Make types.MappingProxyType generic (python#13)

Author: emmatyping

Lib/test/test_genericalias.py

@@ -8,7 +8,7 @@
 from collections.abc import *
 from contextlib import AbstractContextManager, AbstractAsyncContextManager
 from re import Pattern, Match
-from types import GenericAlias
+from types import GenericAlias, MappingProxyType
 
 from typing import TypeVar
 T = TypeVar('T')
@@ -33,6 +33,7 @@ def test_subscriptable(self):
                   Mapping, MutableMapping, MappingView,
                   KeysView, ItemsView, ValuesView,
                   Sequence, MutableSequence,
+                  MappingProxyType,
                   ):
             tname = t.__name__
             with self.subTest(f"Testing {tname}"):

Objects/descrobject.c

@@ -1066,6 +1066,8 @@ static PyMethodDef mappingproxy_methods[] = {
      PyDoc_STR("D.items() -> list of D's (key, value) pairs, as 2-tuples")},
     {"copy",      (PyCFunction)mappingproxy_copy,       METH_NOARGS,
      PyDoc_STR("D.copy() -> a shallow copy of D")},
+    {"__class_getitem__", (PyCFunction)Py_GenericAlias, METH_O|METH_CLASS,
+     PyDoc_STR("See PEP 585")},
     {0}
 };