diff options
Diffstat (limited to 'compiler/rustc_infer/src/traits/util.rs')
| -rw-r--r-- | compiler/rustc_infer/src/traits/util.rs | 87 |
1 files changed, 47 insertions, 40 deletions
diff --git a/compiler/rustc_infer/src/traits/util.rs b/compiler/rustc_infer/src/traits/util.rs index cd5bde2a7..c07ff5165 100644 --- a/compiler/rustc_infer/src/traits/util.rs +++ b/compiler/rustc_infer/src/traits/util.rs @@ -116,11 +116,11 @@ pub fn elaborate_predicates_with_span<'tcx>( pub fn elaborate_obligations<'tcx>( tcx: TyCtxt<'tcx>, - mut obligations: Vec<PredicateObligation<'tcx>>, + obligations: Vec<PredicateObligation<'tcx>>, ) -> Elaborator<'tcx> { - let mut visited = PredicateSet::new(tcx); - obligations.retain(|obligation| visited.insert(obligation.predicate)); - Elaborator { stack: obligations, visited } + let mut elaborator = Elaborator { stack: Vec::new(), visited: PredicateSet::new(tcx) }; + elaborator.extend_deduped(obligations); + elaborator } fn predicate_obligation<'tcx>( @@ -132,6 +132,15 @@ fn predicate_obligation<'tcx>( } impl<'tcx> Elaborator<'tcx> { + fn extend_deduped(&mut self, obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>) { + // Only keep those bounds that we haven't already seen. + // This is necessary to prevent infinite recursion in some + // cases. One common case is when people define + // `trait Sized: Sized { }` rather than `trait Sized { }`. + // let visited = &mut self.visited; + self.stack.extend(obligations.into_iter().filter(|o| self.visited.insert(o.predicate))); + } + pub fn filter_to_traits(self) -> FilterToTraits<Self> { FilterToTraits::new(self) } @@ -145,40 +154,34 @@ impl<'tcx> Elaborator<'tcx> { // Get predicates declared on the trait. let predicates = tcx.super_predicates_of(data.def_id()); - let obligations = predicates.predicates.iter().map(|&(mut pred, span)| { - // when parent predicate is non-const, elaborate it to non-const predicates. - if data.constness == ty::BoundConstness::NotConst { - pred = pred.without_const(tcx); - } - - let cause = obligation.cause.clone().derived_cause( - bound_predicate.rebind(data), - |derived| { - traits::ImplDerivedObligation(Box::new( - traits::ImplDerivedObligationCause { - derived, - impl_def_id: data.def_id(), - span, - }, - )) - }, - ); - predicate_obligation( - pred.subst_supertrait(tcx, &bound_predicate.rebind(data.trait_ref)), - obligation.param_env, - cause, - ) - }); + let obligations = + predicates.predicates.iter().enumerate().map(|(index, &(mut pred, span))| { + // when parent predicate is non-const, elaborate it to non-const predicates. + if data.constness == ty::BoundConstness::NotConst { + pred = pred.without_const(tcx); + } + + let cause = obligation.cause.clone().derived_cause( + bound_predicate.rebind(data), + |derived| { + traits::ImplDerivedObligation(Box::new( + traits::ImplDerivedObligationCause { + derived, + impl_or_alias_def_id: data.def_id(), + impl_def_predicate_index: Some(index), + span, + }, + )) + }, + ); + predicate_obligation( + pred.subst_supertrait(tcx, &bound_predicate.rebind(data.trait_ref)), + obligation.param_env, + cause, + ) + }); debug!(?data, ?obligations, "super_predicates"); - - // Only keep those bounds that we haven't already seen. - // This is necessary to prevent infinite recursion in some - // cases. One common case is when people define - // `trait Sized: Sized { }` rather than `trait Sized { }`. - let visited = &mut self.visited; - let obligations = obligations.filter(|o| visited.insert(o.predicate)); - - self.stack.extend(obligations); + self.extend_deduped(obligations); } ty::PredicateKind::WellFormed(..) => { // Currently, we do not elaborate WF predicates, @@ -235,10 +238,9 @@ impl<'tcx> Elaborator<'tcx> { return; } - let visited = &mut self.visited; let mut components = smallvec![]; push_outlives_components(tcx, ty_max, &mut components); - self.stack.extend( + self.extend_deduped( components .into_iter() .filter_map(|component| match component { @@ -278,7 +280,6 @@ impl<'tcx> Elaborator<'tcx> { .map(|predicate_kind| { bound_predicate.rebind(predicate_kind).to_predicate(tcx) }) - .filter(|&predicate| visited.insert(predicate)) .map(|predicate| { predicate_obligation( predicate, @@ -292,6 +293,12 @@ impl<'tcx> Elaborator<'tcx> { // Nothing to elaborate } ty::PredicateKind::Ambiguous => {} + ty::PredicateKind::AliasEq(..) => { + // No + } + ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..)) => { + // Nothing to elaborate + } } } } |