ax_gcc_warn_unused_result.m4

# ===========================================================================
#    http://www.nongnu.org/autoconf-archive/ax_gcc_warn_unused_result.html
# ===========================================================================
#
# SYNOPSIS
#
#   AX_GCC_WARN_UNUSED_RESULT
#
# DESCRIPTION
#
#   The macro will compile a test program to see whether the compiler does
#   understand the per-function postfix pragma.
#
# LICENSE
#
#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
#
#   This program is free software; you can redistribute it and/or modify it
#   under the terms of the GNU General Public License as published by the
#   Free Software Foundation; either version 2 of the License, or (at your
#   option) any later version.
#
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#   WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
#   Public License for more details.
#
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#   with this program. If not, see <http://www.gnu.org/licenses/>.
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AC_DEFUN([AX_GCC_WARN_UNUSED_RESULT],[dnl
AC_CACHE_CHECK(
 [whether the compiler supports function __attribute__((__warn_unused_result__))],
 ax_cv_gcc_warn_unused_result,[
 AC_TRY_COMPILE([__attribute__((__warn_unused_result__))
 int f(int i) { return i; }],
 [],
 ax_cv_gcc_warn_unused_result=yes, ax_cv_gcc_warn_unused_result=no)])
 if test "$ax_cv_gcc_warn_unused_result" = yes; then
   AC_DEFINE([GCC_WARN_UNUSED_RESULT],[__attribute__((__warn_unused_result__))],
    [most gcc compilers know a function __attribute__((__warn_unused_result__))])
 fi
])