Fix crash in OrderedDict.setdefault when key has unstable hash

Replaced assertion with a runtime check in OrderedDict_setdefault_impl to gracefully handle keys with changing hash values. If such a key is detected, a TypeError is raised instead of aborting the interpreter.
python · dura0ok · Apr 13, 2025 · Apr 13, 2025 · Apr 13, 2025 · 08759edf14a9678bbd2728e550dd7cd3de212e1c
commit 08759edf14a9678bbd2728e550dd7cd3de212e1c
diff --git a/Objects/odictobject.c b/Objects/odictobject.c
@@ -1033,7 +1033,11 @@ OrderedDict_setdefault_impl(PyODictObject *self, PyObject *key,
        if (result == NULL) {
            if (PyErr_Occurred())
                return NULL;
-            assert(_odict_find_node(self, key) == NULL);
+            if (_odict_find_node(self, key) != NULL) {
+                PyErr_SetString(PyExc_RuntimeError,
+                    "OrderedDict key appears to change its hash value over time");
+                return NULL;
+            }
            if (PyODict_SetItem((PyObject *)self, key, default_value) >= 0) {
                result = Py_NewRef(default_value);
            }