Issue #15142: Fix reference leak when deallocating instances of types created…

Issue #15142: Fix reference leak when deallocating instances of types created using PyType_FromSpec().

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.3.0 Beta 1?
 Core and Builtins
 -----------------
 
+- Issue #15142: Fix reference leak when deallocating instances of types
+  created using PyType_FromSpec().
+
 - Issue #15042: Add PyState_AddModule and PyState_RemoveModule. Add version
   guard for Py_LIMITED_API additions. Patch by Robin Schreiber.
 

Objects/typeobject.c

@@ -2417,6 +2417,12 @@ PyType_FromSpec(PyType_Spec *spec)
     if (res->ht_type.tp_dictoffset) {
         res->ht_cached_keys = _PyDict_NewKeysForClass();
     }
+    if (res->ht_type.tp_dealloc == NULL) {
+        /* It's a heap type, so needs the heap types' dealloc.
+           subtype_dealloc will call the base type's tp_dealloc, if
+           necessary. */
+        res->ht_type.tp_dealloc = subtype_dealloc;
+    }
 
     if (PyType_Ready(&res->ht_type) < 0)
         goto fail;