Performance aside, using variant has an added benefit of making illegal states unrepresentable. Optionals + an enum still allows users to either nullopt all the members, or have more than one member that is not nullopt.

> I assumed it would be clear to anyone who knows

It's just not possible to assume that at all on the internet. Every year I have students who learn from blog posts like this for instance.

As someone who does quite a bit of C++ recently: for most uses readability is king.

If you did want squeeze out the extra performance you could also do something where you store `std::variant<>` inside a struct and provide an API like this:

    if (auto int_value = value.i()) {
      // *int_value == your int
    }

and expose a `std::variant<> &variant();` for use cases where you want the more complex/faster stuff.

Using variant as the storage type while providing a nice public accessor API makes sense given the huge difference in semantics between a struct containing optional fields and a variant.