diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
index 7d4df59902a..0fa72ed8241 100644
--- a/compiler/rustc_borrowck/src/type_check/canonical.rs
+++ b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -94,6 +94,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
Some(ty::Binder::dummy(ty::PredicateKind::Trait(ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::NotConst,
+ polarity: ty::ImplPolarity::Positive,
}))),
locations,
category,
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index d704c4335c7..fea2531cc5b 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -825,6 +825,7 @@ impl Visitor<'tcx> for Checker<'mir, 'tcx> {
Binder::dummy(TraitPredicate {
trait_ref,
constness: ty::BoundConstness::ConstIfConst,
+ polarity: ty::ImplPolarity::Positive,
}),
);
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
index 5eb7d7a91cc..71870269b27 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
@@ -137,6 +137,7 @@ impl Qualif for NeedsNonConstDrop {
ty::Binder::dummy(ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::ConstIfConst,
+ polarity: ty::ImplPolarity::Positive,
}),
);
diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
index 08b4d3aecda..d0f5dfbe4b5 100644
--- a/compiler/rustc_middle/src/ty/error.rs
+++ b/compiler/rustc_middle/src/ty/error.rs
@@ -34,6 +34,7 @@ impl<T> ExpectedFound<T> {
pub enum TypeError<'tcx> {
Mismatch,
ConstnessMismatch(ExpectedFound<ty::BoundConstness>),
+ PolarityMismatch(ExpectedFound<ty::ImplPolarity>),
UnsafetyMismatch(ExpectedFound<hir::Unsafety>),
AbiMismatch(ExpectedFound<abi::Abi>),
Mutability,
@@ -104,6 +105,9 @@ impl<'tcx> fmt::Display for TypeError<'tcx> {
ConstnessMismatch(values) => {
write!(f, "expected {} bound, found {} bound", values.expected, values.found)
}
+ PolarityMismatch(values) => {
+ write!(f, "expected {} polarity, found {} polarity", values.expected, values.found)
+ }
UnsafetyMismatch(values) => {
write!(f, "expected {} fn, found {} fn", values.expected, values.found)
}
@@ -212,10 +216,9 @@ impl<'tcx> TypeError<'tcx> {
use self::TypeError::*;
match self {
CyclicTy(_) | CyclicConst(_) | UnsafetyMismatch(_) | ConstnessMismatch(_)
- | Mismatch | AbiMismatch(_) | FixedArraySize(_) | ArgumentSorts(..) | Sorts(_)
- | IntMismatch(_) | FloatMismatch(_) | VariadicMismatch(_) | TargetFeatureCast(_) => {
- false
- }
+ | PolarityMismatch(_) | Mismatch | AbiMismatch(_) | FixedArraySize(_)
+ | ArgumentSorts(..) | Sorts(_) | IntMismatch(_) | FloatMismatch(_)
+ | VariadicMismatch(_) | TargetFeatureCast(_) => false,
Mutability
| ArgumentMutability(_)
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 0eacedc09ee..98354d7844b 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -165,7 +165,18 @@ pub struct ImplHeader<'tcx> {
pub predicates: Vec<Predicate<'tcx>>,
}
-#[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
+#[derive(
+ Copy,
+ Clone,
+ PartialEq,
+ Eq,
+ Hash,
+ TyEncodable,
+ TyDecodable,
+ HashStable,
+ Debug,
+ TypeFoldable
+)]
pub enum ImplPolarity {
/// `impl Trait for Type`
Positive,
@@ -178,6 +189,26 @@ pub enum ImplPolarity {
Reservation,
}
+impl ImplPolarity {
+ pub fn flip(&self) -> Option<ImplPolarity> {
+ match self {
+ ImplPolarity::Positive => Some(ImplPolarity::Negative),
+ ImplPolarity::Negative => Some(ImplPolarity::Positive),
+ ImplPolarity::Reservation => None,
+ }
+ }
+}
+
+impl fmt::Display for ImplPolarity {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ match self {
+ Self::Positive => f.write_str("positive"),
+ Self::Negative => f.write_str("negative"),
+ Self::Reservation => f.write_str("reservation"),
+ }
+ }
+}
+
#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
pub enum Visibility {
/// Visible everywhere (including in other crates).
