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### 3713. Sorted with respect to comparator (only)

Section: 27.8.1 [alg.sorting.general] Status: WP Submitter: Casey Carter Opened: 2022-06-10 Last modified: 2022-07-25

Priority: Not Prioritized

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Discussion:

P0896R4 changed the term of art "sorted with respect to comparator" defined in 27.8.1 [alg.sorting.general] paragraph 5 to "sorted with respect to comparator and projection." That proposal updated the algorithm specifications consistently. However, there were uses of the old term outside of 27 [algorithms] that are now without meaning. We should bring back the term "sorted with respect to comparator" to fix that lack.

[2022-06-21; Reflector poll]

Set status to Tentatively Ready after eight votes in favour during reflector poll.

[2022-07-15; LWG telecon: move to Ready]

[2022-07-25 Approved at July 2022 virtual plenary. Status changed: Ready → WP.]

Proposed resolution:

This wording is relative to N4910.

1. Modify 27.8.1 [alg.sorting.general] as indicated:

   > -5- A sequence is sorted with respect to a `comp` and `proj` for a comparator and projection `comp` and `proj` if for every iterator `i` pointing to the sequence and every non-negative integer `n` such that `i + n` is a valid iterator pointing to an element of the sequence,

   > >     bool(invoke(comp, invoke(proj, *(i + n)), invoke(proj, *i)))

   > is `false`.

   > -?- A sequence is sorted with respect to a comparator `comp` for a comparator `comp` if it is sorted with respect to `comp` and `identity{}` (the identity projection).