bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG

[karo-tx-linux.git] / include / linux / compiler.h

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 423bb6bd660ff543fe38f7b3763406327909cfe5..10b8f23fab0f0ad0dfdfcc72ab79b44129772e3d 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -308,11 +308,35 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
 #ifndef __compiletime_error
 # define __compiletime_error(message)
 # define __compiletime_error_fallback(condition) \
-       do { ((void)sizeof(char[1 - 2*!!(condition)])); } while (0)
+       do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
 #else
 # define __compiletime_error_fallback(condition) do { } while (0)
 #endif
 
+#define __compiletime_assert(condition, msg, prefix, suffix)           \
+       do {                                                            \
+               bool __cond = !(condition);                             \
+               extern void prefix ## suffix(void) __compiletime_error(msg); \
+               if (__cond)                                             \
+                       prefix ## suffix();                             \
+               __compiletime_error_fallback(__cond);                   \
+       } while (0)
+
+#define _compiletime_assert(condition, msg, prefix, suffix) \
+       __compiletime_assert(condition, msg, prefix, suffix)
+
+/**
+ * compiletime_assert - break build and emit msg if condition is false
+ * @condition: a compile-time constant condition to check
+ * @msg:       a message to emit if condition is false
+ *
+ * In tradition of POSIX assert, this macro will break the build if the
+ * supplied condition is *false*, emitting the supplied error message if the
+ * compiler has support to do so.
+ */
+#define compiletime_assert(condition, msg) \
+       _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
+
 /*
  * Prevent the compiler from merging or refetching accesses.  The compiler
  * is also forbidden from reordering successive instances of ACCESS_ONCE(),