Pre-RFC: anonymous struct and union types

[withoutboats]

@josh

No particular reason. It seems quite reasonable to me to allow anonymous types anywhere a type can appear.

(That proposal could support part of this, as long as the approaches involving sorting fields to unify types don't get included, or at least not when declared with repr(C).)

However, I don't want to propose allowing unnamed fields everywhere, only within a struct or union. (And possibly also within an enum variant that uses named fields, for symmetry.)

In the juxtoposition of the two emphasized sentences, it seems like you're drawing a distinction between "anonymous types" and "unnamed fields," but I think they refer to the same idea (which I think is better referred to as "unlabled types," since "anonymous types" is usually used for things like the type of closures). What is the distinction?