Allow instantiation of type[None] (#19782)

Fixes #19660

---------

Co-authored-by: Shantanu Jain <hauntsaninja@gmail.com>

Author: codenamenam

mypy/checkexpr.py

@@ -2009,6 +2009,17 @@ def analyze_type_type_callee(self, item: ProperType, context: Context) -> Type:
             return self.analyze_type_type_callee(tuple_fallback(item), context)
         if isinstance(item, TypedDictType):
             return self.typeddict_callable_from_context(item)
+        if isinstance(item, NoneType):
+            # NoneType() returns None, so treat it as a callable that returns None
+            return CallableType(
+                arg_types=[],
+                arg_kinds=[],
+                arg_names=[],
+                ret_type=NoneType(),
+                fallback=self.named_type("builtins.function"),
+                name=None,
+                from_type_type=True,
+            )
 
         self.msg.unsupported_type_type(item, context)
         return AnyType(TypeOfAny.from_error)

test-data/unit/check-classes.test

@@ -3957,6 +3957,23 @@ def f(a: Type[Tuple[int, int]]):
     a()  # E: Cannot instantiate type "type[tuple[int, int]]"
 [builtins fixtures/tuple.pyi]
 
+[case testTypeUsingTypeCNoneType]
+from typing_extensions import assert_type
+
+NoneType = type(None)
+assert_type(type(None)(), None)
+assert_type(NoneType(), None)
+
+def f(n: type[None]):
+    assert_type(n(), None)
+    n(1)  # E: Too many arguments
+def g(n: type[NoneType]):
+    assert_type(n(), None)
+
+f(NoneType)
+g(NoneType)
+[builtins fixtures/tuple.pyi]
+
 [case testTypeUsingTypeCNamedTuple]
 from typing import Type, NamedTuple
 N = NamedTuple('N', [('x', int), ('y', int)])