diff --git a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs index 74729ebe4882f..74f381d266116 100644 --- a/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs +++ b/compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs @@ -2060,48 +2060,37 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> { }; match path.res { Res::Def(DefKind::TyParam, _) | Res::SelfTyParam { trait_: _ } => { - // Get the generics of this type's hir owner. This is *different* - // from the generics of the parameter's definition, since we want - // to be able to resolve an RTN path on a nested body (e.g. method - // inside an impl) using the where clauses on the method. - // FIXME(return_type_notation): Think of some better way of doing this. - let Some(generics) = self.tcx.hir_owner_node(hir_id.owner).generics() - else { - return; - }; - - // Look for the first bound that contains an associated type that - // matches the segment that we're looking for. We ignore any subsequent - // bounds since we'll be emitting a hard error in HIR lowering, so this - // is purely speculative. - let one_bound = generics.predicates.iter().find_map(|predicate| { - let hir::WherePredicateKind::BoundPredicate(predicate) = predicate.kind - else { - return None; - }; - let hir::TyKind::Path(hir::QPath::Resolved(None, bounded_path)) = - predicate.bounded_ty.kind - else { - return None; - }; - if bounded_path.res != path.res { - return None; - } - predicate.bounds.iter().find_map(|bound| { - let hir::GenericBound::Trait(trait_) = bound else { - return None; - }; + let mut bounds = + self.for_each_trait_bound_on_res(path.res).filter_map(|trait_def_id| { BoundVarContext::supertrait_hrtb_vars( self.tcx, - trait_.trait_ref.trait_def_id()?, + trait_def_id, item_segment.ident, ty::AssocKind::Fn, ) - }) - }); - let Some((bound_vars, assoc_item)) = one_bound else { + }); + + let Some((bound_vars, assoc_item)) = bounds.next() else { + // This will error in HIR lowering. + self.tcx + .dcx() + .span_delayed_bug(path.span, "no resolution for RTN path"); return; }; + + // Don't bail if we have identical bounds, which may be collected from + // something like `T: Bound + Bound`, or via elaborating supertraits. + for (second_vars, second_assoc_item) in bounds { + if second_vars != bound_vars || second_assoc_item != assoc_item { + // This will error in HIR lowering. + self.tcx.dcx().span_delayed_bug( + path.span, + "ambiguous resolution for RTN path", + ); + return; + } + } + (bound_vars, assoc_item.def_id, item_segment) } // If we have a self type alias (in an impl), try to resolve an @@ -2167,6 +2156,92 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> { existing_bound_vars.extend(bound_vars); self.record_late_bound_vars(item_segment.hir_id, existing_bound_vars_saved); } + + /// Walk the generics of the item for a trait bound whose self type + /// corresponds to the expected res, and return the trait def id. + fn for_each_trait_bound_on_res( + &self, + expected_res: Res, + ) -> impl Iterator + use<'tcx, '_> { + std::iter::from_coroutine( + #[coroutine] + move || { + let mut scope = self.scope; + loop { + let hir_id = match *scope { + Scope::Binder { hir_id, .. } => Some(hir_id), + Scope::Root { opt_parent_item: Some(parent_def_id) } => { + Some(self.tcx.local_def_id_to_hir_id(parent_def_id)) + } + Scope::Body { .. } + | Scope::ObjectLifetimeDefault { .. } + | Scope::Supertrait { .. } + | Scope::TraitRefBoundary { .. } + | Scope::LateBoundary { .. } + | Scope::Opaque { .. } + | Scope::Root { opt_parent_item: None } => None, + }; + + if let Some(hir_id) = hir_id { + let node = self.tcx.hir_node(hir_id); + // If this is a `Self` bound in a trait, yield the trait itself. + // Specifically, we don't need to look at any supertraits since + // we already do that in `BoundVarContext::supertrait_hrtb_vars`. + if let Res::SelfTyParam { trait_: _ } = expected_res + && let hir::Node::Item(item) = node + && let hir::ItemKind::Trait(..) = item.kind + { + // Yield the trait's def id. Supertraits will be + // elaborated from that. + yield item.owner_id.def_id.to_def_id(); + } else if let Some(generics) = node.generics() { + for pred in generics.predicates { + let hir::WherePredicateKind::BoundPredicate(pred) = pred.kind + else { + continue; + }; + let hir::TyKind::Path(hir::QPath::Resolved(None, bounded_path)) = + pred.bounded_ty.kind + else { + continue; + }; + // Match the expected res. + if bounded_path.res != expected_res { + continue; + } + for pred in pred.bounds { + match pred { + hir::GenericBound::Trait(poly_trait_ref) => { + if let Some(def_id) = + poly_trait_ref.trait_ref.trait_def_id() + { + yield def_id; + } + } + hir::GenericBound::Outlives(_) + | hir::GenericBound::Use(_, _) => {} + } + } + } + } + } + + match *scope { + Scope::Binder { s, .. } + | Scope::Body { s, .. } + | Scope::ObjectLifetimeDefault { s, .. } + | Scope::Supertrait { s, .. } + | Scope::TraitRefBoundary { s } + | Scope::LateBoundary { s, .. } + | Scope::Opaque { s, .. } => { + scope = s; + } + Scope::Root { .. } => break, + } + } + }, + ) + } } /// Detects late-bound lifetimes and inserts them into diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs index 0a26b6776bbd5..58223c868c9b6 100644 --- a/compiler/rustc_hir_analysis/src/lib.rs +++ b/compiler/rustc_hir_analysis/src/lib.rs @@ -62,7 +62,9 @@ This API is completely unstable and subject to change. #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")] #![doc(rust_logo)] #![feature(assert_matches)] +#![feature(coroutines)] #![feature(if_let_guard)] +#![feature(iter_from_coroutine)] #![feature(iter_intersperse)] #![feature(let_chains)] #![feature(never_type)] diff --git a/tests/ui/associated-type-bounds/all-generics-lookup.rs b/tests/ui/associated-type-bounds/all-generics-lookup.rs new file mode 100644 index 0000000000000..c5940c14f440c --- /dev/null +++ b/tests/ui/associated-type-bounds/all-generics-lookup.rs @@ -0,0 +1,31 @@ +//@ check-pass + +#![feature(return_type_notation)] + +trait Trait { + fn method(&self) -> impl Sized; +} + +impl Trait for () { + fn method(&self) -> impl Sized {} +} + +struct Struct(T); + +// This test used to fail a debug assertion since we weren't resolving the item +// for `T::method(..)` correctly, leading to two bound vars being given the +// index 0. The solution is to look at both generics of `test` and its parent impl. + +impl Struct +where + T: Trait, +{ + fn test() + where + T::method(..): Send + {} +} + +fn main() { + Struct::<()>::test(); +}