre>basic_regex(basic_regex&amp;&amp;);
</pre></blockquote>
</li>

<li>
<p>Just after the copy-assignment op.:</p>
<blockquote><pre>basic_regex&amp; operator=(basic_regex&amp;&amp;);
</pre></blockquote>
</li>

<li>
<p>Just after the first <tt>assign</tt> overload insert:</p>
<blockquote><pre>basic_regex&amp; assign(basic_regex&amp;&amp; that);
</pre></blockquote>
</li>

<li>
<p>Change the current <tt>swap</tt> function to read:</p>
<blockquote><pre>void swap(basic_regex&amp;&amp;);
</pre></blockquote>
</li>

<li>
<p>In 28.8.2 [re.regex.construct], just below the copy c'tor add a
corresponding member definition of:</p>
<blockquote><pre>basic_regex(basic_regex&amp;&amp;);
</pre></blockquote>
</li>

<li>
<p>Also in 28.8.2 [re.regex.construct], just below the copy assignment
c'tor add a corresponding member definition of:</p>
<blockquote><pre>basic_regex&amp; operator=(basic_regex&amp;&amp;);
</pre></blockquote>
</li>

<li>
<p>In 28.8.3 [re.regex.assign], just below the first <tt>assign</tt> overload add
a corresponding member definition of:</p>
<blockquote><pre>basic_regex&amp; assign(basic_regex&amp;&amp; that);
</pre></blockquote>
</li>

<li>
<p>In 28.8.6 [re.regex.swap], change the signature of <tt>swap</tt> to
say:</p>
<blockquote><pre>void swap(basic_regex&amp;&amp; e);
</pre></blockquote>
</li>

<li>
<p>In 28.8.7.1 [re.regex.nmswap], just below the single binary <tt>swap</tt>
function, add the two missing overloads:</p>
<blockquote><pre>template &lt;class charT, class traits&gt;
  void swap(basic_regex&lt;charT, traits&gt;&amp;&amp; e1, basic_regex&lt;charT, traits&gt;&amp; e2);
template &lt;class charT, class traits&gt;
  void swap(basic_regex&lt;charT, traits&gt;&amp; e1, basic_regex&lt;charT, traits&gt;&amp;&amp; e2);
</pre></blockquote>
</li>
</ol>

<p>
Of course there would be need of corresponding proper standardese
to describe these additions.
</p>






<hr>
<h3><a name="724"></a>724. <tt>DefaultConstructible</tt> is not defined</h3>
<p><b>Section:</b> 20.1.1 [utility.arg.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Pablo Halpern <b>Date:</b> 2007-09-12</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#utility.arg.requirements">active issues</a> in [utility.arg.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#utility.arg.requirements">issues</a> in [utility.arg.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The <tt>DefaultConstructible</tt> requirement is referenced in
several places in the August 2007 working draft
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2369.pdf">N2369</a>,
but is not defined anywhere.
</p>


<p><b>Proposed resolution:</b></p>
<p>
In section 20.1.1 [utility.arg.requirements], before table 33, add the
following table:
</p>

<p style="text-align: center;" align="center">Table 33: <tt>DefaultConstructible</tt> requirements</p>

<div align="center">

<table style="border-collapse: collapse;" border="0" cellpadding="0" cellspacing="0">
 <tbody><tr>
  <td style="border-style: solid none double solid; border-color: navy -moz-use-text-color navy navy; border-width: 1pt medium 1.5pt 1pt; padding: 0in 5.4pt; width: 85.5pt;" valign="top" width="114">
  <p style="margin: 0in 0in 0.0001pt; text-align: center;" align="center">expression</p>
  </td>
  <td style="border-style: solid solid double none; border-color: navy navy navy -moz-use-text-color; border-width: 1pt 1pt 1.5pt medium; padding: 0in 5.4pt; width: 243pt;" valign="top" width="324">
  <p style="margin: 0in 0in 0.0001pt; text-align: center;" align="center">post-condition</p>
  </td>
 </tr>
 <tr>
  <td style="border-style: none none solid solid; border-color: -moz-use-text-color -moz-use-text-color navy navy; border-width: medium medium 1pt 1pt; padding: 0in 5.4pt; width: 85.5pt;" valign="top" width="114">
  <p style="margin: 0in 0in 0.0001pt;"><tt>T
  t;</tt><br>
  <tt>T()</tt></p>
  </td>
  <td style="border-style: none solid solid none; border-color: -moz-use-text-color navy navy -moz-use-text-color; border-width: medium 1pt 1pt medium; padding: 0in 5.4pt; width: 243pt;" valign="top" width="324">
  <p style="margin: 0in 0in 0.0001pt;"><tt>T</tt>
  is <i>default constructed.</i></p>
  </td>
 </tr>
</tbody></table>

</div>






<hr>
<h3><a name="725"></a>725. Optional sequence container requirements column label</h3>
<p><b>Section:</b> 23.1.1 [sequence.reqmts] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> David Abrahams <b>Date:</b> 2007-09-16</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#sequence.reqmts">issues</a> in [sequence.reqmts].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Table 90: (Optional sequence container operations) states the
"assertion note pre/post-condition" of <tt>operator[]</tt> to be
</p>

<blockquote><pre>*(a.begin() + n)
</pre></blockquote>

<p>
Surely that's meant to be "operational semantics?"
</p>



<p><b>Proposed resolution:</b></p>
<blockquote>
<table border="1">
<caption>Table 90: Optional sequence container operations</caption>
<tbody><tr>
<th>expression</th> <th>return type</th> <th><del>assertion/note<br>pre/post-condition</del><br> <ins>operational semantics</ins></th> <th>container</th>
</tr>
</tbody></table>
</blockquote>






<hr>
<h3><a name="726"></a>726. Missing <tt>regex_replace()</tt> overloads</h3>
<p><b>Section:</b> 28.11.4 [re.alg.replace] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan T. Lavavej <b>Date:</b> 2007-09-22</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#re.alg.replace">active issues</a> in [re.alg.replace].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#re.alg.replace">issues</a> in [re.alg.replace].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Two overloads of <tt>regex_replace()</tt> are currently provided:
</p>

<blockquote><pre>template &lt;class OutputIterator, class BidirectionalIterator, 
    class traits, class charT&gt; 
  OutputIterator 
  regex_replace(OutputIterator out, 
                BidirectionalIterator first, BidirectionalIterator last, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const basic_string&lt;charT&gt;&amp; fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);
&nbsp;
template &lt;class traits, class charT&gt; 
  basic_string&lt;charT&gt; 
  regex_replace(const basic_string&lt;charT&gt;&amp; s, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const basic_string&lt;charT&gt;&amp; fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);
</pre></blockquote>

