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authorJörg Frings-Fürst <debian@jff.email>2022-02-07 06:57:44 +0100
committerJörg Frings-Fürst <debian@jff.email>2022-02-07 06:57:44 +0100
commit6ffaa52cf732a84c0f8259dbc9b8183960ec5c33 (patch)
treed3136c22e3e805cfc0efe78412cce905a17e0c8d /tests/ignore-value.h
parent591cbf5878b7d4105b275585b9db1324c9dfce56 (diff)
parentaf151c593704a40e10efb28d1e3dd59a23a661f3 (diff)
Merge branch 'release/debian/1.0-1'debian/1.0-1
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+/* ignore a function return without a compiler warning. -*- coding: utf-8 -*-
+
+ Copyright (C) 2008-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file 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 Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://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
+
+/* 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.
+ The workaround is not needed with clang. */
+#if (3 < __GNUC__ + (4 <= __GNUC_MINOR__)) && !defined __clang__
+# define ignore_value(x) \
+ (__extension__ ({ __typeof__ (x) __x = (x); (void) __x; }))
+#else
+# define ignore_value(x) ((void) (x))
+#endif
+
+#endif