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[Emacs-diffs] /srv/bzr/emacs/trunk r103106: * lib/ignore-value.h: New fi
From: |
Paul Eggert |
Subject: |
[Emacs-diffs] /srv/bzr/emacs/trunk r103106: * lib/ignore-value.h: New file. |
Date: |
Thu, 03 Feb 2011 13:38:34 -0800 |
User-agent: |
Bazaar (2.0.3) |
------------------------------------------------------------
revno: 103106 [merge]
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Thu 2011-02-03 13:38:34 -0800
message:
* lib/ignore-value.h: New file.
added:
lib/ignore-value.h
modified:
ChangeLog
=== modified file 'ChangeLog'
--- a/ChangeLog 2011-02-03 19:29:35 +0000
+++ b/ChangeLog 2011-02-03 21:38:05 +0000
@@ -3,6 +3,7 @@
allow C code to suppress warnings about ignored return values
* Makefile.in (GNULIB_MODULES): Add ignore-value.
* configure, lib/Makefile.in, lib/gnulib.mk, m4/gl-comp.m4: Regenerate.
+ * lib/ignore-value.h: New file.
2011-01-31 Chong Yidong <address@hidden>
=== added file 'lib/ignore-value.h'
--- a/lib/ignore-value.h 1970-01-01 00:00:00 +0000
+++ b/lib/ignore-value.h 2011-02-03 21:38:05 +0000
@@ -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 ATTRIBUTE_DEPRECATED
+/* The __attribute__((__deprecated__)) feature
+ is available in gcc versions 3.1 and newer. */
+# if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1)
+# define ATTRIBUTE_DEPRECATED /* empty */
+# else
+# define 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 ATTRIBUTE_DEPRECATED
+ignore_ptr (void *p) { (void) p; } /* deprecated: use ignore_value */
+
+#endif
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