HIR: tracking issue for HIR-related things.

[nrc]

Initial landing: #28138

[nrc]

• HIR: move desugaring to lowering step #28140 move desugaring to lowering step
• HIR: unify literals and attributes #28141 unify literals and attributes
• HIR: delete the AST after lowering #28142 delete the AST after lowering
• HIR: cache lowering info #28143 cache lowering info
• HIR: remove ids from the AST #28144 remove ids from the AST
• HIR: separate AST and HIR lints #28145 separate AST and HIR lints
• HIR: Move lifetime elision to HIR lowering #28644 move lifetime elision to HIR lowering

[eddyb]

cc @rust-lang/compiler

[Manishearth]

We may also want to reexport Ident and NodeId through HIR

[eddyb]

@Manishearth Ident has the overhead of hygiene information, maybe we could use only Name in the HIR (or some sort of general interned string index Symbol - that's just a naming concern though).

And NodeId will probably be split into per-node-type IDs.

[Manishearth]

Yeah, that works. Also we need to reexport Name, forgot about that one.

[steveklabnik]

Triage: this is a metabug. I updated some of @nrc's checkboxes from above.

[nikomatsakis]

I think we can close this bug, the transition to HIR is effectively complete.