[PATCH v2 09/10] bug.h: Add BUILD_BUG_ON_MSG & BUILD_BUG_INTERNAL{,2}

danielfsantos
2012-10-05T19:43:57Z

Add BUILD_BUG_ON_MSG which behaves like BUILD_BUG_ON (with optimizations
turned enabled), except that it allows you to specify the error message
you want emitted as the third parameter. Under the hood, this relies on
BUILD_BUG_INTERNAL{,2}, which does the actual work and is pretty-much
identical to BUILD_BUG_ON.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
---
include/linux/bug.h | 26 ++++++++++++++++++++++++++
1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/include/linux/bug.h b/include/linux/bug.h
index 1b43ea2..91bd9d5 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -16,6 +16,7 @@ struct pt_regs;
#define BUILD_BUG_ON_NOT_POWER_OF_2(n)
#define BUILD_BUG_ON_ZERO(e) (0)
#define BUILD_BUG_ON_NULL(e) ((void*)0)
+#define BUILD_BUG_ON_MSG(cond, msg) (0)
#define BUILD_BUG_ON(condition) (0)
#define BUILD_BUG() (0)
#else /* __CHECKER__ */
@@ -38,6 +39,31 @@ struct pt_regs;
*/
#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))

+#define _CONCAT1(a, b) a##b
+#define CONCAT(a, b) _CONCAT1(a, b)
+#define UNIQUIFY(prefix) CONCAT(prefix, __LINE__)
+
+#define BUILD_BUG_INTERNAL2(condition, msg, fn) \
+ do { \
+ extern void fn (void) __compiletime_error(msg); \
+ __compiletime_error_fallback(condition); \
+ if (condition) \
+ fn(); \
+ } while (0)
+
+#define BUILD_BUG_INTERNAL(condition, msg, fn) \
+ BUILD_BUG_INTERNAL2(condition, msg, fn)
+
+/**
+ * BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied
+ * error message.
+ * @condition: the condition which the compiler should know is false.
+ *
+ * See BUILD_BUG_ON for description.
+ */
+#define BUILD_BUG_ON_MSG(cond, msg) \
+ BUILD_BUG_INTERNAL(cond, msg, UNIQUIFY(__build_bug_on_failed_))
+
/**
* BUILD_BUG_ON - break compile if a condition is true.
* @condition: the condition which the compiler should know is false.
--
1.7.3.4