m4/ax_c___attribute__.m4

   1 # SPDX-License-Identifier: GPL-2.0-or-later WITH LicenseRef-Autoconf-exception-macro
   2 #
   3 # ===========================================================================
   4 #    https://www.gnu.org/software/autoconf-archive/ax_c___attribute__.html
   5 # ===========================================================================
   6 #
   7 # SYNOPSIS
   8 #
   9 #   AX_C___ATTRIBUTE__
  10 #
  11 # DESCRIPTION
  12 #
  13 #   Provides a test for the compiler support of __attribute__ extensions.
  14 #   Defines HAVE___ATTRIBUTE__ if it is found.
  15 #
  16 # LICENSE
  17 #
  18 #   Copyright (c) 2008 Stepan Kasal <skasal@redhat.com>
  19 #   Copyright (c) 2008 Christian Haggstrom
  20 #   Copyright (c) 2008 Ryan McCabe <ryan@numb.org>
  21 #
  22 #   This program is free software; you can redistribute it and/or modify it
  23 #   under the terms of the GNU General Public License as published by the
  24 #   Free Software Foundation; either version 2 of the License, or (at your
  25 #   option) any later version.
  26 #
  27 #   This program is distributed in the hope that it will be useful, but
  28 #   WITHOUT ANY WARRANTY; without even the implied warranty of
  29 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
  30 #   Public License for more details.
  31 #
  32 #   You should have received a copy of the GNU General Public License along
  33 #   with this program. If not, see <https://www.gnu.org/licenses/>.
  34 #
  35 #   As a special exception, the respective Autoconf Macro's copyright owner
  36 #   gives unlimited permission to copy, distribute and modify the configure
  37 #   scripts that are the output of Autoconf when processing the Macro. You
  38 #   need not follow the terms of the GNU General Public License when using
  39 #   or distributing such scripts, even though portions of the text of the
  40 #   Macro appear in them. The GNU General Public License (GPL) does govern
  41 #   all other use of the material that constitutes the Autoconf Macro.
  42 #
  43 #   This special exception to the GPL applies to versions of the Autoconf
  44 #   Macro released by the Autoconf Archive. When you make and distribute a
  45 #   modified version of the Autoconf Macro, you may extend this special
  46 #   exception to the GPL to apply to your modified version as well.
  47
  48 #serial 9
  49
  50 AC_DEFUN([AX_C___ATTRIBUTE__], [
  51   AC_CACHE_CHECK([for __attribute__], [ax_cv___attribute__],
  52     [AC_COMPILE_IFELSE(
  53       [AC_LANG_PROGRAM(
  54         [[#include <stdlib.h>
  55           static void foo(void) __attribute__ ((unused));
  56           static void
  57           foo(void) {
  58               exit(1);
  59           }
  60         ]], [])],
  61       [ax_cv___attribute__=yes],
  62       [ax_cv___attribute__=no]
  63     )
  64   ])
  65   if test "$ax_cv___attribute__" = "yes"; then
  66     AC_DEFINE([HAVE___ATTRIBUTE__], 1, [define if your compiler has __attribute__])
  67   fi
  68 ])