m4/ax_c___attribute__.m4

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