> According to serge_sans_paille: if ``self->b_ptr`` contains pointer, the ``memcpy`` creates sharing, and this is dangerous: if a ``__del__`` happens to free the original pointer, we end up with a dangling reference in ``new_ptr``. As far as I can tell, this is what happens in the clang bindings code.

We probably need a second parg->obj to keep self alive for as long as copied_self. Or pack it into a tuple.

Having a repro test for this would be ideal, especially if we can make it happen (even crash) on all platforms. The double-free issue would seem to be real, and I don't want it to crash on Windows either.