[jcelerier]

> C++20 supports enums as non-type template parameters, so I think it'd be possible to do it with enums there. Something like:

Even c++98 supported that already : https://gcc.godbolt.org/z/7xma_u

[logicchains]

Good point, I suppose of course it does, since enums are just ints. But C++20 adds support for enum classes (and also variants when they can be defined as value types with a defaulted operator<==>).

[jcelerier]

> But C++20 adds support for enum classes

It seems to work fine with `enum class` under C++11 ? your code works almost inchanged in g++ 4.7. I don't see anything here : https://en.cppreference.com/w/cpp/language/template_paramete... that adds specific support for that in C++20

[logicchains]

Wow it does too, not sure where I got it into my head that it didn't then.