gcc/config/no-executables.m4
Richard Sandiford b6f914f633 no-executables.m4 (GCC_TRY_COMPILE_OR_LINK): New function.
config/
	* no-executables.m4 (GCC_TRY_COMPILE_OR_LINK): New function.
	libstdc++-v3/

libstdc++/
	* acinclude.m4 (GLIBCXX_ENABLE_C99): Temporarily add
	-fno-exceptions to CXXFLAGS.  Use GCC_TRY_COMPILE_OR_LINK.
	Make the tests assign results to volatile variables.  Use -lm
	for link tests in GCC_TRY_COMPILE_OR_LINK.  Fall back to
	compile-only tests if -lm is not available.
	* configure: Regenerate.

From-SVN: r128982
2007-10-03 14:16:57 +00:00

70 lines
2.2 KiB
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# GCC_NO_EXECUTABLES
# -----------------
# FIXME: The GCC team has specific needs which the current Autoconf
# framework cannot solve elegantly. This macro implements a dirty
# hack until Autoconf is able to provide the services its users
# need.
#
# Several of the support libraries that are often built with GCC can't
# assume the tool-chain is already capable of linking a program: the
# compiler often expects to be able to link with some of such
# libraries.
#
# In several of these libraries, workarounds have been introduced to
# avoid the AC_PROG_CC_WORKS test, that would just abort their
# configuration. The introduction of AC_EXEEXT, enabled either by
# libtool or by CVS autoconf, have just made matters worse.
#
# Unlike the previous AC_NO_EXECUTABLES, this test does not
# disable link tests at autoconf time, but at configure time.
# This allows AC_NO_EXECUTABLES to be invoked conditionally.
AC_DEFUN_ONCE([GCC_NO_EXECUTABLES],
[m4_divert_push([KILL])
AC_BEFORE([$0], [_AC_COMPILER_EXEEXT])
AC_BEFORE([$0], [AC_LINK_IFELSE])
m4_define([_AC_COMPILER_EXEEXT],
AC_LANG_CONFTEST([AC_LANG_PROGRAM()])
# FIXME: Cleanup?
AS_IF([AC_TRY_EVAL(ac_link)], [gcc_no_link=no], [gcc_no_link=yes])
if test x$gcc_no_link = xyes; then
# Setting cross_compile will disable run tests; it will
# also disable AC_CHECK_FILE but that's generally
# correct if we can't link.
cross_compiling=yes
EXEEXT=
else
m4_defn([_AC_COMPILER_EXEEXT])dnl
fi
)
m4_define([AC_LINK_IFELSE],
if test x$gcc_no_link = xyes; then
AC_MSG_ERROR([Link tests are not allowed after [[$0]].])
fi
m4_defn([AC_LINK_IFELSE]))
dnl This is a shame. We have to provide a default for some link tests,
dnl similar to the default for run tests.
m4_define([AC_FUNC_MMAP],
if test x$gcc_no_link = xyes; then
if test "x${ac_cv_func_mmap_fixed_mapped+set}" != xset; then
ac_cv_func_mmap_fixed_mapped=no
fi
fi
if test "x${ac_cv_func_mmap_fixed_mapped}" != xno; then
m4_defn([AC_FUNC_MMAP])
fi)
m4_divert_pop()dnl
])# GCC_NO_EXECUTABLES
# Use the strongest available test out of AC_TRY_COMPILE and AC_TRY_LINK.
AC_DEFUN([GCC_TRY_COMPILE_OR_LINK],
[if test x$gcc_no_link = xyes; then
AC_TRY_COMPILE([$1], [$2], [$3], [$4])
else
AC_TRY_LINK([$1], [$2], [$3], [$4])
fi])