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4416. <meta> should include <compare>

Section: 21.4.1 [meta.syn] Status: Tentatively Ready Submitter: Jiang An Opened: 2025-10-15 Last modified: 2025-10-20

Priority: Not Prioritized

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Discussion:

Some inclusions from <meta> were removed between P2996R7 and P2996R8. However, given std::meta::member_offsets has operator<=>, perhaps we should still include <compare> in <meta>. This is also noticed in P3429R1.

[2025-10-20; Reflector poll.]

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

Proposed resolution:

This wording is relative to N5014.

1. Modify 21.4.1 [meta.syn], header <meta> synopsis, as indicated:

   #include <compare> // see 17.12.1 [compare.syn]
   #include <initializer_list> // see 17.11.2 [initializer.list.syn]
   
   namespace std {
     […]
   }