rculfhash: use do {} while (0) for dbg_printf()

found by clang(make CC=clang).

avoid empty statement.
-------------------------
if (condition)
        dbg_printf()  /* forget ";", but compiler say nothing if dbg_printf() is empty */
statement;
-------------------------

also add printf format check.
(we can use gcc extention "__printf(1, 2)" to declare a dummy inline function
to do the check, but I use "printf()" directly here)

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/rculfhash-internal.h b/rculfhash-internal.h
index 284125af29887ca474206391ae69e0fe5d7eec2f..d7cec95a10e286f4693c91925e61441146196ebe 100644 (file)
--- a/rculfhash-internal.h
+++ b/rculfhash-internal.h
@@ -25,11 +25,17 @@
  */
 
 #include <urcu/rculfhash.h>
+#include <stdio.h>
 
 #ifdef DEBUG
 #define dbg_printf(fmt, args...)     printf("[debug rculfhash] " fmt, ## args)
 #else
-#define dbg_printf(fmt, args...)
+#define dbg_printf(fmt, args...)                               \
+do {                                                           \
+       /* do nothing but check printf format */                \
+       if (0)                                                  \
+               printf("[debug rculfhash] " fmt, ## args);      \
+} while (0)
 #endif
 
 #if (CAA_BITS_PER_LONG == 32)