From 2621048598e9c71a44811add31d8d7530d1ed056 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 27 Jul 2012 09:59:25 +0200 Subject: [PATCH] use C11's _Static_assert() for BUILD_BUG_ON etc when available This produces a more meaningful compiler diagnostic in case it happens to trigger. As a minor piece of cleanup, at once also use BUILD_BUG_ON_ZERO() to actually define BUILD_BUG_ON() in the legacy case, slightly reducing redundancy. Signed-off-by: Jan Beulich Acked-by: Keir Fraser --- xen/include/xen/lib.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h index 36b4c7f12d..1919ed7d93 100644 --- a/xen/include/xen/lib.h +++ b/xen/include/xen/lib.h @@ -14,14 +14,20 @@ void __warn(char *file, int line); #define BUG_ON(p) do { if (unlikely(p)) BUG(); } while (0) #define WARN_ON(p) do { if (unlikely(p)) WARN(); } while (0) +#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) /* Force a compilation error if condition is true */ -#define BUILD_BUG_ON(condition) ((void)sizeof(struct { int:-!!(condition); })) +#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); }) /* Force a compilation error if condition is true, but also produce a result (of value 0 and type size_t), so the expression can be used e.g. in a structure initializer (or where-ever else comma expressions aren't permitted). */ -#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); })) +#define BUILD_BUG_ON_ZERO(cond) \ + sizeof(struct { _Static_assert(!(cond), "!(" #cond ")"); }) +#else +#define BUILD_BUG_ON_ZERO(cond) sizeof(struct { int:-!!(cond); }) +#define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond)) +#endif #ifndef assert_failed #define assert_failed(p) \ -- 2.30.2