##### http://autoconf-archive.cryp.to/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.
#
# LAST MODIFICATION
#
#   2006-08-10
#
# COPYLEFT
#
#   Copyright (c) 2006 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.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
#   02111-1307, USA.
#
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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
])