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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_check_preproc_flag.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_CHECK_PREPROC_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
#
# DESCRIPTION
#
# Check whether the given FLAG works with the current language's
# preprocessor 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 preprocessor's default
# flags when the check is done. The check is thus made with the flags:
# "CPPFLAGS EXTRA-FLAGS FLAG". This can for example be used to force the
# preprocessor to issue an error when a bad flag is given.
#
# INPUT gives an alternative input source to AC_PREPROC_IFELSE.
#
# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
# macro in sync with AX_CHECK_{COMPILE,LINK}_FLAG.
#
# LICENSE
#
# Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
# Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
#
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
#serial 6
AC_DEFUN([AX_CHECK_PREPROC_FLAG],
[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]cppflags_$4_$1])dnl
AC_CACHE_CHECK([whether _AC_LANG preprocessor accepts $1], CACHEVAR, [
ax_check_save_flags=$CPPFLAGS
CPPFLAGS="$CPPFLAGS $4 $1"
AC_PREPROC_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
[AS_VAR_SET(CACHEVAR,[yes])],
[AS_VAR_SET(CACHEVAR,[no])])
CPPFLAGS=$ax_check_save_flags])
AS_VAR_IF(CACHEVAR,yes,
[m4_default([$2], :)],
[m4_default([$3], :)])
AS_VAR_POPDEF([CACHEVAR])dnl
])dnl AX_CHECK_PREPROC_FLAGS
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