<ol>
<li>Overloads taking <tt>const charT *</tt> are provided for <tt>regex_match()</tt> and
<tt>regex_search()</tt>, but not <tt>regex_replace()</tt>.&nbsp; This is inconsistent.</li>
<li>
<p>The absence of <tt>const charT *</tt> overloads prevents ordinary-looking code from compiling, such as:</p>

<blockquote><pre>const string s("kitten");
const regex r("en");
cout &lt;&lt; regex_replace(s, r, "y") &lt;&lt; endl;
</pre></blockquote>

<p>
The compiler error message will be something like "could not deduce
template argument for 'const std::basic_string&lt;_Elem&gt; &amp;' from 'const
char[1]'".
</p>

<p>
Users expect that anything taking a <tt>basic_string&lt;charT&gt;</tt> can also take a
<tt>const charT *</tt>.&nbsp; In their own code, when they write a function taking
<tt>std::string</tt> (or <tt>std::wstring</tt>), they can pass a <tt>const char *</tt> (or <tt>const
wchar_t *</tt>), thanks to <tt>basic_string</tt>'s implicit constructor.&nbsp; Because the
regex algorithms are templated on <tt>charT</tt>, they can't rely on
<tt>basic_string</tt>'s implicit constructor (as the compiler error message
indicates, template argument deduction fails first).
</p>

<p>
If a user figures out what the compiler error message means, workarounds
are available - but they are all verbose.&nbsp; Explicit template arguments
could be given to <tt>regex_replace()</tt>, allowing <tt>basic_string</tt>'s implicit
constructor to be invoked - but <tt>charT</tt> is the last template argument, not
the first, so this would be extremely verbose.&nbsp; Therefore, constructing
a <tt>basic_string</tt> from each C string is the simplest workaround.
</p>
</li>

<li>
There is an efficiency consideration: constructing <tt>basic_string</tt>s can
impose performance costs that could be avoided by a library
implementation taking C strings and dealing with them directly.&nbsp;
(Currently, for replacement sources, C strings can be converted into
iterator pairs at the cost of verbosity, but for format strings, there
is no way to avoid constructing a <tt>basic_string</tt>.)
</li>
</ol>



<p><b>Proposed resolution:</b></p>
<p>
Provide additional overloads for <tt>regex_replace()</tt>: one additional
overload of the iterator-based form (taking <tt>const charT* fmt</tt>), and three
additional overloads of the convenience form (one taking <tt>const charT*
str</tt>, another taking <tt>const charT* fmt</tt>, and the third taking both <tt>const
charT* str</tt> and <tt>const charT* fmt</tt>).  28.11.4 [re.alg.replace]:
</p>

<blockquote>
<pre>template &lt;class OutputIterator, class BidirectionalIterator, 
    class traits, class charT&gt; 
  OutputIterator 
  regex_replace(OutputIterator out, 
                BidirectionalIterator first, BidirectionalIterator last, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const basic_string&lt;charT&gt;&amp; fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);

<ins>template &lt;class OutputIterator, class BidirectionalIterator, 
    class traits, class charT&gt; 
  OutputIterator 
  regex_replace(OutputIterator out, 
                BidirectionalIterator first, BidirectionalIterator last, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const charT* fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);</ins>
</pre>
<p>...</p>
<pre>template &lt;class traits, class charT&gt; 
  basic_string&lt;charT&gt; 
  regex_replace(const basic_string&lt;charT&gt;&amp; s, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const basic_string&lt;charT&gt;&amp; fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);

<ins>template &lt;class traits, class charT&gt; 
  basic_string&lt;charT&gt; 
  regex_replace(const basic_string&lt;charT&gt;&amp; s, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const charT* fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);</ins>

<ins>template &lt;class traits, class charT&gt; 
  basic_string&lt;charT&gt; 
  regex_replace(const charT* s, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const basic_string&lt;charT&gt;&amp; fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);</ins>

<ins>template &lt;class traits, class charT&gt; 
  basic_string&lt;charT&gt; 
  regex_replace(const charT* s, 
                const basic_regex&lt;charT, traits&gt;&amp; e, 
                const charT* fmt, 
                regex_constants::match_flag_type flags = 
                  regex_constants::match_default);</ins>
</pre>
</blockquote>






<hr>
<h3><a name="727"></a>727. <tt>regex_replace()</tt> doesn't accept <tt>basic_string</tt>s with custom traits and allocators</h3>
<p><b>Section:</b> 28.11.4 [re.alg.replace] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan T. Lavavej <b>Date:</b> 2007-09-22</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#re.alg.replace">active issues</a> in [re.alg.replace].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#re.alg.replace">issues</a> in [re.alg.replace].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<tt>regex_match()</tt> and <tt>regex_search()</tt> take <tt>const basic_string&lt;charT, ST,
SA&gt;&amp;</tt>.&nbsp; <tt>regex_replace()</tt> takes <tt>const basic_string&lt;charT&gt;&amp;</tt>.&nbsp; This prevents
<tt>regex_replace()</tt> from accepting <tt>basic_string</tt>s with custom traits and
allocators.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Overloads of <tt>regex_replace()</tt> taking <tt>basic_string</tt> should be additionally
templated on <tt>class ST, class SA</tt> and take <tt>const basic_string&lt;charT, ST,
SA&gt;&amp;</tt>.&nbsp; Consistency with <tt>regex_match()</tt> and <tt>regex_search()</tt> would place
<tt>class ST, class SA</tt> as the first template arguments; compatibility with
existing code using TR1 and giving explicit template arguments to
<tt>regex_replace()</tt> would place <tt>class ST, class SA</tt> as the last template
arguments.
</p>





<hr>
<h3><a name="728"></a>728. Problem in [rand.eng.mers]/6</h3>
<p><b>Section:</b> 26.4.3.2 [rand.eng.mers] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The <tt>mersenne_twister_engine</tt> is required to use a seeding method that is given 
as an algorithm parameterized over the number of bits <tt>W</tt>. I doubt whether the given generalization 
of an algorithm that was originally developed only for unsigned 32-bit integers is appropriate 
for other bit widths. For instance, <tt>W</tt> could be theoretically 16 and <tt>UIntType</tt> a 16-bit integer, in 
which case the given multiplier would not fit into the <tt>UIntType</tt>. Moreover, T. Nishimura and M. 
Matsumoto have chosen a dif ferent multiplier for their 64 bit Mersenne Twister
[<a href="http://www.math.sci.hiroshima-u.ac.jp/%7Em-mat/MT/VERSIONS/C-LANG/mt19937-64.c">reference</a>].
</p>

