summaryrefslogtreecommitdiff
path: root/lib/ignore-value.h
diff options
context:
space:
mode:
authorRichard Maw <richard.maw@codethink.co.uk>2012-01-17 14:43:55 +0000
committerRichard Maw <richard.maw@codethink.co.uk>2012-01-17 14:43:55 +0000
commit2de9abc5c9d40b3c716307d67d16146f823fd554 (patch)
tree6979db67934ddc8b564150b465846a383b428ff8 /lib/ignore-value.h
parent33cc1c6fda6e72a7bae1401e9b2cec495a4d3ff1 (diff)
downloadpatch-baserock/bootstrap.tar.gz
Diffstat (limited to 'lib/ignore-value.h')
-rw-r--r--lib/ignore-value.h62
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/ignore-value.h b/lib/ignore-value.h
new file mode 100644
index 0000000..f021a1a
--- /dev/null
+++ b/lib/ignore-value.h
@@ -0,0 +1,62 @@
+/* ignore a function return without a compiler warning
+
+ Copyright (C) 2008-2011 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
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but 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, see <http://www.gnu.org/licenses/>. */
+
+/* Written by Jim Meyering, Eric Blake and Pádraig Brady. */
+
+/* Use "ignore_value" to avoid a warning when using a function declared with
+ gcc's warn_unused_result attribute, but for which you really do want to
+ ignore the result. Traditionally, people have used a "(void)" cast to
+ indicate that a function's return value is deliberately unused. However,
+ if the function is declared with __attribute__((warn_unused_result)),
+ gcc issues a warning even with the cast.
+
+ Caution: most of the time, you really should heed gcc's warning, and
+ check the return value. However, in those exceptional cases in which
+ you're sure you know what you're doing, use this function.
+
+ For the record, here's one of the ignorable warnings:
+ "copy.c:233: warning: ignoring return value of 'fchown',
+ declared with attribute warn_unused_result". */
+
+#ifndef _GL_IGNORE_VALUE_H
+# define _GL_IGNORE_VALUE_H
+
+# ifndef _GL_ATTRIBUTE_DEPRECATED
+/* The __attribute__((__deprecated__)) feature
+ is available in gcc versions 3.1 and newer. */
+# if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
+# define _GL_ATTRIBUTE_DEPRECATED /* empty */
+# else
+# define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__))
+# endif
+# endif
+
+/* 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
+
+/* ignore_value works for scalars, pointers and aggregates;
+ deprecate ignore_ptr. */
+static inline void _GL_ATTRIBUTE_DEPRECATED
+ignore_ptr (void *p) { (void) p; } /* deprecated: use ignore_value */
+
+#endif