path: root/libstdc++-v3/configure.in

# Process this file with autoconf to produce a configure script, like so:
# aclocal && autoconf && autoheader && automake

AC_PREREQ(2.13)
AC_INIT(src/ios.cc)

# This works around the fact that libtool configuration may change LD
# for this particular configuration, but some shells, instead of
# keeping the changes in LD private, export them just because LD is
# exported.  Only used at the end of this file.
ORIGINAL_LD_FOR_MULTILIBS=$LD

PACKAGE=libstdc++
AC_SUBST(PACKAGE)
# For libtool versioning info, format is CURRENT:REVISION:AGE
libtool_VERSION=5:2:0
AC_SUBST(libtool_VERSION)

GLIBCPP_TOPREL_CONFIGURE

# Gets build, host, target, *_vendor, *_cpu, *_os, etc.
#
# You will slowly go insane if you do not grok the following fact:  when
# building v3 as part of the compiler, the top-level /target/ becomes the
# library's /host/.  `configure' then causes --target to default to --host,
# exactly like any other package using autoconf.  Therefore, 'target' and
# 'host' will always be the same.  This makes sense both for native and
# cross compilers, just think about it for a little while.  :-)
#
# Also, if v3 is being configured as part of a cross compiler, the top-level
# configure script will pass the "real" host as $with_cross_host.
#
# AC 2.5x sets target_alias iff the user specified --target, but we use it
# everywhere, so we set it here just to be sure.  In AC 2.13
# AC_CANONICAL_TARGET was known as AC_CANONICAL_SYSTEM.
AC_CANONICAL_SYSTEM
target_alias=${target_alias-$target}
AC_SUBST(target_alias)

# Runs configure.target, finds CC, CXX and assorted other critical bits.
# Must run this before the GLIBCPP_ENABLE_* macros below.
GLIBCPP_CONFIGURE(.)

AM_INIT_AUTOMAKE($PACKAGE, $gcc_version)
AM_CONFIG_HEADER(config.h)

AC_LIBTOOL_DLOPEN
AM_PROG_LIBTOOL
AC_SUBST(enable_shared)
AC_SUBST(enable_static)

# Check for c++ or library specific bits that don't require linking.
#GLIBCPP_CHECK_COMPILER_VERSION
GLIBCPP_CHECK_GNU_MAKE

# Enable all the variable C++ stuff.  C_MBCHAR must come early.
GLIBCPP_ENABLE_DEBUG($USE_MAINTAINER_MODE)
GLIBCPP_ENABLE_CSTDIO
GLIBCPP_ENABLE_CLOCALE
GLIBCPP_ENABLE_C_MBCHAR([yes])
GLIBCPP_ENABLE_C99([yes])
GLIBCPP_ENABLE_LONG_LONG([yes])
GLIBCPP_ENABLE_CHEADERS([$c_model])
GLIBCPP_ENABLE_THREADS
GLIBCPP_ENABLE_CXX_FLAGS([none])
GLIBCPP_ENABLE_SJLJ_EXCEPTIONS
GLIBCPP_ENABLE_LIBUNWIND_EXCEPTIONS
GLIBCPP_ENABLE_CONCEPT_CHECKS

# Check for headers necessary for libsupc++ using dyn-string.c/cxa_demangle.c
AC_CHECK_HEADERS(string.h stdlib.h)

# No surprises, no surprises...
if test $ATOMICITYH = cpu/generic ; then
  AC_MSG_WARN([No native atomic operations are provided yet for this platform.])
  if test $target_thread_file = single; then
    AC_MSG_WARN([They cannot be faked when thread support is disabled.])
    AC_MSG_WARN([Thread-safety of certain classes is not guaranteed.])
  else
    AC_MSG_WARN([They will be faked using a mutex.])
    AC_MSG_WARN([Performance of certain classes will degrade as a result.])
  fi
fi


