[3.9] bpo-42332: Add weakref slot to types.GenericAlias (GH-23250) (GH-23309)

(cherry picked from commit 384b7a4bd988986bca227c7e85c32d766da74708)

1 files changed, 6 insertions, 0 deletions

diff --git a/Objects/genericaliasobject.c b/Objects/genericaliasobject.c
index 3e850b5..4b6c8c6 100644
--- a/Objects/genericaliasobject.c
+++ b/Objects/genericaliasobject.c
@@ -9,6 +9,7 @@ typedef struct {
     PyObject *origin;
     PyObject *args;
     PyObject *parameters;
+    PyObject* weakreflist;
 } gaobject;
 
 static void
@@ -17,6 +18,9 @@ ga_dealloc(PyObject *self)
     gaobject *alias = (gaobject *)self;
 
     _PyObject_GC_UNTRACK(self);
+    if (alias->weakreflist != NULL) {
+        PyObject_ClearWeakRefs((PyObject *)alias);
+    }
     Py_XDECREF(alias->origin);
     Py_XDECREF(alias->args);
     Py_XDECREF(alias->parameters);
@@ -593,6 +597,7 @@ PyTypeObject Py_GenericAliasType = {
     .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .tp_traverse = ga_traverse,
     .tp_richcompare = ga_richcompare,
+    .tp_weaklistoffset = offsetof(gaobject, weakreflist),
     .tp_methods = ga_methods,
     .tp_members = ga_members,
     .tp_alloc = PyType_GenericAlloc,
@@ -624,6 +629,7 @@ Py_GenericAlias(PyObject *origin, PyObject *args)
     alias->origin = origin;
     alias->args = args;
     alias->parameters = NULL;
+    alias->weakreflist = NULL;
     _PyObject_GC_TRACK(alias);
     return (PyObject *)alias;
 }