P4101R1 — Consteval-only Values for C++26
Barry Revzin, Peter Dimov, Daveed Vandevoorde, Dan Katz
EWGCWG
Revisions R1Jul 2026R0Apr 2026
The Reflection design from [[P2996R13]](https://wg21.link/p2996r13) was based on a model of having consteval-only types to prevent reflections from leaking to runtime. But we’ve run into issues and limitations with that approach, so we propose that, for C++26, we change instead to a consteval-only value model. This solves the same problems, but has additional benefits.