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/unicodeobject.c b/Objects/unicodeobject.c
index 5e1b6b0..0b08b0e 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -15657,7 +15657,8 @@ PyTypeObject PyUnicode_Type = {
     0,                            /* tp_setattro */
     0,                            /* tp_as_buffer */
     Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
-    Py_TPFLAGS_UNICODE_SUBCLASS,   /* tp_flags */
+        Py_TPFLAGS_UNICODE_SUBCLASS |
+        _Py_TPFLAGS_MATCH_SELF, /* tp_flags */
     unicode_doc,                  /* tp_doc */
     0,                            /* tp_traverse */
     0,                            /* tp_clear */