[Qemu-devel] [PATCH 2/3] nbd: Avoid bitrot in TRACE() usage

[Eric Blake <eblake@redhat.com>]

The compiler is smart enough to optimize out 'if (0)', but won't
type-check our printfs if they are hidden behind #if.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 nbd/nbd-internal.h | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index 127c48d..f4dce06 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -33,18 +33,21 @@
 #define DEBUG_NBD

 #ifdef DEBUG_NBD
-#define TRACE(msg, ...) do { \
-    LOG(msg, ## __VA_ARGS__); \
-} while(0)
+#define DEBUG_NBD_PRINT 1
 #else
-#define TRACE(msg, ...) \
-    do { } while (0)
+#define DEBUG_NBD_PRINT 0
 #endif

+#define TRACE(msg, ...) do { \
+    if (DEBUG_NBD_PRINT) { \
+        LOG(msg, ## __VA_ARGS__); \
+    } \
+} while (0)
+
 #define LOG(msg, ...) do { \
     fprintf(stderr, "%s:%s():L%d: " msg "\n", \
             __FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
-} while(0)
+} while (0)

 /* This is all part of the "official" NBD API.
  *
-- 
2.5.5