<p>
I see two possible resolutions: 
</p>

<ol type="a">
<li>Restrict the parameter <tt>W</tt> of the <tt>mersenne_twister_template</tt> to values of 32 or 64 and use the 
multiplier from [the above reference] for the 64-bit case (my preference)</li>
<li>Interpret the state array for any <tt>W</tt> as a 32-bit array of appropriate length (and a specified byte 
order) and always employ the 32-bit algorithm for seeding
</li>
</ol>

<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for further discussion.
</p>



<p><b>Proposed resolution:</b></p>

<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>






<hr>
<h3><a name="729"></a>729. Problem in [rand.req.eng]/3</h3>
<p><b>Section:</b> 26.4.1.3 [rand.req.eng] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#rand.req.eng">issues</a> in [rand.req.eng].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The 3rd table row in 26.4.1.3 [rand.req.eng]/3 requires random number engines to accept any 
arithmetic type as a seed, which is then casted to the engine's <tt>result_type</tt> and subsequently 
used for seeding the state of the engine. The requirement stated as "Creates an engine with 
initial state determined by <tt>static_cast&lt;X::result_type&gt;(s)</tt>" forces random number engines 
to either use a seeding method that completely depends on the <tt>result_type</tt> (see the discussion 
of seeding for the <tt>mersenne_twister_engine</tt> in point T2 above) or at least to throw away "bits 
of randomness" in the seed value if the <tt>result_type</tt> is smaller than the seed type. This seems 
to be inappropriate for many modern random number generators, in particular F2-linear or 
cryptographic ones, which operate on an internal bit array that in principle is independent of the 
type of numbers returned.
</p>

<p>
<b>Posible resolution:</b> I propose to change the wording to a version similar to "Creates an 
engine with initial state determined by <tt>static_cast&lt;UintType&gt;(s)</tt>, where <tt>UintType</tt> is an 
implementation specific unsigned integer type."
</p>

<p>
Additionally, the definition of s in 26.4.1.3 [rand.req.eng]/1 c) could be restricted to unsigned integer types.
</p>

<p>
Similarly, the type of the seed in 26.4.1.4 [rand.req.adapt]/3 e) could be left unspecified.
</p>

<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for further discussion.
</p>



<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for further discussion.
</p>






<hr>
<h3><a name="730"></a>730. Comment on [rand.req.adapt]/3 e)</h3>
<p><b>Section:</b> 26.4.1.4 [rand.req.adapt] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
If an engine adaptor is invoked with an argument of type <tt>seed_seq</tt>, then all base 
engines are specified to be seeded with this <tt>seed_seq</tt>. As <tt>seed_seq</tt>'s randomization method is 
qualified as constant, this procedure will ef fectively initialize all base engines with the same seed 
(though the resulting state might still dif fer to a certain degree if the engines are of different types). 
It is not clear whether this mode of operation is in general appropriate, hence -- as far as the 
stated requirements are of general nature and not just specific to the engine adaptors provided by 
the library -- it might be better to leave the behaviour unspecified, since the current definition of 
<tt>seed_seq</tt> does not allow for a generally satisfying specification.
</p>

<p>
<b>Posssible resolution:</b> [As above]
</p>

<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for further discussion.
</p>



<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="731"></a>731. proposal for a customizable <tt>seed_seq</tt></h3>
<p><b>Section:</b> 26.4.7.1 [rand.util.seedseq] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#rand.util.seedseq">issues</a> in [rand.util.seedseq].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The proper way to seed random number engines seems to be the most frequently 
discussed issue of the 26.4 [rand] proposal. While the new <tt>seed_seq</tt> approach is already rather 
general and probably sufficient for most situations, it is unlikely to be optimal in every case (one 
problem was pointed out in point T5 above). In some situations it might, for instance, be better to 
seed the state with a cryptographic generator. 
</p>
<p>
In my opinion this is a pretty strong argument for extending the standard with a simple facility to 
customize the seeding procedure. This could, for example, be done with the following minimal 
changes:
</p>

<p>
<b>Possible resolution:</b>
</p>

<ol type="a">
<li>
Turn the interface specification of 26.4.7.1 [rand.util.seedseq]/2 into a "SeedSeq" requirement, where the 
exact behaviour of the constructors and the randomize method are left unspecified and where the
const qualification for randomize is removed. Classes implementing this interface are additionally 
required to specialize the traits class in c).
</li>
<li>
Provide the class <tt>seed_seq</tt> as a default implementation of the SeedSeq interface.
</li>
<li>
<p>
Supplement the <tt>seed_seq</tt> with a traits class
</p>
<blockquote><pre>template &lt;typename T&gt; 
struct is_seed_seq { static const bool value = false; }
</pre></blockquote>
<p>and the specialization</p>
<blockquote><pre>template &lt;&gt; 
struct is_seed_seq&lt;seed_seq&gt; { static const bool value = true; }
</pre></blockquote>
<p>which users can supplement with further specializations.</p>
</li>
<li>
Change 26.4.1.3 [rand.req.eng]/1 d) to "q is an lvalue of a type that fulfils the SeedSeq requirements", and 
modify the constructors and seed methods in 26.4.3 [rand.eng] appropriately (the actual implementation 
could be done using the SFINAE technique).
</li>
</ol>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="732"></a>732. Defect in [rand.dist.samp.genpdf]</h3>
<p><b>Section:</b> 26.4.8.5.3 [rand.dist.samp.genpdf] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
26.4.8.5.3 [rand.dist.samp.genpdf] describes the interface for a distribution template that is 
meant to simulate random numbers from any general distribution given only the density and the 
support of the distribution. I'm not aware of any general purpose algorithm that would be capable 
of correctly and efficiently implementing the described functionality. From what I know, this is 
essentially an unsolved research problem. Existing algorithms either require more knowledge 
about the distribution and the problem domain or work only under very limited circumstances. 
Even the state of the art special purpose library UNU.RAN does not solve the problem in full 
generality, and in any case, testing and customer support for such a library feature would be a 
nightmare.
</p>

<p>
<b>Possible resolution:</b> For these reasons, I propose to delete section 26.4.8.5.3 [rand.dist.samp.genpdf].
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="733"></a>733. Comment on [rand.req.dist]/9</h3>
<p><b>Section:</b> 26.4.1.5 [rand.req.dist] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The requirement "P shall have a declaration of the form <tt>typedef X distribution_- 
type</tt>" effectively makes the use of inheritance for implementing distributions very inconvenient, 
because the child of a distribution class in general will not satisfy this requirement. In my opinion 
the benefits of having a typedef in the parameter class pointing back to the distribution class are 
not worth the hassle this requirement causes. [In my code base I never made use of the nested 
typedef but on several occasions could have profited from being able to use simple inheritance for 
the implementation of a distribution class.]
</p>

