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Rollup merge of #110237 - oli-obk:impl_trait_in_assoc_tys, r=jackh726

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Split out a separate feature gate for impl trait in associated types

in https://github.com/rust-lang/rust/issues/107645 it was decided that we'll take a new route for type alias impl trait. The exact route isn't clear yet, so while I'm working on implementing some of these proposed changes (e.g. in https://github.com/rust-lang/rust/pull/110010) to be able to experiment with them, I will also work on stabilizing another sugar version first: impl trait in associated types. Similarly I'll look into creating feature gates for impl trait in const/static types.

This PR does nothing but split the feature gate, so that you need to enable a different feature gate for

```rust
impl Trait for Type {
    type Assoc = impl SomeTrait;
}
```

than what you need for `type Foo = impl SomeTrait;`
This commit is contained in:
Matthias Krüger 2023-04-12 20:56:24 +02:00 • committed by GitHub
commit 214e4ef4ef
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68 changed files with 217 additions and 148 deletions
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30
compiler/rustc_ast_passes/src/feature_gate.rs
View file

@ -121,24 +121,34 @@ impl<'a> PostExpansionVisitor<'a> {
}
/// Feature gate `impl Trait` inside `type Alias = $type_expr;`.
fn check_impl_trait(&self, ty: &ast::Ty) {
fn check_impl_trait(&self, ty: &ast::Ty, in_associated_ty: bool) {
struct ImplTraitVisitor<'a> {
vis: &'a PostExpansionVisitor<'a>,
in_associated_ty: bool,
}
impl Visitor<'_> for ImplTraitVisitor<'_> {
fn visit_ty(&mut self, ty: &ast::Ty) {
if let ast::TyKind::ImplTrait(..) = ty.kind {
gate_feature_post!(
&self.vis,
type_alias_impl_trait,
ty.span,
"`impl Trait` in type aliases is unstable"
);
if self.in_associated_ty {
gate_feature_post!(
&self.vis,
impl_trait_in_assoc_type,
ty.span,
"`impl Trait` in associated types is unstable"
);
} else {
gate_feature_post!(
&self.vis,
type_alias_impl_trait,
ty.span,
"`impl Trait` in type aliases is unstable"
);
}
}
visit::walk_ty(self, ty);
}
}
ImplTraitVisitor { vis: self }.visit_ty(ty);
ImplTraitVisitor { vis: self, in_associated_ty }.visit_ty(ty);
}
fn check_late_bound_lifetime_defs(&self, params: &[ast::GenericParam]) {
@ -294,7 +304,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
}
ast::ItemKind::TyAlias(box ast::TyAlias { ty: Some(ty), .. }) => {
self.check_impl_trait(&ty)
self.check_impl_trait(&ty, false)
}
_ => {}
@ -520,7 +530,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
);
}
if let Some(ty) = ty {
self.check_impl_trait(ty);
self.check_impl_trait(ty, true);
}
false
}