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Consider negative polarity on overlap check

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Santiago Pastorino 2021-10-12 12:11:00 -03:00
parent 6975afd141
commit 8b0bfb0dcb
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6 changed files with 46 additions and 19 deletions
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29
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -1107,10 +1107,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
// const impl
ImplCandidate(def_id) if tcx.impl_constness(def_id) == hir::Constness::Const => {}
// const param
ParamCandidate(ty::ConstnessAnd {
constness: ty::BoundConstness::ConstIfConst,
..
}) => {}
ParamCandidate((
ty::ConstnessAnd { constness: ty::BoundConstness::ConstIfConst, .. },
_,
)) => {}
// auto trait impl
AutoImplCandidate(..) => {}
// generator, this will raise error in other places
@ -1219,14 +1219,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
if self.can_use_global_caches(param_env) {
if let Some(res) = tcx
.selection_cache
.get(&param_env.and(trait_ref).with_constness(pred.constness), tcx)
.get(&(param_env.and(trait_ref).with_constness(pred.constness), pred.polarity), tcx)
{
return Some(res);
}
}
self.infcx
.selection_cache
.get(&param_env.and(trait_ref).with_constness(pred.constness), tcx)
.get(&(param_env.and(trait_ref).with_constness(pred.constness), pred.polarity), tcx)
}
/// Determines whether can we safely cache the result
@ -1286,7 +1286,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
debug!(?trait_ref, ?candidate, "insert_candidate_cache global");
// This may overwrite the cache with the same value.
tcx.selection_cache.insert(
param_env.and(trait_ref).with_constness(pred.constness),
(param_env.and(trait_ref).with_constness(pred.constness), pred.polarity),
dep_node,
candidate,
);
@ -1297,7 +1297,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
debug!(?trait_ref, ?candidate, "insert_candidate_cache local");
self.infcx.selection_cache.insert(
param_env.and(trait_ref).with_constness(pred.constness),
(param_env.and(trait_ref).with_constness(pred.constness), pred.polarity),
dep_node,
candidate,
);
@ -1523,10 +1523,14 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
| ConstDropCandidate,
) => false,
(ParamCandidate(other), ParamCandidate(victim)) => {
(
ParamCandidate((other, other_polarity)),
ParamCandidate((victim, victim_polarity)),
) => {
let same_except_bound_vars = other.value.skip_binder()
== victim.value.skip_binder()
&& other.constness == victim.constness
&& other_polarity == victim_polarity
&& !other.value.skip_binder().has_escaping_bound_vars();
if same_except_bound_vars {
// See issue #84398. In short, we can generate multiple ParamCandidates which are
@ -1537,6 +1541,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
other.value.bound_vars().len() <= victim.value.bound_vars().len()
} else if other.value == victim.value
&& victim.constness == ty::BoundConstness::NotConst
&& other_polarity == victim_polarity
{
// Drop otherwise equivalent non-const candidates in favor of const candidates.
true
@ -1566,11 +1571,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
| TraitAliasCandidate(..)
| ObjectCandidate(_)
| ProjectionCandidate(_),
) => !is_global(&cand.value),
) => !is_global(&cand.0.value),
(ObjectCandidate(_) | ProjectionCandidate(_), ParamCandidate(ref cand)) => {
// Prefer these to a global where-clause bound
// (see issue #50825).
is_global(&cand.value)
is_global(&cand.0.value)
}
(
ImplCandidate(_)
@ -1586,7 +1591,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
) => {
// Prefer these to a global where-clause bound
// (see issue #50825).
is_global(&cand.value) && other.evaluation.must_apply_modulo_regions()
is_global(&cand.0.value) && other.evaluation.must_apply_modulo_regions()
}
(ProjectionCandidate(i), ProjectionCandidate(j))