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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`
This commit is contained in:
bors 2022-12-14 01:19:24 +00:00
commit 918d0ac38e
115 changed files with 632 additions and 674 deletions

View file

@ -241,7 +241,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
};
let kind = match parent_ty.ty.kind() {
&ty::Opaque(def_id, substs) => {
&ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs }) => {
self.tcx.bound_type_of(def_id).subst(self.tcx, substs).kind()
}
kind => kind,
@ -652,7 +652,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
self.fail(location, "`SetDiscriminant`is not allowed until deaggregation");
}
let pty = place.ty(&self.body.local_decls, self.tcx).ty.kind();
if !matches!(pty, ty::Adt(..) | ty::Generator(..) | ty::Opaque(..)) {
if !matches!(pty, ty::Adt(..) | ty::Generator(..) | ty::Alias(ty::Opaque, ..)) {
self.fail(
location,
format!(