rust-clippy/doc
Nicholas Nethercote 5fa961b951 Overhaul TyS and Ty.
Specifically, change `Ty` from this:
```
pub type Ty<'tcx> = &'tcx TyS<'tcx>;
```
to this
```
pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
```
There are two benefits to this.
- It's now a first class type, so we can define methods on it. This
  means we can move a lot of methods away from `TyS`, leaving `TyS` as a
  barely-used type, which is appropriate given that it's not meant to
  be used directly.
- The uniqueness requirement is now explicit, via the `Interned` type.
  E.g. the pointer-based `Eq` and `Hash` comes from `Interned`, rather
  than via `TyS`, which wasn't obvious at all.

Much of this commit is boring churn. The interesting changes are in
these files:
- compiler/rustc_middle/src/arena.rs
- compiler/rustc_middle/src/mir/visit.rs
- compiler/rustc_middle/src/ty/context.rs
- compiler/rustc_middle/src/ty/mod.rs

Specifically:
- Most mentions of `TyS` are removed. It's very much a dumb struct now;
  `Ty` has all the smarts.
- `TyS` now has `crate` visibility instead of `pub`.
- `TyS::make_for_test` is removed in favour of the static `BOOL_TY`,
  which just works better with the new structure.
- The `Eq`/`Ord`/`Hash` impls are removed from `TyS`. `Interned`s impls
  of `Eq`/`Hash` now suffice. `Ord` is now partly on `Interned`
  (pointer-based, for the `Equal` case) and partly on `TyS`
  (contents-based, for the other cases).
- There are many tedious sigil adjustments, i.e. adding or removing `*`
  or `&`. They seem to be unavoidable.
2022-02-15 16:03:24 +11:00
..
adding_lints.md Merge commit 'a5d597637dcb78dc73f93561ce474f23d4177c35' into clippyup 2021-12-06 12:33:31 +01:00
backport.md Merge commit 'bf1c6f9871f430e284b17aa44059e0d0395e28a6' into clippyup 2020-10-23 22:16:59 +02:00
basics.md Merge commit '91496c2ac6abf6454c413bb23e8becf6b6dc20ea' into clippyup 2021-10-21 13:11:36 +02:00
changelog_update.md Merge commit 'a5d597637dcb78dc73f93561ce474f23d4177c35' into clippyup 2021-12-06 12:33:31 +01:00
common_tools_writing_lints.md Overhaul TyS and Ty. 2022-02-15 16:03:24 +11:00
release.md Merge commit '61eb38aeda6cb54b93b872bf503d70084c4d621c' into clippyup 2021-07-01 18:17:38 +02:00
roadmap-2021.md Merge commit '953f024793dab92745fee9cd2c4dee6a60451771' into clippyup 2021-01-15 10:56:44 +01:00