if test -n "$with_cross_host" || test x"$build" != x"$host"; then

  # We are being configured with some form of cross compiler.
  GLIBCPP_IS_CROSS_COMPILING=1

  # This lets us hard-code the functionality we know we'll have in the cross
  # target environment.  "Let" is a sugar-coated word placed on an especially
  # dull and tedious hack, actually.
  #
  # Here's why GLIBCPP_CHECK_MATH_SUPPORT, and other autoconf macros
  # that involve linking, can't be used:
  #    "cannot open sim-crt0.o"
  #    "cannot open crt0.o"
  # etc.  All this is because there currently exists no unified, consistent
  # way for top level CC information to be passed down to target directories:
  # newlib includes, newlib linking info, libgloss versus newlib crt0.o, etc.
  # When all of that is done, all of this hokey, excessive AC_DEFINE junk for
  # crosses can be removed.

  # If Canadian cross, then don't pick up tools from the build directory.
  # Used in GLIBCPP_EXPORT_INCLUDES (and nowhere else?).
  if test -n "$with_cross_host" && test x"$build" != x"$with_cross_host"; then
    CANADIAN=yes
  else
    CANADIAN=no
  fi

  # Construct crosses by hand, eliminating bits that need ld...
  # GLIBCPP_CHECK_COMPILER_FEATURES
  # GLIBCPP_CHECK_BUILTIN_MATH_SUPPORT
  # GLIBCPP_CHECK_MATH_SUPPORT

  case "$target" in
    *-linux*)
      os_include_dir="os/gnu-linux"
      AC_CHECK_HEADERS([nan.h ieeefp.h endian.h sys/isa_defs.h \
        machine/endian.h machine/param.h sys/machine.h sys/types.h \
        fp.h locale.h float.h inttypes.h])
      SECTION_FLAGS='-ffunction-sections -fdata-sections'
      AC_SUBST(SECTION_FLAGS)
      GLIBCPP_CHECK_LINKER_FEATURES
      GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
      GLIBCPP_CHECK_WCHAR_T_SUPPORT
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_FINITE)
      AC_DEFINE(HAVE_FINITEF)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_HYPOTF)
      AC_DEFINE(HAVE_ISINF)
      AC_DEFINE(HAVE_ISINFF)
      AC_DEFINE(HAVE_ISNAN)
      AC_DEFINE(HAVE_ISNANF)
      AC_DEFINE(HAVE_SINCOS)
      AC_DEFINE(HAVE_SINCOSF)
      if test x"long_double_math_on_this_cpu" = x"yes"; then
        AC_DEFINE(HAVE_FINITEL)
        AC_DEFINE(HAVE_HYPOTL)
        AC_DEFINE(HAVE_ISINFL)
        AC_DEFINE(HAVE_ISNANL)
      fi
      ;;
    *-hpux*)
      # Check for available headers.
      AC_CHECK_HEADERS([nan.h ieeefp.h endian.h sys/isa_defs.h \
        machine/endian.h machine/param.h sys/machine.h sys/types.h \
        fp.h locale.h float.h inttypes.h])
      SECTION_FLAGS='-ffunction-sections -fdata-sections'
      AC_SUBST(SECTION_FLAGS)
      GLIBCPP_CHECK_LINKER_FEATURES
      GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
      GLIBCPP_CHECK_WCHAR_T_SUPPORT
      os_include_dir="os/hpux"
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_HYPOT)
      case "$target" in
        *-hpux10*)
          AC_DEFINE(HAVE_FINITE)
          AC_DEFINE(HAVE_FINITEF)
          AC_DEFINE(HAVE_ISINF)
          AC_DEFINE(HAVE_ISINFF)
          AC_DEFINE(HAVE_ISNAN)
          AC_DEFINE(HAVE_ISNANF)
          ;;
      esac

