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4449. define_aggregate members must be public

Section: 21.4.16 [meta.reflection.define.aggregate] Status: Immediate Submitter: Daniel Katz Opened: 2025-11-05 Last modified: 2025-11-05

Priority: Not Prioritized

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Discussion:

The access of members of classes defined by injected declarations produced by evaluations of std::meta::define_aggregate is unspecified.

[Kona 2025-11-05; approved by LWG. Status changed: New → Immediate.]

Proposed resolution:

This wording is relative to N5014.

1. Modify 21.4.16 [meta.reflection.define.aggregate] as indicated:

   template<reflection_range R = initializer_list<info>>
     consteval info define_aggregate(info class_type, R&& mdescrs);
   

   -7- Let C be the class represented by class_type and rK be the K^th reflection value in mdescrs. […]

   -8- Constant When: […]

   -9- Effects: Produces an injected declaration D (7.7 [expr.const]) that defines C and has properties as follows:

   • (9.1) — […]
   • (9.2) — […]
   • (9.3) — […]
   • (9.4) — […]
   • (9.5) — For each rK, there is a corresponding entity MK with public access belonging to the class scope of D with the following properties: […]
   • (9.6) — […]