Introduce __must_be_array

Cloning the similar construct from Linux, allowing to detect improper
uses of ARRAY_SIZE() at build time.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index f5c21f64f7..ab76120da6 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -18,6 +18,12 @@ void __warn(char *file, int line);
 /* Force a compilation error if condition is true */
 #define BUILD_BUG_ON(condition) ((void)sizeof(struct { int:-!!(condition); }))
 
+/* 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); }))
+
 #ifndef assert_failed
 #define assert_failed(p)                                        \
 do {                                                            \