@@ -56,13 +56,13 @@ struct pt_regs;
* link-time error, which is harder to track down.
*/
#ifndef __OPTIMIZE__
-#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+#define BUILD_BUG_ON(condition) __compiletime_error_fallback(condition)
#else
#define BUILD_BUG_ON(condition) \
do { \
extern void __build_bug_on_failed(void) \
__compiletime_error("BUILD_BUG_ON failed"); \
- ((void)sizeof(char[1 - 2*!!(condition)])); \
+ __compiletime_error_fallback(condition); \
if (condition) \
__build_bug_on_failed(); \
} while(0)
@@ -298,6 +298,13 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
#endif
#ifndef __compiletime_error
# define __compiletime_error(message)
+# define __compiletime_error_fallback(condition) \
+ do { \
+ ((void)sizeof(char[1 - 2*!!(condition)])); \
+ } while (0)
+#endif
+#ifndef __compiletime_error_fallback
+# define __compiletime_error_fallback(condition) do { } while (0)
#endif
/*
* Prevent the compiler from merging or refetching accesses. The compiler
Prior to the introduction of __attribute__((error("msg"))) in gcc 4.3, creating compile-time errors required a little trickery. BUILD_BUG{,_ON} uses this attribute when available to generate compile-time errors, but also uses the negative-sized array trick for older compilers, resulting in two error messages in some cases. The reason it's "some" cases is that as of gcc 4.4, the negative-sized array will not create an error in some situations, like inline functions. This patch replaces the negative-sized array code with the new __compiletime_error_fallback() macro which expands to the same thing unless the the error attribute is available, in which case it expands to do{}while(0), resulting in exactly one compile-time error on all versions of gcc. Signed-off-by: Daniel Santos <daniel.santos@pobox.com> --- include/linux/bug.h | 4 ++-- include/linux/compiler.h | 7 +++++++ 2 files changed, 9 insertions(+), 2 deletions(-)