fix: Resolve conflicting name inference if from aliases

Signed-off-by: Alex Saveau <[email protected]>

clap_builder/src/parser/parser.rs

@@ -544,19 +544,24 @@ impl<'cmd> Parser<'cmd> {
             if self.cmd.is_infer_subcommands_set() {
                 // For subcommand `test`, we accepts it's prefix: `t`, `te`,
                 // `tes` and `test`.
-                let v = self
-                    .cmd
-                    .all_subcommand_names()
-                    .filter(|s| s.starts_with(arg))
-                    .collect::<Vec<_>>();
+                let mut iter = self.cmd.get_subcommands().filter_map(|s| {
+                    if s.get_name().starts_with(arg) {
+                        return Some(s.get_name());
+                    }
 
-                if v.len() == 1 {
-                    return Some(v[0]);
-                }
+                    // Use find here instead of chaining the iterator because we want to accept
+                    // conflicts in aliases.
+                    s.get_all_aliases().find(|s| s.starts_with(arg))
+                });
 
-                // If there is any ambiguity, fallback to non-infer subcommand
-                // search.
+                if let name @ Some(_) = iter.next() {
+                    if iter.next().is_none() {
+                        return name;
+                    }
+                }
             }
+            // Don't use an else here because we want inference to support exact matching even if
+            // there are conflicts.
             if let Some(sc) = self.cmd.find_subcommand(arg) {
                 return Some(sc.get_name());
             }

tests/builder/app_settings.rs

@@ -258,8 +258,9 @@ fn infer_subcommands_pass_conflicting_aliases() {
     let m = Command::new("prog")
         .infer_subcommands(true)
         .subcommand(Command::new("test").aliases(["testa", "t", "testb"]))
-        .try_get_matches_from(vec!["prog", "te"]);
-    assert!(m.is_err(), "{:#?}", m.unwrap());
+        .try_get_matches_from(vec!["prog", "te"])
+        .unwrap();
+    assert_eq!(m.subcommand_name(), Some("test"));
 }
 
 #[test]