bjoernager/rust
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Document flip polarity

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Santiago Pastorino 2021-10-22 09:34:36 -03:00
parent 7829d9dde3
commit c4c76a4fbd
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2 changed files with 7 additions and 0 deletions
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3
compiler/rustc_infer/src/traits/mod.rs
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@ -56,6 +56,9 @@ pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;
pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>; pub type TraitObligation<'tcx> = Obligation<'tcx, ty::PolyTraitPredicate<'tcx>>;
impl PredicateObligation<'tcx> { impl PredicateObligation<'tcx> {
/// Flips the polarity of the inner predicate.
///
/// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<PredicateObligation<'tcx>> { pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<PredicateObligation<'tcx>> {
Some(PredicateObligation { Some(PredicateObligation {
cause: self.cause.clone(), cause: self.cause.clone(),

4
compiler/rustc_middle/src/ty/mod.rs
View file

@ -190,6 +190,7 @@ pub enum ImplPolarity {
} }
impl ImplPolarity { impl ImplPolarity {
/// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
pub fn flip(&self) -> Option<ImplPolarity> { pub fn flip(&self) -> Option<ImplPolarity> {
match self { match self {
ImplPolarity::Positive => Some(ImplPolarity::Negative), ImplPolarity::Positive => Some(ImplPolarity::Negative),
@ -492,6 +493,9 @@ impl<'tcx> Predicate<'tcx> {
self.inner.kind self.inner.kind
} }
/// Flips the polarity of a Predicate.
///
/// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> { pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
let kind = self let kind = self
.inner .inner