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List:       linux-sparse
Subject:    [PATCH v8 6/9] bug.h: Prevent double evaulation of in BUILD_BUG_ON
From:       danielfsantos () att ! net
Date:       2013-01-01 22:54:08
Message-ID: 1357080851-30938-7-git-send-email-daniel.santos () pobox ! com
[Download RAW message or body]

When calling BUILD_BUG_ON in an optimized build using gcc 4.3 and later,
the condition will be evaulated twice, possibily with side-effects.
This patch eliminates that error.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
---
 include/linux/bug.h |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/bug.h b/include/linux/bug.h
index 27d404f..0d75762 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -59,8 +59,9 @@ struct pt_regs;
 extern int __build_bug_on_failed;
 #define BUILD_BUG_ON(condition)					\
 	do {							\
-		((void)sizeof(char[1 - 2*!!(condition)]));	\
-		if (condition) __build_bug_on_failed = 1;	\
+		bool __cond = !!(condition);			\
+		((void)sizeof(char[1 - 2 * __cond]));		\
+		if (__cond) __build_bug_on_failed = 1;		\
 	} while(0)
 #endif
 
-- 
1.7.8.6

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