Better handling for generic aliases

Author: ilevkivskyi

mypy/types.py

@@ -3988,7 +3988,10 @@ def visit_type_alias_type(self, t: TypeAliasType, /) -> str:
         if t.alias is None:
             return "<alias (unfixed)>"
         if self.reveal_simple_types:
-            return t.alias.name
+            type_str = t.alias.name
+            if t.args:
+                type_str += f"[{self.list_str(t.args)}]"
+            return type_str
         if not t.is_recursive:
             return get_proper_type(t).accept(self)
         if self.dotted_aliases is None:

test-data/unit/check-flags.test

@@ -2759,4 +2759,8 @@ class User(TypedDict):
 
 def bar(x: int, **kwargs: Unpack[User]) -> None: ...
 reveal_type(bar)  # N: Revealed type is "def (x: int, **kwargs: **TypedDict(User, {'age': int, 'name': str}))"
+
+Alias = tuple[T, S]
+x: Alias[int, str]
+reveal_type(x)  # N: Revealed type is "Alias[int, str]"
 [builtins fixtures/tuple.pyi]