build_bug.h: add wrapper for _Static_assert

[linux-2.6-microblaze.git] / include / linux / build_bug.h

diff --git a/include/linux/build_bug.h b/include/linux/build_bug.h
index faeec74..0fe5426 100644 (file)
--- a/include/linux/build_bug.h
+++ b/include/linux/build_bug.h
@@ -58,4 +58,23 @@
  */
 #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
 
+/**
+ * static_assert - check integer constant expression at build time
+ *
+ * static_assert() is a wrapper for the C11 _Static_assert, with a
+ * little macro magic to make the message optional (defaulting to the
+ * stringification of the tested expression).
+ *
+ * Contrary to BUILD_BUG_ON(), static_assert() can be used at global
+ * scope, but requires the expression to be an integer constant
+ * expression (i.e., it is not enough that __builtin_constant_p() is
+ * true for expr).
+ *
+ * Also note that BUILD_BUG_ON() fails the build if the condition is
+ * true, while static_assert() fails the build if the expression is
+ * false.
+ */
+#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
+#define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
+
 #endif /* _LINUX_BUILD_BUG_H */