Add non-const overload of std::string::data()

Also fix confusion between pointer and _CharT*, so that allocators with
fancy pointers work correctly.

	* include/bits/basic_string.h [_GLIBCXX_USE_CXX11_ABI] (_M_c_str):
	New function.
	(_M_disjunct, basic_string(const basic_string&, size_t)): Use data()
	instead of _M_data().
	(basic_string(const basic_string&, size_t, size_t, const _Alloc&)):
	Likewise.
	(append(const basic_string&)): Likewise.
	(append(const basic_string&, size_type, size_type)): Likewise.
	(assign(const basic_string&, size_type, size_type)): Likewise.
	(insert(size_type, const basic_string&)): Likewise.
	(insert(size_type, const basic_string&, size_type, size_type)):
	Likewise.
	(replace(size_type, size_type, const basic_string&, size_type,
	size_type)): Likewise.
	(replace(__const_iterator, __const_iterator, const basic_string&)):
	Likewise.
	(c_str(), data()): Use c_str() instead of _M_data().
	(data()): Add non-const overload as per LWG 2391 and P0272R1.
	(compare(const basic_string&)): Use data() instead of _M_data().
	[!_GLIBCXX_USE_CXX11_ABI] (data()): Add non-const overload.
	* include/bits/basic_string.tcc [_GLIBCXX_USE_CXX11_ABI] (_M_mutate):
	Pass raw pointers to _S_copy.
	(_M_erase, _M_replace_aux): Pass raw pointers to _S_move and
	_S_assign.
	(find(const _CharT*, size_type, size_type)): Use data instead of
	_M_data().
	* testsuite/21_strings/basic_string/allocator/char/ext_ptr.cc: New.
	* testsuite/21_strings/basic_string/operations/data/char/2.cc: New.
	* testsuite/21_strings/basic_string/operations/data/wchar_t/2.cc: New.

git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@238291 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 80 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/data/char/2.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/data/char/2.cc
new file mode 100644
index 00000000000..046780df410
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/data/char/2.cc
@@ -0,0 +1,40 @@
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+
+// 21.3.1.7 [string.ops] string operations
+
+#include <string>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  std::string s;
+  char* p = s.data();
+  VERIFY( *p == '\0' );
+  s = "a string that is longer than a short string";
+  p = s.data();
+  VERIFY( p == &s.front() );
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/21_strings/basic_string/operations/data/wchar_t/2.cc b/libstdc++-v3/testsuite/21_strings/basic_string/operations/data/wchar_t/2.cc
new file mode 100644
index 00000000000..d4a3206d3b2
--- /dev/null
+++ b/libstdc++-v3/testsuite/21_strings/basic_string/operations/data/wchar_t/2.cc
@@ -0,0 +1,40 @@
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+
+// 21.3.1.7 [string.ops] string operations
+
+#include <string>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  std::wstring s;
+  wchar_t* p = s.data();
+  VERIFY( *p == L'\0' );
+  s = L"a string that is longer than a short string";
+  p = s.data();
+  VERIFY( p == &s.front() );
+}
+
+int
+main()
+{
+  test01();
+}