Add test of matches macro for trailing commas

src/test/ui/macros/macro-comma-support-rpass.rs

@@ -192,6 +192,12 @@ fn line() {
     let _ = line!();
 }
 
+#[test]
+fn matches() {
+    let _ = matches!(1, x if x > 0);
+    let _ = matches!(1, x if x > 0,);
+}
+
 #[test]
 fn module_path() {
     let _ = module_path!();