imagemagick/m4/ax_c___attribute__.m4

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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_c___attribute__.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_C___ATTRIBUTE__
#
# DESCRIPTION
#
# Provides a test for the compiler support of __attribute__ extensions.
# Defines HAVE___ATTRIBUTE__ if it is found.
#
# LICENSE
#
# Copyright (c) 2008 Stepan Kasal <skasal@redhat.com>
# Copyright (c) 2008 Christian Haggstrom
# Copyright (c) 2008 Ryan McCabe <ryan@numb.org>
#
# 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 2 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 <https://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.
#serial 9
AC_DEFUN([AX_C___ATTRIBUTE__], [
AC_CACHE_CHECK([for __attribute__], [ax_cv___attribute__],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stdlib.h>
static void foo(void) __attribute__ ((unused));
static void
foo(void) {
exit(1);
}
]], [])],
[ax_cv___attribute__=yes],
[ax_cv___attribute__=no]
)
])
if test "$ax_cv___attribute__" = "yes"; then
AC_DEFINE([HAVE___ATTRIBUTE__], 1, [define if your compiler has __attribute__])
fi
])