Rename "anonymized types" internally (TyAnon & friends) to "opaque types" (TyOpaque etc.).

[eddyb]

Now that we're settling on "static existentials" for the generalized version of -> impl Trait, I think it's time to retire my original nomenclature and use the official(?) one uniformly in the compiler.

EDIT: going with "opaque", see below.

cc @cramertj @oli-obk @aturon @Centril

[eddyb]

Alternatively, since @varkor protests, I'd be fine with TySome and "some type" in error messages (okay maybe it's just that I find this part amusing).

EDIT: going with "opaque", see below.

[ms2300]

@eddyb Can I take this ticket on? As it'd be the first ticket I'd take here is there anything I should know beyond the contributing.md?

[eddyb]

@varkor wants it to be TyOpaque, so maybe we should do that instead instead of my half-baked ideas.

@ms2300 Seems good! Searching for Anon and anon should find you all of the relevant places in the codebase (you can ignore AnonConst - if you see more that you're not sure about, feel free to ask).

[Centril]

I, like @varkor, would be most happy with TyOpaque instead of vocabulary reminiscent of existential types (e.g. TySome, TyExists, ..)

[ms2300]

Sounds good, I'll let you all know if I have more questions

[ms2300]

So I'm looking into it and AnonConst, AnonPipe, LateBoundAnon, BrAnon, and Anon (in the FileName sense) don't need to be changed right? Really all that needs to be changed is the internal type of Anon -> Opaque which used to be TyAnon correct?

Edit: and corresponding filenames

[varkor]

So I'm looking into it and AnonConst, AnonPipe, LateBoundAnon, BrAnon, and Anon (in the FileName sense) don't need to be changed right?

That's right.

Really all that needs to be changed is the internal type of Anon -> Opaque which used to be TyAnon correct?

Yes, and anything that might refer to TyAnon as an "anonymous type" (for example in error messages or diagnostics), as well as variable and function names, such as anything containing anon_ty, or mk_anon, etc. It's quite hard to find all of these, but if you search for anon (case insensitive, but possibly mid-word), you should find most of them.

[ms2300]

I just opened a pr to fix this issue -> #53705