diff options
Diffstat (limited to 'src/librustc/ty/mod.rs')
| -rw-r--r-- | src/librustc/ty/mod.rs | 51 |
1 files changed, 40 insertions, 11 deletions
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs index 3d1ae838d81..bd5ac5e5ab4 100644 --- a/src/librustc/ty/mod.rs +++ b/src/librustc/ty/mod.rs @@ -167,6 +167,19 @@ pub struct ImplHeader<'tcx> { pub predicates: Vec<Predicate<'tcx>>, } +#[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)] +pub enum ImplPolarity { + /// `impl Trait for Type` + Positive, + /// `impl !Trait for Type` + Negative, + /// `#[rustc_reservation_impl] impl Trait for Type` + /// + /// This is a "stability hack", not a real Rust feature. + /// See #64631 for details. + Reservation, +} + #[derive(Copy, Clone, Debug, PartialEq, HashStable)] pub struct AssocItem { pub def_id: DefId, @@ -2911,7 +2924,26 @@ impl<'tcx> TyCtxt<'tcx> { return Some(ImplOverlapKind::Permitted); } - let is_legit = if self.features().overlapping_marker_traits { + match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) { + (ImplPolarity::Reservation, _) | + (_, ImplPolarity::Reservation) => { + // `#[rustc_reservation_impl]` impls don't overlap with anything + debug!("impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)", + def_id1, def_id2); + return Some(ImplOverlapKind::Permitted); + } + (ImplPolarity::Positive, ImplPolarity::Negative) | + (ImplPolarity::Negative, ImplPolarity::Positive) => { + // `impl AutoTrait for Type` + `impl !AutoTrait for Type` + debug!("impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)", + def_id1, def_id2); + return None; + } + (ImplPolarity::Positive, ImplPolarity::Positive) | + (ImplPolarity::Negative, ImplPolarity::Negative) => {} + }; + + let is_marker_overlap = if self.features().overlapping_marker_traits { let trait1_is_empty = self.impl_trait_ref(def_id1) .map_or(false, |trait_ref| { self.associated_item_def_ids(trait_ref.def_id).is_empty() @@ -2920,22 +2952,19 @@ impl<'tcx> TyCtxt<'tcx> { .map_or(false, |trait_ref| { self.associated_item_def_ids(trait_ref.def_id).is_empty() }); - self.impl_polarity(def_id1) == self.impl_polarity(def_id2) - && trait1_is_empty - && trait2_is_empty + trait1_is_empty && trait2_is_empty } else { let is_marker_impl = |def_id: DefId| -> bool { let trait_ref = self.impl_trait_ref(def_id); trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker) }; - self.impl_polarity(def_id1) == self.impl_polarity(def_id2) - && is_marker_impl(def_id1) - && is_marker_impl(def_id2) + is_marker_impl(def_id1) && is_marker_impl(def_id2) }; - if is_legit { - debug!("impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted)", - def_id1, def_id2); + + if is_marker_overlap { + debug!("impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)", + def_id1, def_id2); Some(ImplOverlapKind::Permitted) } else { if let Some(self_ty1) = self.issue33140_self_ty(def_id1) { @@ -3317,7 +3346,7 @@ fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Ty<'_>> { debug!("issue33140_self_ty({:?}), trait-ref={:?}", def_id, trait_ref); let is_marker_like = - tcx.impl_polarity(def_id) == hir::ImplPolarity::Positive && + tcx.impl_polarity(def_id) == ty::ImplPolarity::Positive && tcx.associated_item_def_ids(trait_ref.def_id).is_empty(); // Check whether these impls would be ok for a marker trait. |