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      1 # ==============================================================================
      2 #  https://www.gnu.org/software/autoconf-archive/ax_gcc_warn_unused_result.html
      3 # ==============================================================================
      4 #
      5 # SYNOPSIS
      6 #
      7 #   AX_GCC_WARN_UNUSED_RESULT
      8 #
      9 # DESCRIPTION
     10 #
     11 #   The macro will compile a test program to see whether the compiler does
     12 #   understand the per-function postfix pragma.
     13 #
     14 # LICENSE
     15 #
     16 #   Copyright (c) 2008 Guido U. Draheim <guidod (a] gmx.de>
     17 #
     18 #   Copying and distribution of this file, with or without modification, are
     19 #   permitted in any medium without royalty provided the copyright notice
     20 #   and this notice are preserved.  This file is offered as-is, without any
     21 #   warranty.
     22 
     23 #serial 10
     24 
     25 AC_DEFUN([AX_GCC_WARN_UNUSED_RESULT],[dnl
     26 AC_CACHE_CHECK(
     27  [whether the compiler supports function __attribute__((__warn_unused_result__))],
     28  ax_cv_gcc_warn_unused_result,[
     29  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[__attribute__((__warn_unused_result__))
     30  int f(int i) { return i; }]],
     31  [])],
     32  [ax_cv_gcc_warn_unused_result=yes], [ax_cv_gcc_warn_unused_result=no])])
     33  if test "$ax_cv_gcc_warn_unused_result" = yes; then
     34    AC_DEFINE([GCC_WARN_UNUSED_RESULT],[__attribute__((__warn_unused_result__))],
     35     [most gcc compilers know a function __attribute__((__warn_unused_result__))])
     36  fi
     37 ])
     38