<p>
<b>Proposed resolution:</b> I propose to drop this requirement.
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="734"></a>734. Unnecessary restriction in [rand.dist.norm.chisq]</h3>
<p><b>Section:</b> 26.4.8.4.3 [rand.dist.norm.chisq] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
<tt>chi_squared_distribution</tt>, <tt>fisher_f_distribution</tt> and <tt>student_t_distribution</tt>
have parameters for the "degrees of freedom" <tt>n</tt> and <tt>m</tt> that are specified as integers. For the 
following two reasons this is an unnecessary restriction: First, in many applications such as 
Bayesian inference or Monte Carlo simulations it is more convenient to treat the respective param- 
eters as continuous variables. Second, the standard non-naive algorithms (i.e. 
O(1) algorithms) 
for simulating from these distributions work with floating-point parameters anyway (all three 
distributions could be easily implemented using the Gamma distribution, for instance).
</p>

<p>
Similar arguments could in principle be made for the parameters <tt>t</tt> and <tt>k</tt> of the discrete 
<tt>binomial_distribution</tt> and <tt>negative_binomial_distribution</tt>, though in both cases continuous
parameters are less frequently used in practice and in case of the <tt>binomial_distribution</tt>
the implementation would be significantly complicated by a non-discrete parameter (in most 
implementations one would need an approximation of the log-gamma function instead of just the 
log-factorial function).
</p>

<p>
<b>Possible resolution:</b> For these reasons, I propose to change the type of the respective parameters 
to double.
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="735"></a>735. Unfortunate naming</h3>
<p><b>Section:</b> 26.4.8.2.2 [rand.dist.bern.bin], 26.4.8.2.4 [rand.dist.bern.negbin] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In my opinion the choice of name for the <tt>t</tt> parameter of the <tt>binomial_distribution</tt>
is very unfortunate. In virtually every internet reference, book and software implementation 
this parameter is called <tt>n</tt> instead, see for example Wikipedia, Mathworld, Evans et al. (1993) 
Statistical Distributions, 2nd E., Wiley, p. 38, the R statistical computing language, p. 926, 
Mathematica and Matlab.
</p>

<p>
Similarly, the choice of <tt>k</tt> for the parameter of the negative binomial distributions is rather unusual. 
The most common choice for the negative binomial distribution seems to be <tt>r</tt> instead.
</p>

<p>
Choosing unusual names for the parameters causes confusion among users and makes the 
interface unnecessarily inconvenient to use.
</p>

<p>
<b>Possible resolution:</b> For these reasons, I propose to change the name of the respective parameters
to <tt>n</tt> and <tt>r</tt>.
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="736"></a>736. Comment on [rand.dist.samp.discrete]</h3>
<p><b>Section:</b> 26.4.8.5.1 [rand.dist.samp.discrete] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<ol type="a">
<li>
The specification for <tt>discrete_distribution</tt> requires the member <tt>probabilities()</tt>
to return a vector of <i>standardized</i> probabilities, which forces the implementation every time to 
divide each probability by the sum of all probabilities, as the sum will in practice almost never be 
exactly 1.0. This is unnecessarily inef ficient as the implementation would otherwise not need to 
compute the standardized probabilities at all and could instead work with the non-standardized 
probabilities and the sum. If there was no standardization the user would just get back the 
probabilities that were previously supplied to the distribution object, which to me seems to be the 
more obvious solution.
</li>
<li>
The behaviour of <tt>discrete_distribution</tt> is not specified in case the number of given
probabilities is larger than the maximum number representable by the IntType.
</li>
</ol>

<p>
<b>Possible resolution:</b> I propose to change the specification such that the non-standardized 
probabilities need to be returned and that an additional requirement is included for the number 
of probabilities to be smaller than the maximum of IntType.
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="737"></a>737. Comment on [rand.dist.samp.pconst]</h3>
<p><b>Section:</b> 26.4.8.5.2 [rand.dist.samp.pconst] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<ol type="a">
<li>
The discussion in point T11 above regarding <tt>probabilities()</tt> similarly applies 
to the method <tt>densities()</tt> of <tt>piecewise_constant_distribution</tt>.
</li>
<li>
<p>
The design of the constructor
</p>
<blockquote><pre>template &lt;class InputIteratorB, class InputIteratorW&gt; 
piecewise_constant_distribution( InputIteratorB firstB, InputIteratorB lastB, 
                                 InputIteratorW firstW);
</pre></blockquote>
<p>
is unnecessarily unsafe, as there is no separate end-iterator given for the weights. I can't see 
any performance or convenience reasons that would justify the risks inherent in such a function 
interface, in particular the risk that input error might go unnoticed.
</p>
</li>
</ol>

<p>
<b>Possible resolution:</b> I propose to add an <tt>InputIteratorW lastW</tt> argument to the interface.
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="738"></a>738. Editorial issue in [rand.adapt.disc]/3</h3>
<p><b>Section:</b> 26.4.4.1 [rand.adapt.disc] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Since the template parameter <tt>p</tt> and <tt>r</tt> are of type <tt>size_t</tt>, the member <tt>n</tt> in the class 
exposition should have type <tt>size_t</tt>, too.
</p>


<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="739"></a>739. Defect in [rand.util.canonical]/3</h3>
<p><b>Section:</b> 26.4.7.2 [rand.util.canonical] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Stephan Tolksdorf <b>Date:</b> 2007-09-21</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#rand.util.canonical">issues</a> in [rand.util.canonical].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The complexity of <tt>generate_canonical</tt> is specified to be "exactly k=max(1, ceil(b/log2 
R)) invocations of g". This terms involves a logarithm that is not rounded and hence can not (in 
general) be computed at compile time. As this function template is performance critical, I propose 
to replace ceil(b/log2 R) with ceil(b/floor(log2 R)).
</p>

<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for further discussion.
</p>



<p><b>Proposed resolution:</b></p>
<p>
See <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2423.pdf">N2423</a>
for the proposed resolution.
</p>





<hr>
<h3><a name="740"></a>740. Please remove <tt>*_ptr&lt;T[N]&gt;</tt></h3>
<p><b>Section:</b> 20.6.5.4 [unique.ptr.compiletime] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Herb Sutter <b>Date:</b> 2007-10-04</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Please don't provide <tt>*_ptr&lt;T[N]&gt;</tt>. It doesn't enable any useful
bounds-checking (e.g., you could imagine that doing <tt>op++</tt> on a
<tt>shared_ptr&lt;T[N]&gt;</tt> yields a <tt>shared_ptr&lt;T[N-1]&gt;</tt>, but that promising path
immediately falters on <tt>op--</tt> which can't reliably dereference because we
don't know the lower bound). Also, most buffers you'd want to point to
don't have a compile-time known size.
</p>

