Re: [PATCH] c++/reflection: Support members_of and imported namespace-scope names [PR124200]

[Thomas Berger]

Am Dienstag, 3. März 2026, 16:59:12 Mitteleuropäische Normalzeit schrieb Marek 
Polacek:
> Interesting, thanks.  Dan pointed me to
> https://cplusplus.github.io/LWG/issue4496
> so we should be saying "reachable" rather than "precedes" which is about
> name lookup.

But, as far as i can tell, there is no direct effect on members-of-precedes.
I would argue, that using reachable here would break module boundaries:

  export module A;
  
  namespace NS {
    struct impl_with_side_effects {
       // ...
    }

    export class S {
      protected:
       const std::unique_ptr<impl_with_side_effects> impl;
      // ....
    }

  // main.c
  import A;
  import std;

  consteval void reflect_ns() {
     for (auto member : members_of(^^NS)) {
        // [[: member ]] into existence
     }
  }

Would this be legal? Are there any limitations on slice operations?

Thomas

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