readline: Add missing GCC_FMT_ATTR

This fixes a compiler warning with -Werror=missing-format-attribute
and allows improved compiler checks for variable argument lists.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

1 files changed, 2 insertions, 1 deletions

diff --git a/monitor.c b/monitor.c
index 80456fbe5b..5ba541dc6f 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4888,7 +4888,8 @@ static void sortcmdlist(void)
 /* These functions just adapt the readline interface in a typesafe way.  We
  * could cast function pointers but that discards compiler checks.
  */
-static void monitor_readline_printf(void *opaque, const char *fmt, ...)
+static void GCC_FMT_ATTR(2, 3) monitor_readline_printf(void *opaque,
+                                                       const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);