Tracking issue for DoubleEndedIterator::nth_back

[clarfonthey]

PR: #56802

Currently, none of the standard adapters specialise this except for Rev, which trivially swaps nth and nth_back. These should probably be added before this feature is stabilised, and it's probably a good idea to check if nth should be specialised for any of these adapters too.

Additionally, the standard collection iterators should specialise this where appropriate.

[clarfonthey]

Ping @alexcrichton (or whomever) to add the appropriate labels to this.

[SimonSapin]

#54054 tracks adding more impls of nth_back, but I think this doesn’t need to block stabilization.

@rfcbot fcp merge

[rfcbot]

Team member @SimonSapin has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Amanieu
• @Kimundi
• @SimonSapin
• @alexcrichton
• @dtolnay
• @sfackler
• @withoutboats

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