m4/ax_c___attribute__.m4

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