You could always know if a function was compile-time or not based on the usages. Eg, static_assert the output or put it in a constexpr value, and it's guarantee

You could always know if a function was compile-time or not based on the usages. Eg, static_assert the output or put it in a constexpr value, and it's guaranteed to be compile-time evaluated or it didn't compile. consteval is helpful in iterations during development to catch that, and I like it as such, but it's definitely not a constexpr replacement nor what constexpr should have been. It's a very small subset of constexpr usages.