https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114149
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
We would need something like this to ensure we don't use memcmp for insane
iterators that use exceptions for flow control to exit algorithms early:
// N.B. this is not the same as nothrow-forward-iterator, which doesn't
// require noexcept operations, it just says it's undefined if they throw.
// Here we require them to be actually noexcept.
template<typename _Iter>
concept __nothrow_contiguous_iterator
= contiguous_iterator<_Iter> && requires (_Iter __i) {
// If these operations can throw then the iterator could cause
// the algorithm to exit early via an exception, in which case
// we can't use memcmp, memcpy, etc.
{ *__i } noexcept;
{ ++__i } noexcept;
};