<p>
To enable any bounds-checking would require run-time information, with
the usual triplet: base (lower bound), current offset, and max offset
(upper  bound). And I can sympathize with the point of view that you
wouldn't want to require this on <tt>*_ptr</tt> itself. But please let's not
follow the <tt>&lt;T[N]&gt;</tt> path, especially not with additional functions to
query the bounds etc., because this sets wrong user expectations by
embarking on a path that doesn't go all the way to bounds checking as it
seems to imply.
</p>

<p>
If bounds checking is desired, consider a <tt>checked_*_ptr</tt> instead (e.g.,
<tt>checked_shared_ptr</tt>). And make the interfaces otherwise identical so that
user code could easily <tt>#define/typedef</tt> between prepending <tt>checked_</tt> on
debug builds and not doing so on release builds (for example).
</p>

<p>
Note that some may object that <tt>checked_*_ptr</tt> may seem to make the smart
pointer more like <tt>vector</tt>, and we don't want two ways to spell <tt>vector</tt>. I
don't agree, but if that were true that would be another reason to
remove <tt>*_ptr&lt;T[N]&gt;</tt> which equally makes the smart pointer more like
<tt>std::array.</tt> :-)
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change the synopsis under 20.6.5 [unique.ptr] p2:
</p>

<blockquote><pre>...
template&lt;class T&gt; struct default_delete; 
template&lt;class T&gt; struct default_delete&lt;T[]&gt;; 
<del>template&lt;class T, size_t N&gt; struct default_delete&lt;T[N]&gt;;</del>

template&lt;class T, class D = default_delete&lt;T&gt;&gt; class unique_ptr; 
template&lt;class T, class D&gt; class unique_ptr&lt;T[], D&gt;; 
<del>template&lt;class T, class D, size_t N&gt; class unique_ptr&lt;T[N], D&gt;;</del>
...
</pre></blockquote>

<p>
Remove the entire section 20.6.5.1.3 [unique.ptr.dltr.dflt2] <b><tt>default_delete&lt;T[N]&gt;</tt></b>.
</p>

<p>
Remove the entire section 20.6.5.4 [unique.ptr.compiletime] <b><tt>unique_ptr</tt> for array objects with a compile time length</b>
and its subsections: 20.6.5.4.1 [unique.ptr.compiletime.dtor], 20.6.5.4.2 [unique.ptr.compiletime.observers],
20.6.5.4.3 [unique.ptr.compiletime.modifiers].
</p>






<hr>
<h3><a name="741"></a>741. Const-incorrect <tt>get_deleter</tt> function for <tt>shared_ptr</tt></h3>
<p><b>Section:</b> 20.6.6.2.11 [util.smartptr.getdeleter] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-09-27</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#util.smartptr.getdeleter">issues</a> in [util.smartptr.getdeleter].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The following issue was raised by Alf P. Steinbach in c.l.c++.mod:
</p>

<p>
According to the recent draft N2369, both the header memory synopsis
of 20.6 [memory] and 20.6.6.2.11 [util.smartptr.getdeleter] declare:
</p>

<blockquote><pre>template&lt;class D, class T&gt; D* get_deleter(shared_ptr&lt;T&gt; const&amp; p);
</pre></blockquote>

<p>
This allows to retrieve the pointer to a mutable deleter of a <tt>const
shared_ptr</tt> (if that owns one) and therefore contradicts the usual
philosophy that associated functors are either read-only (e.g.
<tt>key_comp</tt> or <tt>value_comp</tt> of <tt>std::map</tt>) or do at least reflect
the mutability of the owner (as seen for the both overloads of
<tt>unique_ptr::get_deleter</tt>).
Even the next similar counter-part of <tt>get_deleter</tt> - the two
overloads of <tt>function::target</tt> in the class template function
synopsis 20.5.15.2 [func.wrap.func] or in 20.5.15.2.5 [func.wrap.func.targ] - do
properly mirror the const-state of the owner.
</p>

<b>Possible proposed resolutions:</b>

<p>
Replace the declarations of <tt>get_deleter</tt> in the header <tt>&lt;memory&gt;</tt>
synopsis of 20.6 [memory] and in 20.6.6.2.11 [util.smartptr.getdeleter] by one of the
following alternatives (A) or (B):
</p>

<ol type="A">
<li>
Provide <b>only</b> the immutable variant. This would reflect the
current praxis of <tt>container::get_allocator()</tt>, <tt>map::key_comp()</tt>, or
<tt>map::value_comp</tt>.

<blockquote><pre>template&lt;class D, class T&gt; const D* get_deleter(shared_ptr&lt;T&gt; const&amp; p);
</pre></blockquote>
</li>
<li>
Just remove the function.
</li>
</ol>

<p>
Alberto Ganesh Barbati adds:
</p>

<ol start="3" type="A">
<li>
<p>
Replace it with two functions:
</p>
<blockquote><pre>template &lt;class D, class T&gt; D get_deleter(shared_ptr&lt;T&gt; const&amp;);
template &lt;class D, class T&gt; bool has_deleter(shared_ptr&lt;T&gt; const&amp;);
</pre></blockquote>

<p>
The first one would throw if <tt>D</tt> is the wrong type, while the latter would
never throw. This approach would reflect the current praxis of
<tt>use_facet/has_facet</tt>, with the twist of returning the deleter by value as
<tt>container::get_allocator()</tt> do.
</p>
</li>
</ol>

<p>
Peter Dimov adds:
</p>

<blockquote>
<p>
My favorite option is "not a defect". A, B and C break useful code.
</p>
</blockquote>



<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="742"></a>742. Enabling <tt>swap</tt> for proxy iterators</h3>
<p><b>Section:</b> 20.1.1 [utility.arg.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#utility.arg.requirements">active issues</a> in [utility.arg.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#utility.arg.requirements">issues</a> in [utility.arg.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
This issue was split from <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#672">672</a>. <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#672">672</a> now just
deals with changing the requirements of <tt>T</tt> in the <tt>Swappable</tt>
requirement from <tt>CopyConstructible</tt> and <tt>CopyAssignable</tt> to
<tt>MoveConstructible</tt> and <tt>MoveAssignable</tt>.
</p>

<p>
This issue seeks to widen the <tt>Swappable</tt> requirement to support proxy iterators.  Here
is example code:
</p>

<blockquote><pre>namespace Mine {

template &lt;class T&gt;
struct proxy {...};

template &lt;class T&gt;
struct proxied_iterator
{
   typedef T value_type;
   typedef proxy&lt;T&gt; reference;
   reference operator*() const;
   ...
};

struct A
{
   // heavy type, has an optimized swap, maybe isn't even copyable or movable, just swappable
   void swap(A&amp;);
   ...
};

void swap(A&amp;, A&amp;);
void swap(proxy&lt;A&gt;, A&amp;);
void swap(A&amp;, proxy&lt;A&gt;);
void swap(proxy&lt;A&gt;, proxy&lt;A&gt;);

}  // Mine

...

