btrfs-progs: kerncompat: add build-time assertion support

Macro to verify compile-time conditions, like sie of structures or
types.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/kerncompat.h b/kerncompat.h
index 0cd85dc..ea04ef3 100644 (file)
--- a/kerncompat.h
+++ b/kerncompat.h
@@ -68,6 +68,10 @@
 #define ULONG_MAX       (~0UL)
 #endif
 
+#define __token_glue(a,b,c)    ___token_glue(a,b,c)
+#define ___token_glue(a,b,c)   a ## b ## c
+#define BUILD_ASSERT(x)                extern int __token_glue(compile_time_assert_,__LINE__,__COUNTER__)[1-2*!(x)] __attribute__((unused))
+
 #ifndef BTRFS_DISABLE_BACKTRACE
 #define MAX_BACKTRACE  16
 static inline void print_trace(void)