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918d0ac38e
rust/compiler/rustc_codegen_ssa
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bors 918d0ac38e Auto merge of #104986 - compiler-errors:opaques, r=oli-obk 
Combine `ty::Projection` and `ty::Opaque` into `ty::Alias`

Implements https://github.com/rust-lang/types-team/issues/79.

This PR consolidates `ty::Projection` and `ty::Opaque` into a single `ty::Alias`, with an `AliasKind` and `AliasTy` type (renamed from `ty::ProjectionTy`, which is the inner data of `ty::Projection`) defined as so:

```
enum AliasKind {
  Projection,
  Opaque,
}

struct AliasTy<'tcx> {
  def_id: DefId,
  substs: SubstsRef<'tcx>,
}
```

Since we don't have access to `TyCtxt` in type flags computation, and because repeatedly calling `DefKind` on the def-id is expensive, these two types are distinguished with `ty::AliasKind`, conveniently glob-imported into `ty::{Projection, Opaque}`. For example:

```diff
  match ty.kind() {
-   ty::Opaque(..) =>
+   ty::Alias(ty::Opaque, ..) => {}
    _ => {}
  }
```

This PR also consolidates match arms that treated `ty::Opaque` and `ty::Projection` identically.

r? `@ghost`
2022-12-14 01:19:24 +00:00
..
src Auto merge of #104986 - compiler-errors:opaques, r=oli-obk 2022-12-14 01:19:24 +00:00
Cargo.toml Rewrite LLVM's archive writer in Rust 2022-11-26 19:35:32 +00:00
README.md

README.md

Please read the rustc-dev-guide chapter on Backend Agnostic Codegen.