From be8efac78d067c138ad8dda03df4336e73f94887 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=B6rg=20Frings-F=C3=BCrst?= Date: Sat, 8 Jan 2022 11:51:07 +0100 Subject: New upstream version 1.0 --- tests/ignore-value.h | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) create mode 100644 tests/ignore-value.h (limited to 'tests/ignore-value.h') 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 . */ + +/* 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 -- cgit v1.2.3