[PATCH 1/3] checkpatch: dont warn about unused macro arg on empty body

[Jim Cromie <jim.cromie@gmail.com>]

we currently get:
  WARNING: Argument 'name' is not used in function-like macro
on:
  #define DRM_CLASSMAP_USE(name)  /* nothing here */

Following this advice is wrong here, and shouldn't be fixed by
ignoring args altogether; the macro should properly fail if invoked
with 0 or 2+ args.

cc: Andy Whitcroft <apw@canonical.com>
cc: Joe Perches <joe@perches.com>
cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: Joe Perches <joe@perches.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
 scripts/checkpatch.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 7b28ad331742..0c4f578ea6e7 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6037,7 +6037,7 @@ sub process {
 				}
 
 # check if this is an unused argument
-				if ($define_stmt !~ /\b$arg\b/) {
+				if ($define_stmt !~ /\b$arg\b/ && $define_stmt) {
 					WARN("MACRO_ARG_UNUSED",
 					     "Argument '$arg' is not used in function-like macro\n" . "$herectx");
 				}
-- 
2.49.0