      ;;
    *-netbsd*)
      # Check for available headers.
      AC_CHECK_HEADERS([nan.h ieeefp.h endian.h sys/isa_defs.h \
        machine/endian.h machine/param.h sys/machine.h sys/types.h \
        fp.h locale.h float.h inttypes.h])
      SECTION_FLAGS='-ffunction-sections -fdata-sections'
      AC_SUBST(SECTION_FLAGS) 
      GLIBCPP_CHECK_LINKER_FEATURES
      GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
      GLIBCPP_CHECK_WCHAR_T_SUPPORT
      os_include_dir="os/bsd/netbsd"
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_FINITEF)
      AC_DEFINE(HAVE_FINITE)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_HYPOTF)
      AC_DEFINE(HAVE_ISINF)
      AC_DEFINE(HAVE_ISINFF)
      AC_DEFINE(HAVE_ISNAN)
      AC_DEFINE(HAVE_ISNANF)
      if test x"long_double_math_on_this_cpu" = x"yes"; then
        AC_DEFINE(HAVE_FINITEL)
        AC_DEFINE(HAVE_ISINFL)
        AC_DEFINE(HAVE_ISNANL)
      fi
      ;;
    *-freebsd*)
      # Check for available headers.
      AC_CHECK_HEADERS([nan.h ieeefp.h endian.h sys/isa_defs.h \
        machine/endian.h machine/param.h sys/machine.h sys/types.h \
        fp.h locale.h float.h inttypes.h sys/resource.h sys/stat.h \
        sys/time.h unistd.h])
      SECTION_FLAGS='-ffunction-sections -fdata-sections'
      AC_SUBST(SECTION_FLAGS) 
      GLIBCPP_CHECK_LINKER_FEATURES
      GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
      GLIBCPP_CHECK_WCHAR_T_SUPPORT
      os_include_dir="os/bsd/freebsd"
      AC_DEFINE(HAVE_LC_MESSAGES)
      AC_DEFINE(HAVE_DRAND48)
      AC_DEFINE(HAVE_GETPAGESIZE)
      AC_DEFINE(HAVE_SETENV)
      AC_DEFINE(HAVE_SIGSETJMP)
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_FINITEF)
      AC_DEFINE(HAVE_FINITE)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_HYPOT)
      AC_DEFINE(HAVE_HYPOTF)
      AC_DEFINE(HAVE_ISINF)
      AC_DEFINE(HAVE_ISNAN)
      AC_DEFINE(HAVE_ISNANF)
      if test x"long_double_math_on_this_cpu" = x"yes"; then
        AC_DEFINE(HAVE_FINITEL)
        AC_DEFINE(HAVE_ISINFL)
        AC_DEFINE(HAVE_ISNANL)
      fi
      ;;
    *-mingw32*)
      AC_CHECK_HEADERS([sys/types.h locale.h float.h])
      GLIBCPP_CHECK_LINKER_FEATURES
      GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
      GLIBCPP_CHECK_WCHAR_T_SUPPORT
      os_include_dir="os/mingw32"
      ;;
    *-windiss*)
      os_include_dir="os/windiss"
      ;;
changequote(,)dnl
    *-qnx6.[12]*)
changequote([,])dnl
      SECTION_FLAGS='-ffunction-sections -fdata-sections'
      AC_SUBST(SECTION_FLAGS) 
      GLIBCPP_CHECK_LINKER_FEATURES
      GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
      GLIBCPP_CHECK_WCHAR_T_SUPPORT
      os_include_dir="os/qnx/qnx6.1"
      AC_DEFINE(HAVE_COSF)
      AC_DEFINE(HAVE_COSL)
      AC_DEFINE(HAVE_COSHF)
      AC_DEFINE(HAVE_COSHL)
      AC_DEFINE(HAVE_LOGF)
      AC_DEFINE(HAVE_LOGL)
      AC_DEFINE(HAVE_LOG10F)
      AC_DEFINE(HAVE_LOG10L)
      AC_DEFINE(HAVE_SINF)
      AC_DEFINE(HAVE_SINL)
      AC_DEFINE(HAVE_SINHF)
      AC_DEFINE(HAVE_SINHL)
      ;;
    *)
      os_include_dir="os/newlib"
      AC_DEFINE(HAVE_HYPOT)
      ;;
  esac