@@ -460,6 +491,26 @@ impl<'tcx> Predicate<'tcx> {
pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
self.inner.kind
}
+
+ pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
+ let kind = self
+ .inner
+ .kind
+ .map_bound(|kind| match kind {
+ PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
+ Some(PredicateKind::Trait(TraitPredicate {
+ trait_ref,
+ constness,
+ polarity: polarity.flip()?,
+ }))
+ }
+
+ _ => None,
+ })
+ .transpose()?;
+
+ Some(tcx.mk_predicate(kind))
+ }
}
impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
@@ -655,6 +706,8 @@ pub struct TraitPredicate<'tcx> {
pub trait_ref: TraitRef<'tcx>,
pub constness: BoundConstness,
+
+ pub polarity: ImplPolarity,
}
pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
@@ -789,7 +842,11 @@ impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
self.value
.map_bound(|trait_ref| {
- PredicateKind::Trait(ty::TraitPredicate { trait_ref, constness: self.constness })
+ PredicateKind::Trait(ty::TraitPredicate {
+ trait_ref,
+ constness: self.constness,
+ polarity: ty::ImplPolarity::Positive,
+ })
})
.to_predicate(tcx)
}
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index 2c786538014..8b20e1eec9a 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -797,6 +797,20 @@ impl<'tcx> Relate<'tcx> for GenericArg<'tcx> {
}
}
+impl<'tcx> Relate<'tcx> for ty::ImplPolarity {
+ fn relate<R: TypeRelation<'tcx>>(
+ relation: &mut R,
+ a: ty::ImplPolarity,
+ b: ty::ImplPolarity,
+ ) -> RelateResult<'tcx, ty::ImplPolarity> {
+ if a != b {
+ Err(TypeError::PolarityMismatch(expected_found(relation, a, b)))
+ } else {
+ Ok(a)
+ }
+ }
+}
+
impl<'tcx> Relate<'tcx> for ty::TraitPredicate<'tcx> {
fn relate<R: TypeRelation<'tcx>>(
relation: &mut R,
@@ -806,6 +820,7 @@ impl<'tcx> Relate<'tcx> for ty::TraitPredicate<'tcx> {
Ok(ty::TraitPredicate {
trait_ref: relation.relate(a.trait_ref, b.trait_ref)?,
constness: relation.relate(a.constness, b.constness)?,
+ polarity: relation.relate(a.polarity, b.polarity)?,
})
}
}
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 8f343ba9fec..d6069395474 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -157,7 +157,7 @@ impl fmt::Debug for ty::TraitPredicate<'tcx> {
if let ty::BoundConstness::ConstIfConst = self.constness {
write!(f, "~const ")?;
}
- write!(f, "TraitPredicate({:?})", self.trait_ref)
+ write!(f, "TraitPredicate({:?}, polarity:{:?})", self.trait_ref, self.polarity)
}
}
@@ -365,8 +365,11 @@ impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
type Lifted = ty::TraitPredicate<'tcx>;
fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
- tcx.lift(self.trait_ref)
- .map(|trait_ref| ty::TraitPredicate { trait_ref, constness: self.constness })
+ tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate {
+ trait_ref,
+ constness: self.constness,
+ polarity: self.polarity,
+ })
}
}
@@ -591,6 +594,7 @@ impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
Some(match self {
Mismatch => Mismatch,
ConstnessMismatch(x) => ConstnessMismatch(x),
+ PolarityMismatch(x) => PolarityMismatch(x),
UnsafetyMismatch(x) => UnsafetyMismatch(x),
AbiMismatch(x) => AbiMismatch(x),
Mutability => Mutability,
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index d3094b3e6ff..874de3366d7 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -882,6 +882,7 @@ impl<'tcx> PolyTraitRef<'tcx> {
self.map_bound(|trait_ref| ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::NotConst,
+ polarity: ty::ImplPolarity::Positive,
})
}
}
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index ae3a9c71c59..adb5aa3209c 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -124,9 +124,11 @@ where
fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> ControlFlow<V::BreakTy> {
match predicate.kind().skip_binder() {
- ty::PredicateKind::Trait(ty::TraitPredicate { trait_ref, constness: _ }) => {
- self.visit_trait(trait_ref)
- }
+ ty::PredicateKind::Trait(ty::TraitPredicate {
+ trait_ref,
+ constness: _,
+ polarity: _,
+ }) => self.visit_trait(trait_ref),
ty::PredicateKind::Projection(ty::ProjectionPredicate { projection_ty, ty }) => {
ty.visit_with(self)?;
self.visit_projection_ty(projection_ty)
diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index 622c9edc434..6452b520452 100644
--- a/compiler/rustc_trait_selection/src/traits/auto_trait.rs
+++ b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
@@ -286,6 +286,8 @@ impl AutoTraitFinder<'tcx> {
substs: infcx.tcx.mk_substs_trait(ty, &[]),
},
constness: ty::BoundConstness::NotConst,
+ // Auto traits are positive
+ polarity: ty::ImplPolarity::Positive,
}));
let computed_preds = param_env.caller_bounds().iter();
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index b31d6d68b0a..428873b8d3d 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -804,6 +804,7 @@ pub fn vtable_trait_upcasting_coercion_new_vptr_slot(
ty::Binder::dummy(ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::NotConst,
+ polarity: ty::ImplPolarity::Positive,
}),
);
diff --git a/compiler/rustc_trait_selection/src/traits/relationships.rs b/compiler/rustc_trait_selection/src/traits/relationships.rs
index 7751dd84f4c..e0098cc92d5 100644
--- a/compiler/rustc_trait_selection/src/traits/relationships.rs
+++ b/compiler/rustc_trait_selection/src/traits/relationships.rs
@@ -44,6 +44,7 @@ pub(crate) fn update<'tcx, T>(
ty::PredicateKind::Trait(ty::TraitPredicate {
trait_ref,
constness: predicate.constness,
+ polarity: predicate.polarity,
})
})
.to_predicate(infcx.tcx),
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 856ea43b1ff..f0761975c19 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -915,6 +915,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
substs: self.tcx().mk_substs_trait(ty, &[]),
},
constness: ty::BoundConstness::NotConst,
+ polarity: ty::ImplPolarity::Positive,
}));
copy_obligation.recursion_depth = depth + 1;
self.assemble_candidates_from_impls(©_obligation, &mut copy_candidates);
diff --git a/compiler/rustc_typeck/src/check/_match.rs b/compiler/rustc_typeck/src/check/_match.rs
index 6a231e719e6..c17c42c497f 100644
--- a/compiler/rustc_typeck/src/check/_match.rs
+++ b/compiler/rustc_typeck/src/check/_match.rs
@@ -531,6 +531,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
substs: self.infcx.tcx.mk_substs_trait(outer_ty, &[]),
},
constness: t.constness,
+ polarity: t.polarity,
}));
let obl = Obligation::new(
o.cause.clone(),
diff --git a/compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs b/compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs
index f4bb5761c19..4fb422c801b 100644
--- a/compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs
+++ b/compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs
@@ -382,6 +382,7 @@ fn check_specialization_on<'tcx>(tcx: TyCtxt<'tcx>, predicate: ty::Predicate<'tc
ty::PredicateKind::Trait(ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::NotConst,
+ polarity: _,
}) => {
if !matches!(
trait_predicate_kind(tcx, predicate),
@@ -413,6 +414,7 @@ fn trait_predicate_kind<'tcx>(
ty::PredicateKind::Trait(ty::TraitPredicate {
trait_ref,
constness: ty::BoundConstness::NotConst,
+ polarity: _,
}) => Some(tcx.trait_def(trait_ref.def_id).specialization_kind),
ty::PredicateKind::Trait(_)
| ty::PredicateKind::RegionOutlives(_)