mirror of
https://github.com/libguestfs/libguestfs.git
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0f54df53d2
As part of our efforts to clean up and simplify libguestfs, removing gnulib deletes a large dependency that we mostly no longer use and causes problems for new users trying to build the library from source. A few modules from gnulib are still used (under a compatible license) and these are copied into gnulib/lib/
59 lines
2.6 KiB
C
Executable File
59 lines
2.6 KiB
C
Executable File
/* ignore a function return without a compiler warning. -*- coding: utf-8 -*-
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Copyright (C) 2008-2021 Free Software Foundation, Inc.
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(NB: I modified the original GPL boilerplate here to LGPLv2+. This
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is because of the weird way that gnulib uses licenses, where the
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real license is covered in the modules/X file. The real license
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for this file is LGPLv2+, not GPL. - RWMJ)
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* Written by Jim Meyering, Eric Blake and Pádraig Brady. */
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/* Use "ignore_value" to avoid a warning when using a function declared with
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gcc's warn_unused_result attribute, but for which you really do want to
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ignore the result. Traditionally, people have used a "(void)" cast to
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indicate that a function's return value is deliberately unused. However,
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if the function is declared with __attribute__((warn_unused_result)),
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gcc issues a warning even with the cast.
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Caution: most of the time, you really should heed gcc's warning, and
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check the return value. However, in those exceptional cases in which
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you're sure you know what you're doing, use this function.
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For the record, here's one of the ignorable warnings:
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"copy.c:233: warning: ignoring return value of 'fchown',
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declared with attribute warn_unused_result". */
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#ifndef _GL_IGNORE_VALUE_H
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#define _GL_IGNORE_VALUE_H
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/* Normally casting an expression to void discards its value, but GCC
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versions 3.4 and newer have __attribute__ ((__warn_unused_result__))
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which may cause unwanted diagnostics in that case. Use __typeof__
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and __extension__ to work around the problem, if the workaround is
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known to be needed.
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The workaround is not needed with clang. */
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#if (3 < __GNUC__ + (4 <= __GNUC_MINOR__)) && !defined __clang__
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# define ignore_value(x) \
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(__extension__ ({ __typeof__ (x) __x = (x); (void) __x; }))
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#else
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# define ignore_value(x) ((void) (x))
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#endif
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#endif
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