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4292. Unordered container local iterators should be constexpr iterators

Section: 23.5.3.1 [unord.map.overview], 23.5.4.1 [unord.multimap.overview], 23.5.6.1 [unord.set.overview], 23.5.7.1 [unord.multiset.overview] Status: WP Submitter: Jonathan Wakely Opened: 2025-07-10 Last modified: 2025-11-11

Priority: Not Prioritized

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Discussion:

The intent of P3372R3 was for all container iterators to be constexpr iterators, but during application of the paper to the working draft it was observed that unordered containers don't say it for their local iterators.

[2025-08-29; Reflector poll]

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

[Kona 2025-11-08; Status changed: Voting → WP.]

Proposed resolution:

This wording is relative to N5008.

1. Modify 23.5.3.1 [unord.map.overview] as indicated:

   -4- The types iterator, and const_iterator, local_iterator, and const_local_iterator meet the constexpr iterator requirements (24.3.1 [iterator.requirements.general]).

2. Modify 23.5.4.1 [unord.multimap.overview] as indicated:

   -4- The types iterator, and const_iterator, local_iterator, and const_local_iterator meet the constexpr iterator requirements (24.3.1 [iterator.requirements.general]).

3. Modify 23.5.6.1 [unord.set.overview] as indicated:

   -4- The types iterator, and const_iterator, local_iterator, and const_local_iterator meet the constexpr iterator requirements (24.3.1 [iterator.requirements.general]).

4. Modify 23.5.7.1 [unord.multiset.overview] as indicated:

   -4- The types iterator, and const_iterator, local_iterator, and const_local_iterator meet the constexpr iterator requirements (24.3.1 [iterator.requirements.general]).