Mine::proxied_iterator&lt;Mine::A&gt; i(...)
Mine::A a;
<b>swap(*i1, a);</b>
</pre></blockquote>

<p>
The key point to note in the above code is that in the call to <tt>swap</tt>, <tt>*i1</tt>
and <tt>a</tt> are different types (currently types can only be <tt>Swappable</tt> with the
same type).  A secondary point is that to support proxies, one must be able to pass rvalues
to <tt>swap</tt>.  But note that I am not stating that the general purpose <tt>std::swap</tt>
should accept rvalues!  Only that overloaded <tt>swap</tt>s, as in the example above, be allowed
to take rvalues.
</p>

<p>
That is, no standard library code needs to change.  We simply need to have a more flexible
definition of <tt>Swappable</tt>.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change 20.1.1 [utility.arg.requirements]:
</p>

<blockquote>

<p>
-1- The template definitions in the C++ Standard Library refer to various
named requirements whose details are set out in tables 31-38. In these
tables, <tt>T</tt> <ins>and <tt>V</tt> are</ins> <del>is a</del> type<ins>s</ins> to be supplied by a C++ program
instantiating a template; <tt>a</tt>, <tt>b</tt>, and <tt>c</tt> are
values of type <tt>const T</tt>; <tt>s</tt> and <tt>t</tt> are modifiable
lvalues of type <tt>T</tt>; <tt>u</tt> is a value of type (possibly
<tt>const</tt>) <tt>T</tt>; <del>and</del> <tt>rv</tt> is a non-<tt>const</tt>
rvalue of type <tt>T</tt><ins>; <tt>w</tt> is a value of type <tt>T</tt>; and <tt>v</tt> is a value of type <tt>V</tt></ins>.
</p>

<table border="1">
<caption>Table 37: <tt>Swappable</tt> requirements <b>[swappable]</b></caption>
<tbody><tr><th>expression</th><th>return type</th><th>post-condition</th></tr>
<tr><td><tt>swap(<del>s</del><ins>w</ins>,<del>t</del><ins>v</ins>)</tt></td><td><tt>void</tt></td>
<td><del><tt>t</tt></del><ins><tt>w</tt></ins> has the value originally
held by <del><tt>u</tt></del><ins><tt>v</tt></ins>, and
<del><tt>u</tt></del><ins><tt>v</tt></ins> has the value originally held
by <del><tt>t</tt></del><ins><tt>w</tt></ins></td></tr>
<tr><td colspan="3">
<p>
The <tt>Swappable</tt> requirement is met by satisfying one or more of the following conditions:
</p>
<ul>
<li>
<tt>T</tt> is <tt>Swappable</tt> if <ins><tt>T</tt> and <tt>V</tt> are
the same type and </ins> <tt>T</tt> satisfies the
<del><tt>CopyConstructible</tt></del>
<ins><tt>MoveConstructible</tt></ins> requirements (Table <del>34</del>
<ins>33</ins>) and the <del><tt>CopyAssignable</tt></del>
<ins><tt>MoveAssignable</tt></ins> requirements (Table <del>36</del>
<ins>35</ins>);
</li>
<li>
<tt>T</tt> is <tt>Swappable</tt> <ins>with <tt>V</tt></ins> if a namespace scope function named
<tt>swap</tt> exists in the same namespace as the definition of
<tt>T</tt> <ins>or <tt>V</tt></ins>, such that the expression
<tt>swap(<del>t</del><ins>w</ins>,<del>u</del> <ins>v</ins>)</tt> is valid and has the
semantics described in this table.
</li>
</ul>
</td></tr>
</tbody></table>
</blockquote>






<hr>
<h3><a name="743"></a>743. rvalue <tt>swap</tt> for <tt>shared_ptr</tt></h3>
<p><b>Section:</b> 20.6.6.2.9 [util.smartptr.shared.spec] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Howard Hinnant <b>Date:</b> 2007-10-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
When the LWG looked at <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#674">674</a> in Kona the following note was made:
</p>

<blockquote><p>
We may need to open an issue to deal with the question of
whether <tt>shared_ptr</tt> needs an rvalue <tt>swap</tt>.
</p></blockquote>

<p>
This issue was opened in response to that note.
</p>

<p>
I believe allowing rvalue <tt>shared_ptr</tt>s to <tt>swap</tt> is both
appropriate, and consistent with how other library components are currently specified.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change the synopsis in 20.6.6.2 [util.smartptr.shared]:
</p>

<blockquote><pre>void swap(shared_ptr&amp;<ins>&amp;</ins> r);
...
template&lt;class T&gt; void swap(shared_ptr&lt;T&gt;&amp; a, shared_ptr&lt;T&gt;&amp; b);
<ins>template&lt;class T&gt; void swap(shared_ptr&lt;T&gt;&amp;&amp; a, shared_ptr&lt;T&gt;&amp; b);
template&lt;class T&gt; void swap(shared_ptr&lt;T&gt;&amp; a, shared_ptr&lt;T&gt;&amp;&amp; b);</ins>
</pre></blockquote>

<p>
Change 20.6.6.2.4 [util.smartptr.shared.mod]:
</p>

<blockquote><pre>void swap(shared_ptr&amp;<ins>&amp;</ins> r);
</pre></blockquote>

<p>
Change 20.6.6.2.9 [util.smartptr.shared.spec]:
</p>

<blockquote><pre>template&lt;class T&gt; void swap(shared_ptr&lt;T&gt;&amp; a, shared_ptr&lt;T&gt;&amp; b);
<ins>template&lt;class T&gt; void swap(shared_ptr&lt;T&gt;&amp;&amp; a, shared_ptr&lt;T&gt;&amp; b);
template&lt;class T&gt; void swap(shared_ptr&lt;T&gt;&amp; a, shared_ptr&lt;T&gt;&amp;&amp; b);</ins>
</pre></blockquote>





