[Bug libstdc++/122224] std::prev when called with non-bidirectional iterators

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122224

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> So we accept calling std::prev(it, n) on input iterators, but assert if n >=
> 0.

Which is consistent with the standard's precondition for std::advance:

Preconditions: n is negative only for bidirectional iterators.