Rename UnevaluatedConst to AliasConst

[Shourya742]

refer: rust-lang/project-const-generics#115

r? @khyperia

I only renamed the type system version to AliasConst/AliasConstKind. I did not rename MIR’s UnevaluatedConst, it currently holds direct def_id instead of kind variant we have in type-system. I also left rustc_public’s UnevaluatedConst unchanged.

[rustbot]

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a, @makai410

changes to the core type system

cc @lcnr

Some changes occurred in const_evaluatable.rs

cc @BoxyUwU

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

Some changes occurred in match checking

cc @Nadrieril

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

Some changes occurred in rustc_ty_utils::consts.rs

cc @BoxyUwU

HIR ty lowering was modified

cc @fmease

changes to the core type system

cc @lcnr

[rustbot]

Failed to set assignee to khyperia: invalid assignee

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[khyperia]

thanks so much for working on this! ❤️

there's some more stuff that we want to rename related to this change (sorry for not being more clear in the issue description!):

• ConstKind::Unevaluated (variant that just holds a UnevaluatedConst, its name should reflect what it contains)
• Const::new_unevaluated (constructor for the previous variant)
  • (and the Interner trait for new_unevaluated)
• Interner::UnevaluatedConstId (this one is a bit sketch, I believe it's actually only used for anon consts, not all AliasConsts, so it should possibly be renamed to AnonConstId instead of AliasConstId. Please double check for me though and make a judgement call!)
• perhaps little things like AliasTerm::to_term has a local named unevaluated_const, some other places also call local variables unevaluated. This is less important though, IMO!
  • same thing that we have a relatively consistent naming that variables of type UnevaluatedConst are called uv, could possibly rename those as uv no longer makes sense. But, it's not as important, we can also clean this up over time, IMO.
• lots of comments referring to Unevaluated that could be rephrased if you'd like (it'd be nice to not have to know the legacy information that these things used to be called unevaluated consts while reading comments, but not strictly necessary to update I suppose)
• I need to remember to update the rustc dev guide (but honestly that's on me, that page is pretty out of date after my recent refactorings, I've been forgetting to update it)

I discovered the above list by running rg -i unevaluated in compiler/, and being like, "hmm, does this mention of the word 'unevaluated' have to do with the concept of UnevaluatedConst, or is it just talking about something in general being unevaluated? (and ignoring mir and rustc_public's UnevaluatedConst)". (Just letting you know so you can do the same kind of thing if you'd like! I might have missed some stuff)

Would you like to work on all this other stuff in phases, or would you rather do everything in one big PR? Up to you I think!

[Shourya742]

Would you like to work on all this other stuff in phases, or would you rather do everything in one big PR? Up to you I think!

Thanks for thorough review and suggestions. I would like to get them in, in this PR itself (would be scary to ping these many people again). I will make sure to add commits for each update for easier review. I will reach out, if I have some doubts. Thanks.