On Jan 06, 2016, at 10:13 PM, Serhiy Storchaka wrote:

>What return __reduce_ex__(4) for the NameAssignment instance in 3.5.0?

I'm not sure yet (it takes some time to set up the right environment to test
this), but I do know which TypeError is getting triggered.  In typeobject.c,
it's this stanza in _PyObject_GetState():

        assert(slotnames == Py_None || PyList_Check(slotnames));
        if (required) {
            Py_ssize_t basicsize = PyBaseObject_Type.tp_basicsize;
            if (obj->ob_type->tp_dictoffset)
                basicsize += sizeof(PyObject *);
            if (obj->ob_type->tp_weaklistoffset)
                basicsize += sizeof(PyObject *);
            if (slotnames != Py_None)
                basicsize += sizeof(PyObject *) * Py_SIZE(slotnames);
            if (obj->ob_type->tp_basicsize > basicsize) {
                Py_DECREF(slotnames);
                Py_DECREF(state);
                PyErr_Format(PyExc_TypeError,
                             "can't pickle %.200s objects",
                             Py_TYPE(obj)->tp_name);
                return NULL;
            }
        }

I don't yet know why the basicsize isn't matching up.