bpo-46553: allow bare typing.ClassVar annotations

Lib/test/test_typing.py

@@ -2071,7 +2071,7 @@ def test_fail_with_bare_union(self):
  with self.assertRaises(TypeError):
  Tuple[Optional]
  with self.assertRaises(TypeError):
- ClassVar[ClassVar]
+ ClassVar[ClassVar[int]]
  with self.assertRaises(TypeError):
  List[ClassVar[int]]
 
@@ -2896,12 +2896,16 @@ def test_special_forms_forward(self):
  class C:
  a: Annotated['ClassVar[int]', (3, 5)] = 4
  b: Annotated['Final[int]', "const"] = 4
+ x: 'ClassVar' = 4
+ y: 'Final' = 4
 
  class CF:
  b: List['Final[int]'] = 4
 
  self.assertEqual(get_type_hints(C, globals())['a'], ClassVar[int])
  self.assertEqual(get_type_hints(C, globals())['b'], Final[int])
+ self.assertEqual(get_type_hints(C, globals())['x'], ClassVar)
+ self.assertEqual(get_type_hints(C, globals())['y'], Final)
  with self.assertRaises(TypeError):
  get_type_hints(CF, globals()),
 

Lib/typing.py

@@ -173,7 +173,7 @@ def _type_check(arg, msg, is_argument=True, module=None, *, allow_special_forms=
  if (isinstance(arg, _GenericAlias) and
  arg.__origin__ in invalid_generic_forms):
  raise TypeError(f"{arg} is not valid as type argument")
- if arg in (Any, NoReturn, Final):
+ if arg in (Any, NoReturn, ClassVar, Final):
  return arg
  if isinstance(arg, _SpecialForm) or arg in (Generic, Protocol):
  raise TypeError(f"Plain {arg} is not valid as type argument")

Misc/NEWS.d/next/Library/2022-01-28-08-47-53.bpo-46553.f7Uc96.rst

@@ -0,0 +1 @@
+In :func:`typing.get_type_hints`, support evaluating bare stringified ``ClassVar`` annotations. Patch by Gregory Beauregard.