From: "Andi Kleen" <ak@suse.de>
Force a compiler error instead of a link error, because they are easier to
track down. Idea stolen from code by Jan Beulich <jbeulich@novell.com>
If the argument to BUILD_BUG_ON evaluates to non-zero the compiler will do:
t.c:6: error: size of array `type name' is negative
(surprised that gcc doesn't have an extension for this)
Signed-off-by: "Andi Kleen" <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
include/linux/kernel.h | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff -puN include/linux/kernel.h~make-build_bug_on-fail-at-compile-time include/linux/kernel.h
--- devel/include/linux/kernel.h~make-build_bug_on-fail-at-compile-time 2005-09-10 14:37:46.000000000 -0700
+++ devel-akpm/include/linux/kernel.h 2005-09-10 14:37:46.000000000 -0700
@@ -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;
_