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author | Jörg Frings-Fürst <debian@jff.email> | 2022-02-07 06:57:44 +0100 |
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committer | Jörg Frings-Fürst <debian@jff.email> | 2022-02-07 06:57:44 +0100 |
commit | 6ffaa52cf732a84c0f8259dbc9b8183960ec5c33 (patch) | |
tree | d3136c22e3e805cfc0efe78412cce905a17e0c8d /tests/ignore-value.h | |
parent | 591cbf5878b7d4105b275585b9db1324c9dfce56 (diff) | |
parent | af151c593704a40e10efb28d1e3dd59a23a661f3 (diff) |
Merge branch 'release/debian/1.0-1'debian/1.0-1
Diffstat (limited to 'tests/ignore-value.h')
-rw-r--r-- | tests/ignore-value.h | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/tests/ignore-value.h b/tests/ignore-value.h new file mode 100644 index 00000000..173b63f5 --- /dev/null +++ b/tests/ignore-value.h @@ -0,0 +1,51 @@ +/* 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 |