<hr>
<h3><a name="744"></a>744. What is the lifetime of an exception pointed to by an exception_ptr?</h3>
<p><b>Section:</b> 18.7.5 [propagation] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#propagation">active issues</a> in [propagation].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#propagation">issues</a> in [propagation].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Without some lifetime guarantee, it is hard to know how this type can be
used. &nbsp;Very specifically, I don't see how the current wording would
guarantee and exception_ptr caught at the end of one thread could be safely
stored and rethrown in another thread - the original motivation for this
API.
</p>
<p>
(Peter Dimov agreed it should be clearer, maybe a non-normative note to
explain?)
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="745"></a>745. copy_exception API slices.</h3>
<p><b>Section:</b> 18.7.5 [propagation] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#propagation">active issues</a> in [propagation].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#propagation">issues</a> in [propagation].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
It could be I did not understand the design rationale, but I thought
copy_exception would produce an exception_ptr to the most-derived (dynamic)
type of the passed exception. &nbsp;Instead it slices, which appears to be less
useful, and a likely source of FAQ questions in the future.
</p>
<p>
(Peter Dimov suggests NAD)
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="746"></a>746. current_exception may fail with bad_alloc</h3>
<p><b>Section:</b> 18.7.5 [propagation] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#propagation">active issues</a> in [propagation].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#propagation">issues</a> in [propagation].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I understand that the attempt to copy an exception may run out of memory,
but I believe this is the only part of the standard that mandates failure
with specifically <tt>bad_alloc</tt>, as opposed to allowing an
implementation-defined type derived from <tt>bad_alloc</tt>. &nbsp;For instance, the Core
language for a failed new expression is:
</p>
<blockquote>
<p>
Any other allocation function that fails to allocate storage shall indicate
failure only by throwing an exception of a type that would match a handler
(15.3) of type <tt>std::bad_alloc</tt> (18.5.2.1).
</p>
</blockquote>
<p>
I think we should allow similar freedom here (or add a blanket
compatible-exception freedom paragraph in 17)
</p>
<p>
I prefer the clause 17 approach myself, and maybe clean up any outstanding
wording that could also rely on it.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="747"></a>747. We have 3 separate type traits to identify classes supporting no-throw operations</h3>
<p><b>Section:</b> 20.4.4.3 [meta.unary.prop] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#meta.unary.prop">active issues</a> in [meta.unary.prop].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#meta.unary.prop">issues</a> in [meta.unary.prop].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
We have 3 separate type traits to identify classes supporting no-throw
operations, which are very useful when trying to provide exception safety
guarantees. &nbsp;However, I'm not entirely clear on what the current wording
requires of a conforming implementation. &nbsp;To quote from
<tt>has_nothrow_default_constructor</tt>:
</p>
<blockquote><p>
or <tt>T</tt> is a class type with a default constructor that is known not to throw
any exceptions
</p></blockquote>
<p>
What level of magic do we expect to deduce if this is known?
</p>
<p>
E.g.
</p>

<blockquote><pre>struct test{
&nbsp;int x;
&nbsp;test() : x() {}
};
</pre></blockquote>
<p>
Should I expect a conforming compiler to 
&nbsp;<tt>assert( has_nothrow_constructor&lt;test&gt;::value )</tt>
</p>
<p>
Is this a QoI issue?
</p>
<p>
Should I expect to 'know' only if-and-only-if there is an inline definition
available?
</p>
<p>
Should I never expect that to be true, and insist that the user supplies an
empty throw spec if they want to assert the no-throw guarantee?
</p>
<p>
It would be helpful to maybe have a footnote explaining what is required,
but right now I don't know what to suggest putting in the footnote.
</p>
<p>
(agreement since is that trivial ops and explicit no-throws are required.
Open if QoI should be allowed to detect further)
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="748"></a>748. The is_abstract type trait is defined by reference to 10.4.</h3>
<p><b>Section:</b> 20.4.4.3 [meta.unary.prop] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#meta.unary.prop">active issues</a> in [meta.unary.prop].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#meta.unary.prop">issues</a> in [meta.unary.prop].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
I am trying to decide is a pure virtual function is a <i>necessary</i> as well as
sufficient requirement to be classified as abstract?
</p>
<p>
For instance, is the following (non-polymorphic) type considered abstract?
</p>
<blockquote><pre>struct abstract {
protected:
&nbsp;abstract(){}
&nbsp;abstract( abstract const &amp; ) {}
&nbsp;~abstract() {}
};
</pre></blockquote>
<p>
(Suggested that this may be NAD, with an editorial fix-up from Pete on the
core wording to make clear that abstract requires a pure virtual function)
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="749"></a>749. Currently <tt>has_nothrow_copy_constructor&lt;T&gt;::value</tt> is true if T has 'a' nothrow copy constructor.</h3>
<p><b>Section:</b> 20.4.4.3 [meta.unary.prop] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#meta.unary.prop">active issues</a> in [meta.unary.prop].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#meta.unary.prop">issues</a> in [meta.unary.prop].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Unfortunately a class can have multiple copy constructors, and I believe to
be useful this trait should only return true is ALL copy constructors are
no-throw.
</p>
<p>
For instance:
</p>
<blockquote>
<pre>struct awkward {
&nbsp;awkward( const awkward &amp; ) throw() {}
&nbsp;awkward( awkward &amp; ) { throw "oops"; } };
</pre>
</blockquote>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="750"></a>750. The current definition for <tt>is_convertible</tt> requires that the type be
implicitly convertible, so explicit constructors are ignored.</h3>
<p><b>Section:</b> 20.4.5 [meta.rel] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
With the pending arrival of explicit conversion functions though, I'm
wondering if we want an additional trait, <tt>is_explictly_convertible</tt>?
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="751"></a>751. change pass-by-reference members of <tt>vector&lt;bool&gt;</tt> to pass-by-value?</h3>
<p><b>Section:</b> 23.2.6 [vector.bool] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Alisdair Meredith <b>Date:</b> 2007-10-10</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
A number of vector&lt;bool&gt; members take const bool&amp; as arguments.
Is there any chance we could change them to pass-by-value or would I 
be wasting everyone's time if wrote up an issue?
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="752"></a>752. Allocator complexity requirement</h3>
<p><b>Section:</b> 20.1.2 [allocator.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Hans Boehm <b>Date:</b> 2007-10-11</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#allocator.requirements">active issues</a> in [allocator.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#allocator.requirements">issues</a> in [allocator.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Did LWG recently discuss 20.1.2 [allocator.requirements]-2, which states that "All the operations
on the allocators are expected to be amortized constant time."?
</p>
<p>
As I think I pointed out earlier, this is currently fiction for
<tt>allocate()</tt> if it has to obtain memory from the OS, and it's unclear to
me how to interpret this for <tt>construct()</tt> and <tt>destroy()</tt> if they deal with
large objects. &nbsp;Would it be controversial to officially let these take
time linear in the size of the object, as they already do in real life?
</p>
<p>
<tt>Allocate()</tt> more blatantly takes time proportional to the size of the
object if you mix in GC. &nbsp;But it's not really a new problem, and I think
we'd be confusing things by leaving the bogus requirements there. &nbsp;The
current requirement on <tt>allocate()</tt> is generally not important anyway,
since it takes O(size) to construct objects in the resulting space.
There are real performance issues here, but they're all concerned with
the constants, not the asymptotic complexity.
</p>