  case "$target" in
    *-mingw32*)
      ;;
    *-windiss*)
      AC_DEFINE(HAVE_ACOSF)
      AC_DEFINE(HAVE_ASINF)
      AC_DEFINE(HAVE_ATAN2F)
      AC_DEFINE(HAVE_ATANF)
      AC_DEFINE(HAVE_CEILF)
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_COSF)
      AC_DEFINE(HAVE_COSHF)
      AC_DEFINE(HAVE_EXPF)
      AC_DEFINE(HAVE_FABSF)
      AC_DEFINE(HAVE_FLOORF)
      AC_DEFINE(HAVE_FMODF)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_LDEXPF)
      AC_DEFINE(HAVE_LOG10F)
      AC_DEFINE(HAVE_LOGF)
      AC_DEFINE(HAVE_MODFF)
      AC_DEFINE(HAVE_POWF)
      AC_DEFINE(HAVE_SINF)
      AC_DEFINE(HAVE_SINHF)
      AC_DEFINE(HAVE_SQRTF)
      AC_DEFINE(HAVE_TANF)
      AC_DEFINE(HAVE_TANHF)
      ;;
    *-freebsd*)
      # Must replicate generic section since we don't have strtof or strtold.
      AC_DEFINE(HAVE_MMAP)
      AC_DEFINE(HAVE_ACOSF)
      AC_DEFINE(HAVE_ASINF)
      AC_DEFINE(HAVE_ATAN2F)
      AC_DEFINE(HAVE_ATANF)
      AC_DEFINE(HAVE_CEILF)
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_COSF)
      AC_DEFINE(HAVE_COSHF)
      AC_DEFINE(HAVE_EXPF)
      AC_DEFINE(HAVE_FABSF)
      AC_DEFINE(HAVE_FLOORF)
      AC_DEFINE(HAVE_FMODF)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_LDEXPF)
      AC_DEFINE(HAVE_LOG10F)
      AC_DEFINE(HAVE_LOGF)
      AC_DEFINE(HAVE_MODFF)
      AC_DEFINE(HAVE_POWF)
      AC_DEFINE(HAVE_SINF)
      AC_DEFINE(HAVE_SINHF)
      AC_DEFINE(HAVE_SQRTF)
      AC_DEFINE(HAVE_TANF)
      AC_DEFINE(HAVE_TANHF)
      ;;
    *)
      # GLIBCPP_CHECK_STDLIB_SUPPORT
      AC_DEFINE(HAVE_STRTOF)        
      AC_DEFINE(HAVE_STRTOLD)        
      # AC_FUNC_MMAP
      AC_DEFINE(HAVE_MMAP)

      AC_DEFINE(HAVE_ACOSF)
      AC_DEFINE(HAVE_ASINF)
      AC_DEFINE(HAVE_ATAN2F)
      AC_DEFINE(HAVE_ATANF)
      AC_DEFINE(HAVE_CEILF)
      AC_DEFINE(HAVE_COPYSIGN)
      AC_DEFINE(HAVE_COPYSIGNF)
      AC_DEFINE(HAVE_COSF)
      AC_DEFINE(HAVE_COSHF)
      AC_DEFINE(HAVE_EXPF)
      AC_DEFINE(HAVE_FABSF)
      AC_DEFINE(HAVE_FLOORF)
      AC_DEFINE(HAVE_FMODF)
      AC_DEFINE(HAVE_FREXPF)
      AC_DEFINE(HAVE_LDEXPF)
      AC_DEFINE(HAVE_LOG10F)
      AC_DEFINE(HAVE_LOGF)
      AC_DEFINE(HAVE_MODFF)
      AC_DEFINE(HAVE_POWF)
      AC_DEFINE(HAVE_SINF)
      AC_DEFINE(HAVE_SINHF)
      AC_DEFINE(HAVE_SQRTF)
      AC_DEFINE(HAVE_TANF)
      AC_DEFINE(HAVE_TANHF)
      ;;
  esac

