So not only does the function it does use (`PyCData_nohash`) prevent PyType_Ready from setting _ctypes._SimpleCData.__dict__["__hash__"] to `None`, (contrary to to every other unhashable type in the standard library) but the error message it returns is less detailed.

It seems like a big deal if this were to be changed as it could break backwards compatibility so I won't open PR myself as I'm still not that familiar with the contribution process.