From f75361fec7aecfcede9cf6f0b97f2b1e7756e47b Mon Sep 17 00:00:00 2001 From: Oli Scherer Date: Tue, 9 Jan 2024 11:28:05 +0000 Subject: [PATCH] Limit impl trait in assoc type defining scope --- compiler/rustc_ty_utils/src/opaque_types.rs | 80 ++++++++++++++++++- .../hidden_behind_struct_field2.rs | 8 +- .../hidden_behind_struct_field2.stderr | 15 ++++ 3 files changed, 98 insertions(+), 5 deletions(-) create mode 100644 tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.stderr diff --git a/compiler/rustc_ty_utils/src/opaque_types.rs b/compiler/rustc_ty_utils/src/opaque_types.rs index 1d9c0405b7d..ef67317a601 100644 --- a/compiler/rustc_ty_utils/src/opaque_types.rs +++ b/compiler/rustc_ty_utils/src/opaque_types.rs @@ -275,11 +275,89 @@ impl<'tcx> TypeVisitor> for OpaqueTypeCollector<'tcx> { } } +struct ImplTraitInAssocTypeCollector<'tcx>(OpaqueTypeCollector<'tcx>); + +impl<'tcx> super::sig_types::SpannedTypeVisitor<'tcx> for ImplTraitInAssocTypeCollector<'tcx> { + #[instrument(skip(self), ret, level = "trace")] + fn visit(&mut self, span: Span, value: impl TypeVisitable>) -> ControlFlow { + let old = self.0.span; + self.0.span = Some(span); + value.visit_with(self); + self.0.span = old; + + ControlFlow::Continue(()) + } +} + +impl<'tcx> TypeVisitor> for ImplTraitInAssocTypeCollector<'tcx> { + #[instrument(skip(self), ret, level = "trace")] + fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow { + t.super_visit_with(self)?; + match t.kind() { + ty::Alias(ty::Opaque, alias_ty) if alias_ty.def_id.is_local() => { + self.0.visit_opaque_ty(alias_ty); + } + ty::Alias(ty::Projection, alias_ty) => { + // This avoids having to do normalization of `Self::AssocTy` by only + // supporting the case of a method defining opaque types from assoc types + // in the same impl block. + let parent_trait_ref = self + .0 + .parent_trait_ref() + .expect("impl trait in assoc type collector used on non-assoc item"); + // If the trait ref of the associated item and the impl differs, + // then we can't use the impl's identity substitutions below, so + // just skip. + if alias_ty.trait_ref(self.0.tcx) == parent_trait_ref { + let parent = self.0.parent().expect("we should have a parent here"); + + for &assoc in self.0.tcx.associated_items(parent).in_definition_order() { + trace!(?assoc); + if assoc.trait_item_def_id != Some(alias_ty.def_id) { + continue; + } + + // If the type is further specializable, then the type_of + // is not actually correct below. + if !assoc.defaultness(self.0.tcx).is_final() { + continue; + } + + let impl_args = alias_ty.args.rebase_onto( + self.0.tcx, + parent_trait_ref.def_id, + ty::GenericArgs::identity_for_item(self.0.tcx, parent), + ); + + if check_args_compatible(self.0.tcx, assoc, impl_args) { + return self + .0 + .tcx + .type_of(assoc.def_id) + .instantiate(self.0.tcx, impl_args) + .visit_with(self); + } else { + self.0.tcx.dcx().span_delayed_bug( + self.0.tcx.def_span(assoc.def_id), + "item had incorrect args", + ); + } + } + } + } + _ => trace!(kind=?t.kind()), + } + ControlFlow::Continue(()) + } +} + fn impl_trait_in_assoc_types_defined_by<'tcx>( tcx: TyCtxt<'tcx>, item: LocalDefId, ) -> &'tcx ty::List { - opaque_types_defined_by(tcx, item) + let mut collector = ImplTraitInAssocTypeCollector(OpaqueTypeCollector::new(tcx, item)); + super::sig_types::walk_types(tcx, item, &mut collector); + tcx.mk_local_def_ids(&collector.0.opaques) } fn opaque_types_defined_by<'tcx>( diff --git a/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.rs b/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.rs index e440dce5e51..4c881dd1330 100644 --- a/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.rs +++ b/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.rs @@ -1,9 +1,8 @@ -//! This test shows that we can even follow projections -//! into associated types of the same impl if they are -//! indirectly mentioned in a struct field. +//! This test shows that we do not treat opaque types +//! as defined by a method if the opaque type is +//! only indirectly mentioned in a struct field. #![feature(impl_trait_in_assoc_type)] -// check-pass struct Bar; @@ -16,6 +15,7 @@ impl Trait for Bar { type Assoc = impl std::fmt::Debug; fn foo() -> Foo { Foo { field: () } + //~^ ERROR: item constrains opaque type that is not in its signature } } diff --git a/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.stderr b/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.stderr new file mode 100644 index 00000000000..5c53dfa3a75 --- /dev/null +++ b/tests/ui/type-alias-impl-trait/hidden_behind_struct_field2.stderr @@ -0,0 +1,15 @@ +error: item constrains opaque type that is not in its signature + --> $DIR/hidden_behind_struct_field2.rs:17:22 + | +LL | Foo { field: () } + | ^^ + | + = note: this item must mention the opaque type in its signature in order to be able to register hidden types +note: this item must mention the opaque type in its signature in order to be able to register hidden types + --> $DIR/hidden_behind_struct_field2.rs:16:8 + | +LL | fn foo() -> Foo { + | ^^^ + +error: aborting due to 1 previous error +