[Bug libstdc++/91547] std::string_view find_last_not_of can trigger unsigned integer overflow

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91547

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Vitali from comment #4)
> FWIW clang does implement this. Even if the maintainers disagree on the
> utility in practice, does feature parity for command-line options with Clang
> change the calculus?

See the thread:  https://gcc.gnu.org/legacy-ml/gcc/2016-07/msg00051.html .