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dropck

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This commit is contained in:
Ellen 2021-08-04 18:30:41 +01:00
parent 7f3dc04644
commit b1d14ef08f
2 changed files with 31 additions and 4 deletions
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19
compiler/rustc_typeck/src/check/dropck.rs
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@ -217,10 +217,10 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
// repeated `.iter().any(..)` calls.
// This closure is a more robust way to check `Predicate` equality
// than simple `==` checks (which were the previous implementation).
// It relies on `ty::relate` for `TraitPredicate` and `ProjectionPredicate`
// (which implement the Relate trait), while delegating on simple equality
// for the other `Predicate`.
// than simple `==` checks (which were the previous implementation). It relies on
// `ty::relate` for `TraitPredicate`, `ProjectionPredicate`, `ConstEvaluatable`
// `TypeOutlives` and `TypeWellFormedFromEnv` (which implement the Relate trait),
// while delegating on simple equality for the other `Predicate`.
// This implementation solves (Issue #59497) and (Issue #58311).
// It is unclear to me at the moment whether the approach based on `relate`
// could be extended easily also to the other `Predicate`.
@ -235,6 +235,17 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
(ty::PredicateKind::Projection(a), ty::PredicateKind::Projection(b)) => {
relator.relate(predicate.rebind(a), p.rebind(b)).is_ok()
}
(
ty::PredicateKind::ConstEvaluatable(def_a, substs_a),
ty::PredicateKind::ConstEvaluatable(def_b, substs_b),
) => tcx.try_unify_abstract_consts(((def_a, substs_a), (def_b, substs_b))),
(ty::PredicateKind::TypeOutlives(a), ty::PredicateKind::TypeOutlives(b)) => {
relator.relate(predicate.rebind(a.0), p.rebind(b.0)).is_ok()
}
(
ty::PredicateKind::TypeWellFormedFromEnv(a),
ty::PredicateKind::TypeWellFormedFromEnv(b),
) => relator.relate(predicate.rebind(a), p.rebind(b)).is_ok(),
_ => predicate == p,
}
};

16
src/test/ui/const-generics/const_evaluatable_checked/drop_impl.rs Normal file
View file

@ -0,0 +1,16 @@
//check-pass
#![feature(const_generics, const_evaluatable_checked)]
#![allow(incomplete_features)]
struct Foo<const N: usize>
where
[(); N + 1]: ;
impl<const N: usize> Drop for Foo<N>
where
[(); N + 1]: ,
{
fn drop(&mut self) {}
}
fn main() {}