Re: [boost] Fixed String review

Krystian Stasiowski wrote:

Perhaps we provide two separate functions like was mentioned previously, where one returns a fixed_string and the other returns a string_view.

I think that this is almost certainly the right thing to do, both for fixed_string and for std::string. Call the string_view returning function `s.subview()` or just `s.view()`, leave `s.substr()` to return by value.