Steve Downey:
> That's what the standard refers to now as the internal encoding.
>
> http://eel.is/c++draft/lex#phases-1.1.sentence-4

> Now, this doesn't quite require that the internal encoding be Unicode. If
> I'm reading it correctly, it could be lossy. However, given the other
> requirements around u literals, it's somewhat unlikely. It might be worth
> exploring making it an explicit requirement that the internal encoding be
> some unspecified unicode transform, so even if it's utf-ebcdic, that's ok.

Yes, I think we should mandate Unicode.

I've just realized that we should probably do this fast because of
reflection. We should force "char"-based strings obtained via reflection
to contain UTF-8 and wchar_t (should we even allow wchar_t during
reflection?) be UTF-32.