[Bug libstdc++/106676] [C++20] Automatic iterator_category detection misbehaves when `::reference` is an rvalue reference, refuses to accept a forward iterator

[avi at scylladb dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106676

--- Comment #9 from Avi Kivity <avi at scylladb dot com> ---
iterator_concept echos its input. Love C++.