Compile time futex syscall detection
[urcu.git] / 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
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41 # This special exception to the GPL applies to versions of the Autoconf
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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 ])
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