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### 3751. Missing feature macro for `flat_set`

Section: 17.3.2 [version.syn] Status: WP Submitter: Barry Revzin Opened: 2022-08-04 Last modified: 2022-11-17

Priority: Not Prioritized

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Discussion:

As pointed out by Casey Carter, while there is a feature macro for `flat_map` in P0429, there is no corresponding macro for flat_set in P1222. We should add one.

[2022-08-23; Reflector poll]

Set status to Tentatively Ready after 10 votes in favour during reflector poll.

[2022-11-12 Approved at November 2022 meeting in Kona. Status changed: Voting → WP.]

Proposed resolution:

1. Modify 17.3.2 [version.syn] as indicated:

   >     #define __cpp_lib_flat_map  202207L // also in <flat_map>
   >     #define __cpp_lib_flat_set  202207L // also in <flat_set>