On Mon, Jan 19, 2026 at 09:42:05AM -0500, Daniel Katz wrote: > Thanks for raising this issue, Jakub. > > I'm going to circle back with my coauthors regarding rationale for > extending consteval-only-ness to pointers and references. > > If such types weren't consteval-only, do you think that would be sufficient > to solve the issue? Any concerns that come to mind with that approach > (e.g., ways that it would allow meta::info to leak to anytime)?
I've filed https://github.com/cplusplus/CWG/issues/836 so it can be discussed further there (though perhaps I should have included there more details). If e.g. pointers to consteval-only aren't consteval-only (or perhaps they are treated that way from within class non-static data members but not otherwise), then the question is how to arrange after struct A; A *p; struct A { std::meta::info a; }; not emitting runtime code which dereferences *p, it is fine to emit such a pointer into the compiled code, it has well defined size etc. But one better wouldn't dereference such pointer (which it can't be dereferenced before the class is complete, and can't be dereferenced in constant evaluated code because the var is not constexpr). >From the implementation POV, I think it would be easier if we could decide if a class is consteval-only or not at the class definition time rather than having to defer all the consteval-only related decisions until end of TU, whether it is just non-static data members in there with consteval-only class types / std::meta::info or pointers/references/array/function types to those too (for references I guess the referenced type needs to be complete at least in the NSDMs, but in function types one can have references to incomplete types: struct S; struct T { int (*p) (S &); }; ). Though it would be really complicated if we had say consteval-only vs. non-consteval-only pointers to the same class and had to treat them differently (non-consteval-only e.g. ones parsed when the pointed type was still incomplete and consteval-only when it was complete and determined to be consteval-only). Jakub
