bjoernager/rust
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don't assume trait ambiguity happens in Self

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This commit is contained in:
SNCPlay42 2020-10-19 17:42:57 +01:00
parent c38ddb8040
commit 71ca239f80
4 changed files with 113 additions and 34 deletions
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30
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
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@ -1462,9 +1462,8 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
let bound_predicate = predicate.bound_atom();
let mut err = match bound_predicate.skip_binder() {
ty::PredicateAtom::Trait(data, _) => {
let self_ty = data.trait_ref.self_ty();
let trait_ref = bound_predicate.rebind(data.trait_ref);
debug!("self_ty {:?} {:?} trait_ref {:?}", self_ty, self_ty.kind(), trait_ref);
debug!("trait_ref {:?}", trait_ref);
if predicate.references_error() {
return;
@ -1479,6 +1478,17 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
// known, since we don't dispatch based on region
// relationships.
// Pick the first substitution that still contains inference variables as the one
// we're going to emit an error for. If there are none (see above), fall back to
// the substitution for `Self`.
let subst = {
let substs = data.trait_ref.substs;
substs
.iter()
.find(|s| s.has_infer_types_or_consts())
.unwrap_or_else(|| substs[0])
};
// This is kind of a hack: it frequently happens that some earlier
// error prevents types from being fully inferred, and then we get
// a bunch of uninteresting errors saying something like "<generic
@ -1495,21 +1505,11 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
// check upstream for type errors and don't add the obligations to
// begin with in those cases.
if self.tcx.lang_items().sized_trait() == Some(trait_ref.def_id()) {
self.emit_inference_failure_err(
body_id,
span,
self_ty.into(),
ErrorCode::E0282,
)
.emit();
self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0282).emit();
return;
}
let mut err = self.emit_inference_failure_err(
body_id,
span,
self_ty.into(),
ErrorCode::E0283,
);
let mut err =
self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0283);
err.note(&format!("cannot satisfy `{}`", predicate));
if let ObligationCauseCode::ItemObligation(def_id) = obligation.cause.code {
self.suggest_fully_qualified_path(&mut err, def_id, span, trait_ref.def_id());