  # At some point, we should differentiate between architectures
  # like x86, which have long double versions, and alpha/powerpc/etc.,
  # which don't. For the time being, punt.
  if test x"long_double_math_on_this_cpu" = x"yes"; then
    AC_DEFINE(HAVE_ACOSL)
    AC_DEFINE(HAVE_ASINL)
    AC_DEFINE(HAVE_ATAN2L)
    AC_DEFINE(HAVE_ATANL)
    AC_DEFINE(HAVE_CEILL)
    AC_DEFINE(HAVE_COPYSIGNL)
    AC_DEFINE(HAVE_COSL)
    AC_DEFINE(HAVE_COSHL)
    AC_DEFINE(HAVE_EXPL)
    AC_DEFINE(HAVE_FABSL)
    AC_DEFINE(HAVE_FLOORL)
    AC_DEFINE(HAVE_FMODL)
    AC_DEFINE(HAVE_FREXPL)
    AC_DEFINE(HAVE_LDEXPL)
    AC_DEFINE(HAVE_LOG10L)
    AC_DEFINE(HAVE_LOGL)
    AC_DEFINE(HAVE_MODFL)
    AC_DEFINE(HAVE_POWL)
    AC_DEFINE(HAVE_SINCOSL)
    AC_DEFINE(HAVE_SINL)
    AC_DEFINE(HAVE_SINHL)
    AC_DEFINE(HAVE_SQRTL)
    AC_DEFINE(HAVE_TANL)
    AC_DEFINE(HAVE_TANHL)
  fi

else

  # We are being configured natively. We can do more elaborate tests
  # that include AC_TRY_COMPILE now, as the linker is assumed to be
  # working.
  GLIBCPP_IS_CROSS_COMPILING=0
  CANADIAN=no

  # Check for available headers.
  AC_CHECK_HEADERS([nan.h ieeefp.h endian.h sys/isa_defs.h machine/endian.h \
  machine/param.h sys/machine.h fp.h locale.h float.h inttypes.h gconv.h sys/types.h])

  GLIBCPP_CHECK_COMPILER_FEATURES
  GLIBCPP_CHECK_LINKER_FEATURES
  GLIBCPP_CHECK_BUILTIN_MATH_SUPPORT
  GLIBCPP_CHECK_MATH_SUPPORT
  GLIBCPP_CHECK_COMPLEX_MATH_SUPPORT
  GLIBCPP_CHECK_WCHAR_T_SUPPORT
  GLIBCPP_CHECK_STDLIB_SUPPORT
  GLIBCPP_CHECK_UNISTD_SUPPORT
  AC_LC_MESSAGES

  AC_TRY_COMPILE([
  #include <setjmp.h>
  ], [sigjmp_buf env; while (! sigsetjmp (env, 1)) siglongjmp (env, 1);],
  [AC_DEFINE(HAVE_SIGSETJMP, 1, [Define if sigsetjmp is available.  ])
  ])

  AC_FUNC_MMAP

  # Establish limits on memory usage during 'make check'
  GLIBCPP_CONFIGURE_TESTSUITE
fi

# This depends on the possibly-skipped linker test above.
GLIBCPP_ENABLE_SYMVERS([yes])

# Propagate the target-specific source directories through the build chain.
# (Nothing currently uses cpu_include_dir directly; only ATOMICITYH 
# uses it, and it only gets used in this file.)
OS_INC_SRCDIR=config/${os_include_dir}
ATOMICITY_INC_SRCDIR=config/${ATOMICITYH}
AC_SUBST(OS_INC_SRCDIR)
AC_SUBST(ATOMICITY_INC_SRCDIR)

# Set up cross-compile flags
AC_SUBST(GLIBCPP_IS_CROSS_COMPILING)  dnl Unused so far.
AM_CONDITIONAL(CANADIAN, test "$CANADIAN" = yes)
 
AC_CACHE_SAVE

if test "${multilib}" = "yes"; then
  multilib_arg="--enable-multilib"
else
  multilib_arg=
fi

