gh-146056: Fix TreeBuilder stack in xml.etree by vstinner · Pull Request #146062 · python/cpython

    PyObject *last = self->last;
    PyObject *last_for_tail = self->last_for_tail;
    PyObject *this = self->this;
    self->index--;
    self->this = Py_NewRef(PyList_GET_ITEM(self->stack, self->index));
    self->last = Py_NewRef(this);
    self->last_for_tail = Py_NewRef(this);
    Py_DECREF(last);
    Py_XDECREF(last_for_tail);

    if (treebuilder_append_event(self, self->end_event_obj, this) < 0) {
        Py_DECREF(this);
        return NULL;
    }

    return this;