| 1 | /* ignore a function return without a compiler warning |
| 2 | |
| 3 | Copyright (C) 2008-2011 Free Software Foundation, Inc. |
| 4 | |
| 5 | This program is free software: you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 3 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | /* Written by Jim Meyering, Eric Blake and Pádraig Brady. */ |
| 19 | |
| 20 | /* Use "ignore_value" to avoid a warning when using a function declared with |
| 21 | gcc's warn_unused_result attribute, but for which you really do want to |
| 22 | ignore the result. Traditionally, people have used a "(void)" cast to |
| 23 | indicate that a function's return value is deliberately unused. However, |
| 24 | if the function is declared with __attribute__((warn_unused_result)), |
| 25 | gcc issues a warning even with the cast. |
| 26 | |
| 27 | Caution: most of the time, you really should heed gcc's warning, and |
| 28 | check the return value. However, in those exceptional cases in which |
| 29 | you're sure you know what you're doing, use this function. |
| 30 | |
| 31 | For the record, here's one of the ignorable warnings: |
| 32 | "copy.c:233: warning: ignoring return value of 'fchown', |
| 33 | declared with attribute warn_unused_result". */ |
| 34 | |
| 35 | #ifndef _GL_IGNORE_VALUE_H |
| 36 | # define _GL_IGNORE_VALUE_H |
| 37 | |
| 38 | # ifndef _GL_ATTRIBUTE_DEPRECATED |
| 39 | /* The __attribute__((__deprecated__)) feature |
| 40 | is available in gcc versions 3.1 and newer. */ |
| 41 | # if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 1) |
| 42 | # define _GL_ATTRIBUTE_DEPRECATED /* empty */ |
| 43 | # else |
| 44 | # define _GL_ATTRIBUTE_DEPRECATED __attribute__ ((__deprecated__)) |
| 45 | # endif |
| 46 | # endif |
| 47 | |
| 48 | /* The __attribute__((__warn_unused_result__)) feature |
| 49 | is available in gcc versions 3.4 and newer, |
| 50 | while the typeof feature has been available since 2.7 at least. */ |
| 51 | # if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ < 4) |
| 52 | # define ignore_value(x) ((void) (x)) |
| 53 | # else |
| 54 | # define ignore_value(x) (({ __typeof__ (x) __x = (x); (void) __x; })) |
| 55 | # endif |
| 56 | |
| 57 | /* ignore_value works for scalars, pointers and aggregates; |
| 58 | deprecate ignore_ptr. */ |
| 59 | static inline void _GL_ATTRIBUTE_DEPRECATED |
| 60 | ignore_ptr (void *p) { (void) p; } /* deprecated: use ignore_value */ |
| 61 | |
| 62 | #endif |