[sheepdog] [PATCH 2/3] util: add BUILD_BUG_ON() for detecting errors at compile time

[Hitoshi Mitake]

This patch adds BUILD_BUG_ON() to include/util.h. The macro can be
used for detecting errors which should cause build
error. e.g. checking struct sizes, etc.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
---
 include/util.h |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/util.h b/include/util.h
index 1bdaf36..68eface 100644
--- a/include/util.h
+++ b/include/util.h
@@ -176,4 +176,8 @@ static inline bool is_stdout_console(void)
 extern mode_t sd_def_fmode;
 extern mode_t sd_def_dmode;
 
+
+/* Force a compilation error if the condition is true */
+#define BUILD_BUG_ON(condition) ((void)sizeof(struct { int: -!!(condition); }))
+
 #endif
-- 
1.7.10.rc0.41.gfa678