bpo-42128: Structural Pattern Matching (PEP 634) (GH-22917)

Co-authored-by: Guido van Rossum <guido@python.org>
Co-authored-by: Talin <viridia@gmail.com>
Co-authored-by: Pablo Galindo <pablogsal@gmail.com>
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 415f9a2..e7987a6 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -3052,7 +3052,8 @@ PyTypeObject PyList_Type = {
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_BASETYPE | Py_TPFLAGS_LIST_SUBCLASS, /* tp_flags */
+        Py_TPFLAGS_BASETYPE | Py_TPFLAGS_LIST_SUBCLASS |
+        _Py_TPFLAGS_MATCH_SELF,               /* tp_flags */
     list___init____doc__,                       /* tp_doc */
     (traverseproc)list_traverse,                /* tp_traverse */
     (inquiry)_list_clear,                       /* tp_clear */