From: "Andi Kleen" <ak@suse.de>
To: akpm@osdl.org
Cc: linux-kernel@vger.kernel.org, jbeulich@novell.com
Subject: [1/2] Make BUILD_BUG_ON fail at compile time.
Date: Sat, 10 Sep 2005 14:04:40 +0200 [thread overview]
Message-ID: <4322CBD8.mailE1M1FX8RR@suse.de> (raw)
Make BUILD_BUG_ON fail at compile time.
Force a compiler error instead of a link error, because they
are easier to track down. Idea stolen from code by Jan Beulich.
Cc: jbeulich@novell.com
Index: linux/include/linux/kernel.h
===================================================================
--- linux.orig/include/linux/kernel.h
+++ linux/include/linux/kernel.h
@@ -307,8 +307,8 @@ struct sysinfo {
char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding: libc5 uses this.. */
};
-extern void BUILD_BUG(void);
-#define BUILD_BUG_ON(condition) do { if (condition) BUILD_BUG(); } while(0)
+/* Force a compilation error if condition is false */
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#ifdef CONFIG_SYSCTL
extern int randomize_va_space;
next reply other threads:[~2005-09-10 12:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-10 12:04 Andi Kleen [this message]
2005-09-10 13:22 ` [1/2] Make BUILD_BUG_ON fail at compile time Christoph Hellwig
2005-09-12 18:01 ` Hans Reiser
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