rustc_target: rename {Fn,Arg}Type to {Fn,Arg}Abi.

[eddyb]

I was trying to tweak the API of FnType (now FnAbi) and the name kept bothering me.

FnAbi is to a function signature a bit like a layout is to a type, so the name still isn't perfect yet, but at least it doesn't have the misleading Type in it anymore.

If this can't land I think I can continue my original refactor without it, so I'm not strongly attached to it.

r? @nagisa cc @oli-obk

[RalfJung]

ArgAbi is not entirely clear; FnArgAbi would be better as it sets the right context -- that this is about the call ABI, not other aspects of the ABI like memory layout.

FnLayout wouldn't make much sense, or would it?

[RalfJung]

@eddyb said in chat

what makes ArgAbi really bad IMO is that it's used for returns too

Totally strawman proposal: FnInOutAbi.
Finding something direction-agnostic would be better of course, but it is not clear what that would be. FnDomainAbi?^^

[RalfJung]

FnArgRetAbi would be another one that just lists both uses.

[oli-obk]

While I agree that the name may not be perfect, it is strictly an improvement. I don't like the other options, and Arg conveys both input and output arguments, even if the general notion of argument means an input argument. The fact that there are output arguments means to me that Arg by itself is fine.

We can revisit with more detailed naming later if someone comes up with a better name.

@bors r+

[bors]

📌 Commit 8b06209 has been approved by oli-obk

[bors]

⌛ Testing commit 8b06209 with merge 2e4da3c...

[bors]

☀️ Test successful - checks-azure
Approved by: oli-obk
Pushing 2e4da3c to master...