Add printf format annotations to all '...' functions

To allow the compile to detect incorrect printf formats, any
var-args function should have a format annotation

* common/macros.h: Helper to define ATTR_PRINTF for code
  which can't depend on glib
* common/canvas_base.c, common/lz.h, common/macros.h: Annotate
  some var-args methods

1 files changed, 4 insertions, 3 deletions

diff --git a/common/quic.h b/common/quic.h
index f4ef854..74068f3 100644
--- a/common/quic.h
+++ b/common/quic.h
@@ -20,6 +20,7 @@
 #define __QUIC_H
 
 #include "quic_config.h"
+#include "macros.h"
 
 typedef enum {
     QUIC_IMAGE_TYPE_INVALID,
@@ -37,9 +38,9 @@ typedef void *QuicContext;
 
 typedef struct QuicUsrContext QuicUsrContext;
 struct QuicUsrContext {
-    void (*error)(QuicUsrContext *usr, const char *fmt, ...);
-    void (*warn)(QuicUsrContext *usr, const char *fmt, ...);
-    void (*info)(QuicUsrContext *usr, const char *fmt, ...);
+    ATTR_PRINTF(2, 3) void (*error)(QuicUsrContext *usr, const char *fmt, ...);
+    ATTR_PRINTF(2, 3) void (*warn)(QuicUsrContext *usr, const char *fmt, ...);
+    ATTR_PRINTF(2, 3) void (*info)(QuicUsrContext *usr, const char *fmt, ...);
     void *(*malloc)(QuicUsrContext *usr, int size);
     void (*free)(QuicUsrContext *usr, void *ptr);
     int (*more_space)(QuicUsrContext *usr, uint32_t **io_ptr, int rows_completed);