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Fix associate type diagnostics

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This commit is contained in:
XIAO Tian 2020-05-30 11:26:46 +08:00
parent 3bf9eb0f7a
commit 1a68c8e8d9
1 changed files with 12 additions and 19 deletions
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31
src/librustc_trait_selection/traits/wf.rs
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@ -172,25 +172,18 @@ fn extend_cause_with_original_assoc_item_obligation<'tcx>(
};
match pred.kind() {
ty::PredicateKind::Projection(proj) => {
// The obligation comes not from the current `impl` nor the `trait` being
// implemented, but rather from a "second order" obligation, like in
// `src/test/ui/associated-types/point-at-type-on-obligation-failure.rs`.
let trait_assoc_item = tcx.associated_item(proj.projection_def_id());
if let Some(impl_item_span) =
items.iter().find(|item| item.ident == trait_assoc_item.ident).map(fix_span)
{
cause.span = impl_item_span;
} else {
let kind = &proj.ty().skip_binder().kind;
if let ty::Projection(projection_ty) = kind {
// This happens when an associated type has a projection coming from another
// associated type. See `traits-assoc-type-in-supertrait-bad.rs`.
let trait_assoc_item = tcx.associated_item(projection_ty.item_def_id);
if let Some(impl_item_span) =
items.iter().find(|item| item.ident == trait_assoc_item.ident).map(fix_span)
{
cause.span = impl_item_span;
}
// The obligation comes not from the current `impl` nor the `trait` being implemented,
// but rather from a "second order" obligation, where an associated type has a
// projection coming from another associated type. See
// `src/test/ui/associated-types/point-at-type-on-obligation-failure.rs` and
// `traits-assoc-type-in-supertrait-bad.rs`.
let kind = &proj.ty().skip_binder().kind;
if let ty::Projection(projection_ty) = kind {
let trait_assoc_item = tcx.associated_item(projection_ty.item_def_id);
if let Some(impl_item_span) =
items.iter().find(|item| item.ident == trait_assoc_item.ident).map(fix_span)
{
cause.span = impl_item_span;
}
}
}