# Export all the install information
GLIBCPP_EXPORT_INSTALL_INFO

# Export all the include and flag information to makefiles.
GLIBCPP_EXPORT_INCLUDES
GLIBCPP_EXPORT_FLAGS

if ${CONFIG_SHELL-/bin/sh} ./libtool --tag CXX --features |
   grep "enable shared" > /dev/null; then
  LIBSUPCXX_PICFLAGS=-prefer-pic
else
  LIBSUPCXX_PICFLAGS=
fi
AC_SUBST(LIBSUPCXX_PICFLAGS)

# Generate the various Makefiles, include files, and scripts.
# NB: Multilibs need MULTISUBDIR defined correctly in src/Makefile.am
# and libsupc++/Makefile.am so that multilib installs will end up
# installed in the correct place. To work around this not being passed
# down from config-ml.in -> top_srcdir/Makefile.am ->
# top_srcdir/{src,libsupc++}/Makefile.am, manually append it here.
AC_OUTPUT(Makefile \
    include/Makefile src/Makefile \
    libmath/Makefile libio/Makefile libsupc++/Makefile \
    po/Makefile testsuite/Makefile mkcheck testsuite_flags,
[if test -n "$CONFIG_FILES"; then
  LD="${ORIGINAL_LD_FOR_MULTILIBS}"
  ac_file=Makefile . ${glibcpp_basedir}/../config-ml.in
  grep '^MULTISUBDIR =' Makefile >> src/Makefile
  grep '^MULTISUBDIR =' Makefile >> libsupc++/Makefile
fi
chmod +x mkcheck
chmod +x testsuite_flags
],
srcdir=${srcdir}
host=${host}
target=${target}
with_multisubdir=${with_multisubdir}
ac_configure_args="${multilib_arg} ${ac_configure_args}"
CONFIG_SHELL=${CONFIG_SHELL-/bin/sh}
glibcpp_basedir=${glibcpp_basedir}
CC="${CC}"
CXX="${CXX}"
)
dnl  In autoconf 2.5x, AC_OUTPUT is replaced by three AC_ macros:
dnl  AC_CONFIG_FILES(Makefile \
dnl      include/Makefile src/Makefile \
dnl      libmath/Makefile libio/Makefile libsupc++/Makefile \
dnl      po/Makefile testsuite/Makefile mkcheck testsuite_flags)
dnl  AC_CONFIG_COMMANDS([default],
dnl  [if test -n "$CONFIG_FILES"; then
dnl    ac_file=Makefile . ${glibcpp_basedir}/../config-ml.in
dnl    grep '^MULTISUBDIR =' Makefile >> src/Makefile
dnl    grep '^MULTISUBDIR =' Makefile >> libsupc++/Makefile
dnl  fi
dnl  chmod +x mkcheck
dnl  chmod +x testsuite_flags
dnl  ],
dnl  srcdir=${srcdir}
dnl  host=${host}
dnl  target=${target}
dnl  with_multisubdir=${with_multisubdir}
dnl  ac_configure_args="${multilib_arg} ${ac_configure_args}"
dnl  CONFIG_SHELL=${CONFIG_SHELL-/bin/sh}
dnl  glibcpp_basedir=${glibcpp_basedir}
dnl  CC="${CC}"
dnl  CXX="${CXX}"
dnl  )
dnl  AC_OUTPUT


# Sanity checking & User-visible messages.
# Checks down here, otherwise they get scrolled off before
# the user will notice.

# Trying to get more people to read documentation.  Possibly remove
# check and warn all the time. There is no "informational" AC_MSG_
# macro, so these are going to be printed even when --quiet/--silent
# is given.
if test ! -f stamp-sanity-warned; then
  touch stamp-sanity-warned
  echo ""
  echo "Please make certain that you read the installation information here:"
  echo "  faster => ${srcdir}/docs/html/install.html"
  echo "  slower => <URL:http://gcc.gnu.org/onlinedocs/libstdc++/install.html>"
  echo ""
  echo "and the configuration information here:"
  echo "  faster => ${srcdir}/docs/html/configopts.html"
  echo "  slower => <URL:http://gcc.gnu.org/onlinedocs/libstdc++/configopts.html>"
  echo ""
  echo "before proceeding with ${_cv_gnu_make_command}."
  echo ""
fi