Markus Armbruster
9645caf6ff
Testing whether the compiler supports it is a bit tricky. The obvious AX_APPEND_COMPILE_FLAGS([-fstack-protector-strong]) doesn't suffice, since some ports of the GNU toolchain reportedly pass this test, then fail to link. That's because the compiler accepts the flag, duly emits references to helper code in libc, but libc doesn't provide, and linking fails. Instead, use AX_APPEND_LINK_FLAGS with an input source that makes the compiler emit the extra stack checking code. This requires the latest version from the autoconf-archive, so update m4/ax* to commit e3d948b. Also update m4/my_append_compile_flags.m4 to keep it in sync with upstream's ax_append_compile_flags.m4. Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
74 lines
3.1 KiB
Text
74 lines
3.1 KiB
Text
# ===========================================================================
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# http://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html
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# ===========================================================================
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#
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# SYNOPSIS
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#
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# AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
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#
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# DESCRIPTION
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#
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# Check whether the given FLAG works with the linker or gives an error.
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# (Warnings, however, are ignored)
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#
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# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
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# success/failure.
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#
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# If EXTRA-FLAGS is defined, it is added to the linker's default flags
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# when the check is done. The check is thus made with the flags: "LDFLAGS
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# EXTRA-FLAGS FLAG". This can for example be used to force the linker to
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# issue an error when a bad flag is given.
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#
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# INPUT gives an alternative input source to AC_LINK_IFELSE.
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#
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# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
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# macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG.
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#
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# LICENSE
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#
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# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
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# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
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#
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# This program is free software: you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation, either version 3 of the License, or (at your
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# option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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# Public License for more details.
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#
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# You should have received a copy of the GNU General Public License along
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# with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# As a special exception, the respective Autoconf Macro's copyright owner
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# gives unlimited permission to copy, distribute and modify the configure
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# scripts that are the output of Autoconf when processing the Macro. You
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# need not follow the terms of the GNU General Public License when using
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# or distributing such scripts, even though portions of the text of the
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# Macro appear in them. The GNU General Public License (GPL) does govern
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# all other use of the material that constitutes the Autoconf Macro.
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#
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# This special exception to the GPL applies to versions of the Autoconf
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# Macro released by the Autoconf Archive. When you make and distribute a
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# modified version of the Autoconf Macro, you may extend this special
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# exception to the GPL to apply to your modified version as well.
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#serial 4
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AC_DEFUN([AX_CHECK_LINK_FLAG],
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[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
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AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl
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AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [
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ax_check_save_flags=$LDFLAGS
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LDFLAGS="$LDFLAGS $4 $1"
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AC_LINK_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
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[AS_VAR_SET(CACHEVAR,[yes])],
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[AS_VAR_SET(CACHEVAR,[no])])
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LDFLAGS=$ax_check_save_flags])
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AS_VAR_IF(CACHEVAR,yes,
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[m4_default([$2], :)],
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[m4_default([$3], :)])
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AS_VAR_POPDEF([CACHEVAR])dnl
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])dnl AX_CHECK_LINK_FLAGS
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