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Point at overlapping impls when type annotations are needed

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This commit is contained in:
Esteban Kuber
2021-10-01 13:05:17 +00:00
parent ed08a67566
commit ef212e7fb3
29 changed files with 629 additions and 88 deletions
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12
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View File

@@ -18,7 +18,7 @@ use crate::traits;
use crate::traits::coherence::Conflict;
use crate::traits::query::evaluate_obligation::InferCtxtExt;
use crate::traits::{util, SelectionResult};
use crate::traits::{ErrorReporting, Overflow, Unimplemented};
use crate::traits::{Ambiguous, ErrorReporting, Overflow, Unimplemented};
use super::BuiltinImplConditions;
use super::IntercrateAmbiguityCause;
@@ -197,7 +197,15 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// and report ambiguity.
if i > 1 {
debug!("multiple matches, ambig");
return Ok(None);
return Err(Ambiguous(
candidates
.into_iter()
.filter_map(|c| match c.candidate {
SelectionCandidate::ImplCandidate(def_id) => Some(def_id),
_ => None,
})
.collect(),
));
}
}
}

23
compiler/rustc_trait_selection/src/traits/select/mod.rs
View File

@@ -357,18 +357,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
&mut self,
obligation: &TraitObligation<'tcx>,
) -> SelectionResult<'tcx, Selection<'tcx>> {
debug_assert!(!obligation.predicate.has_escaping_bound_vars());
let pec = &ProvisionalEvaluationCache::default();
let stack = self.push_stack(TraitObligationStackList::empty(pec), obligation);
let candidate = match self.candidate_from_obligation(&stack) {
let candidate = match self.select_from_obligation(obligation) {
Err(SelectionError::Overflow) => {
// In standard mode, overflow must have been caught and reported
// earlier.
assert!(self.query_mode == TraitQueryMode::Canonical);
return Err(SelectionError::Overflow);
}
Err(SelectionError::Ambiguous(_)) => {
return Ok(None);
}
Err(e) => {
return Err(e);
}
@@ -391,6 +389,18 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
}
}
crate fn select_from_obligation(
&mut self,
obligation: &TraitObligation<'tcx>,
) -> SelectionResult<'tcx, SelectionCandidate<'tcx>> {
debug_assert!(!obligation.predicate.has_escaping_bound_vars());
let pec = &ProvisionalEvaluationCache::default();
let stack = self.push_stack(TraitObligationStackList::empty(pec), obligation);
self.candidate_from_obligation(&stack)
}
///////////////////////////////////////////////////////////////////////////
// EVALUATION
//
@@ -915,6 +925,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
match self.candidate_from_obligation(stack) {
Ok(Some(c)) => self.evaluate_candidate(stack, &c),
Err(SelectionError::Ambiguous(_)) => Ok(EvaluatedToAmbig),
Ok(None) => Ok(EvaluatedToAmbig),
Err(Overflow) => Err(OverflowError::Canonical),
Err(ErrorReporting) => Err(OverflowError::ErrorReporting),