P2259R1 Repairing Input Range Adaptors And counted_iterator

[StephanTLavavej]

P2259R1 Repairing Input Range Adaptors And counted_iterator

[cpplearner]

This paper resolves LWG-3283, LWG-3289, and LWG-3408. It should probably be treated as a DR and applied to C++20.

[StephanTLavavej]

@CaseyCarter confirmed on Discord:

Oh, there's no question: we should treat it as a DR since the adaptors don't work otherwise. We've already implemented something to get them working (lots of // TRANSITION, LWG-3289 stuff), which IIRC is quite close to the "things that aren't C++17 iterators have no iterator_category" design in the proposal.