X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=lib%2Fignore-value.h;h=95eac1cae7283d5387e5040e38063156bf80385d;hb=92249085071a973e2c0621b0415b93d2e48bb00d;hp=2eb6918db579a258af4e2046508ea09866c81e1e;hpb=a2016c1de6e4884f6c8ed5cc498f3bf821c25ca4;p=debian%2Fgzip
diff --git a/lib/ignore-value.h b/lib/ignore-value.h
index 2eb6918..95eac1c 100644
--- a/lib/ignore-value.h
+++ b/lib/ignore-value.h
@@ -1,6 +1,6 @@
-/* ignore a function return without a compiler warning
+/* ignore a function return without a compiler warning. -*- coding: utf-8 -*-
- Copyright (C) 2008-2010 Free Software Foundation, Inc.
+ Copyright (C) 2008-2018 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -13,11 +13,11 @@
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program. If not, see . */
+ along with this program. If not, see . */
-/* Written by Jim Meyering. */
+/* Written by Jim Meyering, Eric Blake and Pádraig Brady. */
-/* Use these functions to avoid a warning when using a function declared with
+/* 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,
@@ -32,6 +32,19 @@
"copy.c:233: warning: ignoring return value of 'fchown',
declared with attribute warn_unused_result". */
-static inline void ignore_value (int i) { (void) i; }
-static inline void ignore_ptr (void* p) { (void) p; }
-/* FIXME: what about aggregate types? */
+#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. */
+#if 3 < __GNUC__ + (4 <= __GNUC_MINOR__)
+# define ignore_value(x) \
+ (__extension__ ({ __typeof__ (x) __x = (x); (void) __x; }))
+#else
+# define ignore_value(x) ((void) (x))
+#endif
+
+#endif