bpo-46539: Pass status of special typeforms to forward references

Lib/test/test_typing.py

@@ -2870,6 +2870,13 @@ def foo(a: 'Callable[..., T]'):
         self.assertEqual(get_type_hints(foo, globals(), locals()),
                          {'a': Callable[..., T]})
 
+    def test_special_forms_forward(self):
+
+        class C:
+            a: Annotated['ClassVar[int]', (3, 5)] = 4
+
+        self.assertEqual(get_type_hints(C, globals())['a'], ClassVar[int])
+
     def test_syntax_error(self):
 
         with self.assertRaises(SyntaxError):

Lib/typing.py

@@ -142,12 +142,12 @@ def _idfunc(_, x):
 # legitimate imports of those modules.
 
 
-def _type_convert(arg, module=None):
+def _type_convert(arg, module=None, *, allow_special_forms=False):
     """For converting None to type(None), and strings to ForwardRef."""
     if arg is None:
         return type(None)
     if isinstance(arg, str):
-        return ForwardRef(arg, module=module)
+        return ForwardRef(arg, module=module, is_class=allow_special_forms)
     return arg
 
 
@@ -169,7 +169,7 @@ def _type_check(arg, msg, is_argument=True, module=None, *, allow_special_forms=
         if is_argument:
             invalid_generic_forms += (Final,)
 
-    arg = _type_convert(arg, module=module)
+    arg = _type_convert(arg, module=module, allow_special_forms=allow_special_forms)
     if (isinstance(arg, _GenericAlias) and
             arg.__origin__ in invalid_generic_forms):
         raise TypeError(f"{arg} is not valid as type argument")
@@ -661,7 +661,7 @@ class ForwardRef(_Final, _root=True):
 
     __slots__ = ('__forward_arg__', '__forward_code__',
                  '__forward_evaluated__', '__forward_value__',
-                 '__forward_is_argument__', '__forward_is_class__',
+                 '__forward_is_argument__', '__forward_allow_special_forms__',
                  '__forward_module__')
 
     def __init__(self, arg, is_argument=True, module=None, *, is_class=False):
@@ -676,7 +676,7 @@ def __init__(self, arg, is_argument=True, module=None, *, is_class=False):
         self.__forward_evaluated__ = False
         self.__forward_value__ = None
         self.__forward_is_argument__ = is_argument
-        self.__forward_is_class__ = is_class
+        self.__forward_allow_special_forms__ = is_class
         self.__forward_module__ = module
 
     def _evaluate(self, globalns, localns, recursive_guard):
@@ -697,7 +697,7 @@ def _evaluate(self, globalns, localns, recursive_guard):
                 eval(self.__forward_code__, globalns, localns),
                 "Forward references must evaluate to types.",
                 is_argument=self.__forward_is_argument__,
-                allow_special_forms=self.__forward_is_class__,
+                allow_special_forms=self.__forward_allow_special_forms__,
             )
             self.__forward_value__ = _eval_type(
                 type_, globalns, localns, recursive_guard | {self.__forward_arg__}

Misc/NEWS.d/next/Library/2022-01-26-20-36-30.bpo-46539.23iW1d.rst

@@ -0,0 +1 @@
+typing: Pass on status of special forms to forward references. Patch by Gregory Beauregard.