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# ===========================================================================
# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
#
# DESCRIPTION
#
# Check whether the given FLAG works with the current language's compiler
# or gives an error. (Warnings, however, are ignored)
#
# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
# success/failure.
#
# If EXTRA-FLAGS is defined, it is added to the current language's default
# flags (e.g. CFLAGS) when the check is done. The check is thus made with
# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to
# force the compiler to issue an error when a bad flag is given.
#
# INPUT gives an alternative input source to AC_COMPILE_IFELSE.
#
# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
#
# LICENSE
#
# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
#
# This program 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 of the License, or (at your
# option) any later version.
#
# This program 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 program. If not, see <http://www.gnu.org/licenses/>.
#
# As a special exception, the respective Autoconf Macro's copyright owner
# gives unlimited permission to copy, distribute and modify the configure
# scripts that are the output of Autoconf when processing the Macro. You
# need not follow the terms of the GNU General Public License when using
# or distributing such scripts, even though portions of the text of the
# Macro appear in them. The GNU General Public License (GPL) does govern
# all other use of the material that constitutes the Autoconf Macro.
#
# This special exception to the GPL applies to versions of the Autoconf
# Macro released by the Autoconf Archive. When you make and distribute a
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
# Emil:
# Toggle Werror since at some point clang started treating unknown -W
# flags as warnings, succeeding with the build, yet issuing an annoying
# warning.
#serial 3
AC_DEFUN([AX_CHECK_COMPILE_FLAG],
[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
_AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1 -Werror"
AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
[AS_VAR_SET(CACHEVAR,[yes])],
[AS_VAR_SET(CACHEVAR,[no])])
_AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes],
[m4_default([$2], :)],
[m4_default([$3], :)])
AS_VAR_POPDEF([CACHEVAR])dnl
])dnl AX_CHECK_COMPILE_FLAGS
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