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Subject[1/2] Make BUILD_BUG_ON fail at compile time.
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;
-
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