[Bug libstdc++/107871] _Iter_sink:: _M_overflow missing some difference type casting

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107871

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Maybe you could legally do:

using difference_type = iterator_t<iota_view<__int128, __int128>>;

but maybe just don't do that. If things break when you do dumb things, don't do
those things.