<p><b>Proposed resolution:</b></p>
<p>
Change 20.1.2 [allocator.requirements]/2:
</p>

<blockquote>
<p>
-2- Table 39 describes the requirements on types manipulated through
allocators. All the operations on the allocators are expected to be
amortized constant time<ins>, except that <tt>allocate</tt> and
<tt>construct</tt> may require time proportional to the size of the
object allocated or constructed</ins>. Table 40 describes the
requirements on allocator types.
</p>
</blockquote>





<hr>
<h3><a name="753"></a>753. Move constructor in draft</h3>
<p><b>Section:</b> 20.1.1 [utility.arg.requirements] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Yechezkel Mett <b>Date:</b> 2007-10-14</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#utility.arg.requirements">active issues</a> in [utility.arg.requirements].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#utility.arg.requirements">issues</a> in [utility.arg.requirements].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The draft standard n2369 uses the term <i>move constructor</i> in a few
places, but doesn't seem to define it.
</p>

<p>
<tt>MoveConstructible</tt> requirements are defined in Table 33 in 20.1.1 [utility.arg.requirements] as
follows:
</p>

<blockquote>
<table border="1">
<caption><tt>MoveConstructible</tt> requirements</caption>
<tbody><tr>
<th>expression</th> <th>post-condition</th>
</tr>
<tr>
<td><tt>T t = rv</tt></td> <td><tt>t</tt> is equivalent to the value of <tt>rv</tt> before the construction</td>
</tr>
<tr>
<td colspan="2">[<i>Note:</i> There is no requirement on the value of <tt>rv</tt> after the 
construction. <i>-- end note</i>]</td>
</tr>
</tbody></table>
</blockquote>

<p>
(where <tt>rv</tt> is a non-const rvalue of type <tt>T</tt>).
</p>

<p>
So I assume the move constructor is the constructor that would be used
in filling the above requirement.
</p>

<p>
For <tt>vector::reserve</tt>, <tt>vector::resize</tt> and the <tt>vector</tt> modifiers given in
23.2.5.4 [vector.modifiers] we have
</p>

<blockquote>
<i>Requires:</i> If <tt>value_type</tt> has a move constructor, that constructor shall
not throw any exceptions.
</blockquote>

<p>
Firstly "If <tt>value_type</tt> has a move constructor" is superfluous; every
type which can be put into a <tt>vector</tt> has a move constructor (a copy
constructor is also a move constructor). Secondly it means that for
any <tt>value_type</tt> which has a throwing copy constructor and no other move
constructor these functions cannot be used -- which I think will come
as a shock to people who have been using such types in <tt>vector</tt> until
now!
</p>

<p>
I can see two ways to correct this. The simpler, which is presumably
what was intended, is to say "If <tt>value_type</tt> has a move constructor and
no copy constructor, the move constructor shall not throw any
exceptions" or "If <tt>value_type</tt> has a move constructor which changes the
value of its parameter,".
</p>

<p>
The other alternative is add to <tt>MoveConstructible</tt> the requirement that
the expression does not throw. This would mean that not every type
that satisfies the <tt>CopyConstructible</tt> requirements also satisfies the
<tt>MoveConstructible</tt> requirements. It would mean changing requirements in
various places in the draft to allow either <tt>MoveConstructible</tt> or
<tt>CopyConstructible</tt>, but I think the result would be clearer and
possibly more concise too.
</p>


<p><b>Proposed resolution:</b></p>
<p>
</p>





<hr>
<h3><a name="754"></a>754. Ambiguous return clause for <tt>std::uninitialized_copy</tt></h3>
<p><b>Section:</b> 20.6.4.1 [uninitialized.copy] <b>Status:</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#New">New</a>
 <b>Submitter:</b> Daniel Krügler <b>Date:</b> 2007-10-15</p>
<p><b>View other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index-open.html#uninitialized.copy">active issues</a> in [uninitialized.copy].</p>
<p><b>View all other</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-index.html#uninitialized.copy">issues</a> in [uninitialized.copy].</p>
<p><b>View all issues with</b> <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
14882-2003, [lib.uninitialized.copy] is currently written as follows:
</p>

<blockquote>
<pre>template &lt;class InputIterator, class ForwardIterator&gt;
  ForwardIterator uninitialized_copy(InputIterator <i>first</i>, InputIterator <i>last</i>,
                                     ForwardIterator <i>result</i>);
</pre>
<blockquote>
<p>
-1- <i>Effects:</i>
</p>
<blockquote><pre>for (; first != last; ++result, ++first)
  new (static_cast&lt;void*&gt;(&amp;*result))
    typename iterator_traits&lt;ForwardIterator&gt;::value_type(*first);
</pre></blockquote>
<p>
-2- <i>Returns:</i> <tt><i>result</i></tt>
</p>
</blockquote>
</blockquote>

<p>
similarily for N2369, and its corresponding section
20.6.4.1 [uninitialized.copy].
</p>

<p>
It's not clear to me what the return clause is supposed to mean, I see
two
possible interpretations:
</p>

<ol type="a">
<li>
The notion of <tt><i>result</i></tt> is supposed to mean the value given by the
function parameter <tt><i>result</i></tt> [Note to the issue editor: Please use italics for
<tt><i>result</i></tt>].
This seems somewhat implied by recognizing that both the function
parameter
and the name used in the clause do have the same italic font.
</li>
<li>
The notion of "result" is supposed to mean the value of <tt><i>result</i></tt>
after the
preceding effects clause. This is in fact what all implementations I
checked
do (and which is probably it's intend, because it matches the
specification of <tt>std::copy</tt>).
</li>
</ol>

<p>
The problem is: I see nothing in the standard which grants that this
interpretation
is correct, specifically [lib.structure.specifications] or
17.3.1.3 [structure.specifications]
resp. do not clarify which "look-up" rules apply for names found in
the elements
of the detailed specifications - Do they relate to the corresponding
synopsis or
to the effects clause (or possibly other elements)? Fortunately most
detailed
descriptions are unambigious in this regard, e.g. this problem does
not apply
for <tt>std::copy</tt>.
</p>



<p><b>Proposed resolution:</b></p>
<p>
Change the wording of the return clause to say (20.6.4.1 [uninitialized.copy]):
</p>

<blockquote>
<p>
-2- <i>Returns:</i> <ins>The value of</ins> <tt><i>result</i></tt> <ins>after effects have taken place.</ins>
</p>
</blockquote>






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