> xrange() constructor is implemented in C and looks to use C long for
> parameters. This issue is specific to 64-bit Windows with 32-bit C long, so
> xrange() doesn't seem to work here.

What about xrange(-1, 2**31-1)? In any case the fact that xrange works not 
with Py_ssize_t, but with long, looks as a bug. I'll open a separate issue for 
this.

> > Or weakref?
> 
> What do you mean? Which object? weakref.ref() has no length.

I see that the sq_length slot in the weakproxy type is set to proxy_length.