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Auto merge of #104986 - compiler-errors:opaques, r=oli-obk

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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
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18
compiler/rustc_privacy/src/lib.rs
View file

@ -88,10 +88,7 @@ trait DefIdVisitor<'tcx> {
fn visit_trait(&mut self, trait_ref: TraitRef<'tcx>) -> ControlFlow<Self::BreakTy> {
self.skeleton().visit_trait(trait_ref)
}
fn visit_projection_ty(
&mut self,
projection: ty::ProjectionTy<'tcx>,
) -> ControlFlow<Self::BreakTy> {
fn visit_projection_ty(&mut self, projection: ty::AliasTy<'tcx>) -> ControlFlow<Self::BreakTy> {
self.skeleton().visit_projection_ty(projection)
}
fn visit_predicates(
@ -118,18 +115,15 @@ where
if self.def_id_visitor.shallow() { ControlFlow::CONTINUE } else { substs.visit_with(self) }
}
fn visit_projection_ty(
&mut self,
projection: ty::ProjectionTy<'tcx>,
) -> ControlFlow<V::BreakTy> {
fn visit_projection_ty(&mut self, projection: ty::AliasTy<'tcx>) -> ControlFlow<V::BreakTy> {
let tcx = self.def_id_visitor.tcx();
let (trait_ref, assoc_substs) = if tcx.def_kind(projection.item_def_id)
let (trait_ref, assoc_substs) = if tcx.def_kind(projection.def_id)
!= DefKind::ImplTraitPlaceholder
{
projection.trait_ref_and_own_substs(tcx)
} else {
// HACK(RPITIT): Remove this when RPITITs are lowered to regular assoc tys
let def_id = tcx.impl_trait_in_trait_parent(projection.item_def_id);
let def_id = tcx.impl_trait_in_trait_parent(projection.def_id);
let trait_generics = tcx.generics_of(def_id);
(
ty::TraitRef { def_id, substs: projection.substs.truncate_to(tcx, trait_generics) },
@ -214,7 +208,7 @@ where
}
}
}
ty::Projection(proj) => {
ty::Alias(ty::Projection, proj) => {
if self.def_id_visitor.skip_assoc_tys() {
// Visitors searching for minimal visibility/reachability want to
// conservatively approximate associated types like `<Type as Trait>::Alias`
@ -241,7 +235,7 @@ where
self.def_id_visitor.visit_def_id(def_id, "trait", &trait_ref)?;
}
}
ty::Opaque(def_id, ..) => {
ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs: _ }) => {
// Skip repeated `Opaque`s to avoid infinite recursion.
if self.visited_opaque_tys.insert(def_id) {
// The intent is to treat `impl Trait1 + Trait2` identically to