Efficient single inheritance

Efficient single inheritance via virtual structs and unification and nesting of structs and enums.
when I first saw this nested enum syntax, I was worried that it conflicted with struct-style enum variants; i.e., how does one distinguish the case shown here from `enum Names { Variant1, Variant2(int), VariantNest { x: int } }`

But on reflection, I think part of the *reason* you have picked the syntax shown here and above is precisely that it *supports* (unifies) the struct-variant syntax with your named-field syntax shown above.

You allude to this in the presentation above when you say that this RFC makes struct-variants and tuple-structs less ad-hoc.

I think you should go further and actually add some concrete examples showing how the struct-variant syntax looks and how it is subtly distinguished from the nested enum syntax.