diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py index 21bc7c81f2a30e..f429e883b59538 100644 --- a/Lib/test/test_typing.py +++ b/Lib/test/test_typing.py @@ -10,7 +10,7 @@ from typing import TypeVar, AnyStr from typing import T, KT, VT # Not in __all__. from typing import Union, Optional, Literal -from typing import Tuple, List, MutableMapping +from typing import Tuple, List, Dict, MutableMapping from typing import Callable from typing import Generic, ClassVar, Final, final, Protocol from typing import cast, runtime_checkable @@ -3173,6 +3173,17 @@ def test_frozenset(self): def test_dict(self): self.assertIsSubclass(dict, typing.Dict) + def test_dict_subscribe(self): + K = TypeVar('K') + V = TypeVar('V') + self.assertEqual(Dict[K, V][str, int], Dict[str, int]) + self.assertEqual(Dict[K, int][str], Dict[str, int]) + self.assertEqual(Dict[str, V][int], Dict[str, int]) + self.assertEqual(Dict[K, List[V]][str, int], Dict[str, List[int]]) + self.assertEqual(Dict[K, List[int]][str], Dict[str, List[int]]) + self.assertEqual(Dict[K, list[V]][str, int], Dict[str, list[int]]) + self.assertEqual(Dict[K, list[int]][str], Dict[str, list[int]]) + def test_no_list_instantiation(self): with self.assertRaises(TypeError): typing.List() diff --git a/Lib/typing.py b/Lib/typing.py index e31fc99e02245e..b5ba38e07c835b 100644 --- a/Lib/typing.py +++ b/Lib/typing.py @@ -702,8 +702,10 @@ def __getitem__(self, params): if isinstance(arg, TypeVar): arg = subst[arg] elif isinstance(arg, (_GenericAlias, GenericAlias)): - subargs = tuple(subst[x] for x in arg.__parameters__) - arg = arg[subargs] + subparams = arg.__parameters__ + if subparams: + subargs = tuple(subst[x] for x in subparams) + arg = arg[subargs] new_args.append(arg) return self.copy_with(tuple(new_args))