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      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 (a] redhat.com>
     18 #   Copyright (c) 2008 Christian Haggstrom
     19 #   Copyright (c) 2008 Ryan McCabe <ryan (a] 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 ])
     68