Make ContextVar generic

Author: emmatyping

Lib/test/test_genericalias.py

@@ -9,7 +9,7 @@
 from concurrent.futures import Future
 from concurrent.futures.thread import _WorkItem
 from contextlib import AbstractContextManager, AbstractAsyncContextManager
-from contextvars import Token
+from contextvars import ContextVar, Token
 from dataclasses import Field
 from mailbox import Mailbox, _PartialFile
 from ctypes import Array, LibraryLoader
@@ -57,7 +57,7 @@ def test_subscriptable(self):
                   Container, Collection,
                   Callable,
                   Mailbox, _PartialFile,
-                  Token,
+                  ContextVar, Token,
                   Field,
                   Set, MutableSet,
                   Mapping, MutableMapping, MappingView,

Python/context.c

@@ -1023,13 +1023,6 @@ _contextvars_ContextVar_reset(PyContextVar *self, PyObject *token)
 }
 
 
-static PyObject *
-contextvar_cls_getitem(PyObject *self, PyObject *arg)
-{
-    Py_INCREF(self);
-    return self;
-}
-
 static PyMemberDef PyContextVar_members[] = {
     {"name", T_OBJECT, offsetof(PyContextVar, var_name), READONLY},
     {NULL}
@@ -1039,8 +1032,8 @@ static PyMethodDef PyContextVar_methods[] = {
     _CONTEXTVARS_CONTEXTVAR_GET_METHODDEF
     _CONTEXTVARS_CONTEXTVAR_SET_METHODDEF
     _CONTEXTVARS_CONTEXTVAR_RESET_METHODDEF
-    {"__class_getitem__", contextvar_cls_getitem,
-        METH_O | METH_CLASS, NULL},
+    {"__class_getitem__", (PyCFunction)Py_GenericAlias,
+    METH_O|METH_CLASS,       PyDoc_STR("See PEP 585")},
     {NULL, NULL}
 };