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Remove some noise from opaque type errors around associated types

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This commit is contained in:
Oli Scherer 2021-12-16 15:17:16 +00:00
parent f8402169aa
commit 689a868a1f
3 changed files with 17 additions and 57 deletions
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14
compiler/rustc_infer/src/infer/opaque_types.rs
View file

@ -551,6 +551,20 @@ impl<'a, 'tcx> Instantiator<'a, 'tcx> {
let predicate = predicate.subst(tcx, substs);
debug!(?predicate);
// Replace all other mentions of the same opaque type with the hidden type,
// as the bounds must hold on the hidden type after all.
let predicate = predicate.fold_with(&mut BottomUpFolder {
tcx,
ty_op: |ty| match *ty.kind() {
ty::Opaque(def_id2, substs2) if def_id == def_id2 && substs == substs2 => {
ty_var
}
_ => ty,
},
lt_op: |lt| lt,
ct_op: |ct| ct,
});
// We can't normalize associated types from `rustc_infer`, but we can eagerly register inference variables for them.
let predicate = predicate.fold_with(&mut BottomUpFolder {
tcx,

4
src/test/ui/type-alias-impl-trait/bound_reduction2.rs
View file

@ -15,9 +15,5 @@ impl<W> Trait<W> for () {}
fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
//~^ ERROR non-defining opaque type use in defining scope
//~| ERROR non-defining opaque type use in defining scope
//~| ERROR non-defining opaque type use in defining scope
//~| ERROR `T` is part of concrete type but not used in parameter list
//~| ERROR `T` is part of concrete type but not used in parameter list
()
}

56
src/test/ui/type-alias-impl-trait/bound_reduction2.stderr
View file

@ -1,34 +1,8 @@
error: type parameter `T` is part of concrete type but not used in parameter list for the `impl Trait` type alias
--> $DIR/bound_reduction2.rs:16:60
|
LL | fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
| ____________________________________________________________^
LL | |
LL | |
LL | |
... |
LL | | ()
LL | | }
| |_^
error: type parameter `T` is part of concrete type but not used in parameter list for the `impl Trait` type alias
--> $DIR/bound_reduction2.rs:16:60
|
LL | fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
| ____________________________________________________________^
LL | |
LL | |
LL | |
... |
LL | | ()
LL | | }
| |_^
error: non-defining opaque type use in defining scope
--> $DIR/bound_reduction2.rs:16:1
--> $DIR/bound_reduction2.rs:16:46
|
LL | fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^
|
note: used non-generic type `<T as TraitWithAssoc>::Assoc` for generic parameter
--> $DIR/bound_reduction2.rs:9:10
@ -36,35 +10,11 @@ note: used non-generic type `<T as TraitWithAssoc>::Assoc` for generic parameter
LL | type Foo<V> = impl Trait<V>;
| ^
error: non-defining opaque type use in defining scope
--> $DIR/bound_reduction2.rs:16:1
|
LL | fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: used non-generic type `_` for generic parameter
--> $DIR/bound_reduction2.rs:9:10
|
LL | type Foo<V> = impl Trait<V>;
| ^
error: non-defining opaque type use in defining scope
--> $DIR/bound_reduction2.rs:16:1
|
LL | fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: used non-generic type `_` for generic parameter
--> $DIR/bound_reduction2.rs:9:10
|
LL | type Foo<V> = impl Trait<V>;
| ^
error: could not find defining uses
--> $DIR/bound_reduction2.rs:9:15
|
LL | type Foo<V> = impl Trait<V>;
| ^^^^^^^^^^^^^
error: aborting due to 6 previous errors
error: aborting due to 2 previous errors