diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs')
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs b/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs index d5d7681a8d6..364a13b3a75 100644 --- a/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs +++ b/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs @@ -1,12 +1,8 @@ -//! "Object safety" refers to the ability for a trait to be converted -//! to an object. In general, traits may only be converted to an -//! object if all of their methods meet certain criteria. In particular, -//! they must: +//! "Dyn-compatibility"[^1] refers to the ability for a trait to be converted +//! to a trait object. In general, traits may only be converted to a trait +//! object if certain criteria are met. //! -//! - have a suitable receiver from which we can extract a vtable and coerce to a "thin" version -//! that doesn't contain the vtable; -//! - not reference the erased type `Self` except for in this receiver; -//! - not have generic type parameters. +//! [^1]: Formerly known as "object safety". use std::iter; use std::ops::ControlFlow; @@ -129,7 +125,7 @@ fn sized_trait_bound_spans<'tcx>( bounds: hir::GenericBounds<'tcx>, ) -> impl 'tcx + Iterator<Item = Span> { bounds.iter().filter_map(move |b| match b { - hir::GenericBound::Trait(trait_ref, hir::TraitBoundModifier::None) + hir::GenericBound::Trait(trait_ref) if trait_has_sized_self( tcx, trait_ref.trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise()), @@ -506,8 +502,8 @@ fn virtual_call_violations_for_method<'tcx>( /// This code checks that `receiver_is_dispatchable` is correctly implemented. /// -/// This check is outlined from the object safety check to avoid cycles with -/// layout computation, which relies on knowing whether methods are object safe. +/// This check is outlined from the dyn-compatibility check to avoid cycles with +/// layout computation, which relies on knowing whether methods are dyn-compatible. fn check_receiver_correct<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId, method: ty::AssocItem) { if !is_vtable_safe_method(tcx, trait_def_id, method) { return; @@ -643,8 +639,8 @@ fn object_ty_for_trait<'tcx>( /// contained by the trait object, because the object that needs to be coerced is behind /// a pointer. /// -/// In practice, we cannot use `dyn Trait` explicitly in the obligation because it would result -/// in a new check that `Trait` is object safe, creating a cycle (until object_safe_for_dispatch +/// In practice, we cannot use `dyn Trait` explicitly in the obligation because it would result in +/// a new check that `Trait` is dyn-compatible, creating a cycle (until dyn_compatible_for_dispatch /// is stabilized, see tracking issue <https://github.com/rust-lang/rust/issues/43561>). /// Instead, we fudge a little by introducing a new type parameter `U` such that /// `Self: Unsize<U>` and `U: Trait + ?Sized`, and use `U` in place of `dyn Trait`. @@ -678,7 +674,7 @@ fn receiver_is_dispatchable<'tcx>( // the type `U` in the query // use a bogus type parameter to mimic a forall(U) query using u32::MAX for now. - // FIXME(mikeyhew) this is a total hack. Once object_safe_for_dispatch is stabilized, we can + // FIXME(mikeyhew) this is a total hack. Once dyn_compatible_for_dispatch is stabilized, we can // replace this with `dyn Trait` let unsized_self_ty: Ty<'tcx> = Ty::new_param(tcx, u32::MAX, Symbol::intern("RustaceansAreAwesome")); @@ -865,7 +861,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for IllegalSelfTypeVisitor<'tcx> { } fn visit_const(&mut self, ct: ty::Const<'tcx>) -> Self::Result { - // Constants can only influence object safety if they are generic and reference `Self`. + // Constants can only influence dyn-compatibility if they are generic and reference `Self`. // This is only possible for unevaluated constants, so we walk these here. self.tcx.expand_abstract_consts(ct).super_visit_with(self) } |
