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Point at the Sized obligation in where clauses

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This commit is contained in:
Esteban Küber 2020-01-29 13:27:53 -08:00
parent 4b2f1db6e4
commit 972ae5afe5
3 changed files with 41 additions and 7 deletions
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39
src/librustc/traits/object_safety.rs
View file

@ -234,17 +234,48 @@ fn get_sized_bounds(tcx: TyCtxt<'_>, trait_def_id: DefId) -> SmallVec<[Span; 1]>
tcx.hir()
.get_if_local(trait_def_id)
.and_then(|node| match node {
hir::Node::Item(hir::Item { kind: hir::ItemKind::Trait(.., bounds, _), .. }) => Some(
bounds
hir::Node::Item(hir::Item {
kind: hir::ItemKind::Trait(.., generics, bounds, _),
..
}) => Some(
generics
.where_clause
.predicates
.iter()
.filter_map(|b| match b {
.filter_map(|pred| {
match pred {
hir::WherePredicate::BoundPredicate(pred)
if pred.bounded_ty.hir_id.owner_def_id() == trait_def_id =>
{
// Fetch spans for trait bounds that are Sized:
// `trait T where Self: Pred`
Some(pred.bounds.iter().filter_map(|b| match b {
hir::GenericBound::Trait(
trait_ref,
hir::TraitBoundModifier::None,
) if trait_has_sized_self(
tcx,
trait_ref.trait_ref.trait_def_id(),
) =>
{
Some(trait_ref.span)
}
_ => None,
}))
}
_ => None,
}
})
.flatten()
.chain(bounds.iter().filter_map(|b| match b {
hir::GenericBound::Trait(trait_ref, hir::TraitBoundModifier::None)
if trait_has_sized_self(tcx, trait_ref.trait_ref.trait_def_id()) =>
{
// Fetch spans for supertraits that are `Sized`: `trait T: Super`
Some(trait_ref.span)
}
_ => None,
})
}))
.collect::<SmallVec<[Span; 1]>>(),
),
_ => None,

5
src/test/ui/object-safety/object-safety-sized-2.curr.stderr
View file

@ -1,10 +1,11 @@
error[E0038]: the trait `Bar` cannot be made into an object
--> $DIR/object-safety-sized-2.rs:14:30
|
LL | where Self : Sized
| ----- the trait cannot require that `Self : Sized`
...
LL | fn make_bar<T:Bar>(t: &T) -> &dyn Bar {
| ^^^^^^^^ the trait `Bar` cannot be made into an object
|
= note: the trait cannot require that `Self : Sized`
error: aborting due to previous error

4
src/test/ui/object-safety/object-safety-sized-2.object_safe_for_dispatch.stderr
View file

@ -1,10 +1,12 @@
error[E0038]: the trait `Bar` cannot be made into an object
--> $DIR/object-safety-sized-2.rs:16:5
|
LL | where Self : Sized
| ----- the trait cannot require that `Self : Sized`
...
LL | t
| ^ the trait `Bar` cannot be made into an object
|
= note: the trait cannot require that `Self : Sized`
= note: required because of the requirements on the impl of `std::ops::CoerceUnsized<&dyn Bar>` for `&T`
= note: required by cast to type `&dyn Bar`