fix: Detect deeply recursed global args

Fixes clap-rs#3428

src/build/app/mod.rs

@@ -2704,20 +2704,16 @@ impl<'help> App<'help> {
 
 // Internally used only
 impl<'help> App<'help> {
-    fn get_used_global_args(&self, matcher: &ArgMatcher, global_arg_vec: &mut Vec<Id>) {
+    fn get_used_global_args(&self, matches: &ArgMatches, global_arg_vec: &mut Vec<Id>) {
         global_arg_vec.extend(
             self.args
                 .args()
                 .filter(|a| a.get_global())
                 .map(|ga| ga.id.clone()),
         );
-        if let Some(used_subcommand) = matcher.subcommand.as_ref() {
-            if let Some(used_subcommand) = self
-                .subcommands
-                .iter()
-                .find(|subcommand| subcommand.id == used_subcommand.id)
-            {
-                return used_subcommand.get_used_global_args(matcher, global_arg_vec);
+        if let Some((id, matches)) = matches.subcommand() {
+            if let Some(used_sub) = self.find_subcommand(id) {
+                used_sub.get_used_global_args(matches, global_arg_vec);
             }
         }
     }

tests/builder/global_args.rs

@@ -88,3 +88,23 @@ fn global_arg_available_in_subcommand() {
     assert!(m.is_present("global"));
     assert!(m.subcommand_matches("ping").unwrap().is_present("global"));
 }
+
+#[test]
+fn deeply_nested_discovery() {
+    let app = App::new("a").arg(arg!(--"long-a").global(true)).subcommand(
+        App::new("b").arg(arg!(--"long-b").global(true)).subcommand(
+            App::new("c")
+                .arg(arg!(--"long-c").global(true))
+                .subcommand(App::new("d")),
+        ),
+    );
+
+    let m = app
+        .try_get_matches_from(["a", "b", "c", "d", "--long-a", "--long-b", "--long-c"])
+        .unwrap();
+    assert!(m.is_present("long-a"));
+    let m = m.subcommand_matches("b").unwrap();
+    assert!(m.is_present("long-b"));
+    let m = m.subcommand_matches("c").unwrap();
+    assert!(m.is_present("long-c"));
+}