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On bare-metal targets, I/O support is typically provided by a BSP and requires a linker script and/or hosting library to be specified on the linker command line. Linking an empty program with the default linker script may succeed, however, which confuses libstdc++ configuration when programs that probe for the presence of various I/O features fail with link errors. 2020-02-12 Sandra Loosemore <sandra@codesourcery.com> PR libstdc++/79193 PR libstdc++/88999 config/ * no-executables.m4: Use a non-empty program to test for linker support. libgcc/ * configure: Regenerated. libgfortran/ * configure: Regenerated. libiberty/ * configure: Regenerated. libitm/ * configure: Regenerated. libobjc/ * configure: Regenerated. libquadmath/ * configure: Regenerated. libssp/ * configure: Regenerated. libstdc++v-3/ * configure: Regenerated.
72 lines
2.3 KiB
Plaintext
72 lines
2.3 KiB
Plaintext
# GCC_NO_EXECUTABLES
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# -----------------
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# FIXME: The GCC team has specific needs which the current Autoconf
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# framework cannot solve elegantly. This macro implements a dirty
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# hack until Autoconf is able to provide the services its users
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# need.
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#
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# Several of the support libraries that are often built with GCC can't
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# assume the tool-chain is already capable of linking a program: the
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# compiler often expects to be able to link with some of such
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# libraries.
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#
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# In several of these libraries, workarounds have been introduced to
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# avoid the AC_PROG_CC_WORKS test, that would just abort their
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# configuration. The introduction of AC_EXEEXT, enabled either by
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# libtool or by CVS autoconf, have just made matters worse.
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#
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# Unlike the previous AC_NO_EXECUTABLES, this test does not
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# disable link tests at autoconf time, but at configure time.
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# This allows AC_NO_EXECUTABLES to be invoked conditionally.
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AC_DEFUN_ONCE([GCC_NO_EXECUTABLES],
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[m4_divert_push([KILL])
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AC_BEFORE([$0], [_AC_COMPILER_EXEEXT])
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AC_BEFORE([$0], [AC_LINK_IFELSE])
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m4_define([_AC_COMPILER_EXEEXT],
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[AC_LANG_CONFTEST([AC_LANG_PROGRAM(
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[#include <stdio.h>],
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[printf ("hello world\n");])])
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# FIXME: Cleanup?
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AS_IF([AC_TRY_EVAL(ac_link)], [gcc_no_link=no], [gcc_no_link=yes])
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if test x$gcc_no_link = xyes; then
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# Setting cross_compile will disable run tests; it will
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# also disable AC_CHECK_FILE but that's generally
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# correct if we can't link.
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cross_compiling=yes
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EXEEXT=
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else
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]m4_defn([_AC_COMPILER_EXEEXT])dnl
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fi
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)
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m4_define([AC_LINK_IFELSE],
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if test x$gcc_no_link = xyes; then
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AC_MSG_ERROR([Link tests are not allowed after [[$0]].])
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fi
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m4_defn([AC_LINK_IFELSE]))
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dnl This is a shame. We have to provide a default for some link tests,
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dnl similar to the default for run tests.
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m4_define([AC_FUNC_MMAP],
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if test x$gcc_no_link = xyes; then
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if test "x${ac_cv_func_mmap_fixed_mapped+set}" != xset; then
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ac_cv_func_mmap_fixed_mapped=no
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fi
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fi
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if test "x${ac_cv_func_mmap_fixed_mapped}" != xno; then
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m4_defn([AC_FUNC_MMAP])
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fi)
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m4_divert_pop()dnl
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])# GCC_NO_EXECUTABLES
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# Use the strongest available test out of AC_TRY_COMPILE and AC_TRY_LINK.
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AC_DEFUN([GCC_TRY_COMPILE_OR_LINK],
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[if test x$gcc_no_link = xyes; then
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AC_TRY_COMPILE([$1], [$2], [$3], [$4])
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else
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AC_TRY_LINK([$1], [$2], [$3], [$4])
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fi])
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