-/* ignore a function return without a compiler warning
+/* ignore a function return without a compiler warning. -*- coding: utf-8 -*-
- Copyright (C) 2008-2012 Free Software Foundation, Inc.
+ Copyright (C) 2008-2016 Free Software Foundation, Inc.
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
declared with attribute warn_unused_result". */
#ifndef _GL_IGNORE_VALUE_H
-# define _GL_IGNORE_VALUE_H
-
-/* The __attribute__((__warn_unused_result__)) feature
- is available in gcc versions 3.4 and newer,
- while the typeof feature has been available since 2.7 at least. */
-# if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
-# define ignore_value(x) ((void) (x))
-# else
-# define ignore_value(x) (({ __typeof__ (x) __x = (x); (void) __x; }))
-# endif
+#define _GL_IGNORE_VALUE_H
+
+/* Normally casting an expression to void discards its value, but GCC
+ versions 3.4 and newer have __attribute__ ((__warn_unused_result__))
+ which may cause unwanted diagnostics in that case. Use __typeof__
+ and __extension__ to work around the problem, if the workaround is
+ known to be needed. */
+#if 3 < __GNUC__ + (4 <= __GNUC_MINOR__)
+# define ignore_value(x) \
+ (__extension__ ({ __typeof__ (x) __x = (x); (void) __x; }))
+#else
+# define ignore_value(x) ((void) (x))
+#endif
#endif