diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs index 4ce401b52bd..0cf58179ec2 100644 --- a/compiler/rustc_hir_typeck/src/method/probe.rs +++ b/compiler/rustc_hir_typeck/src/method/probe.rs @@ -951,24 +951,38 @@ fn assemble_extension_candidates_for_trait( let trait_ref = self.tcx.mk_trait_ref(trait_def_id, trait_substs); if self.tcx.is_trait_alias(trait_def_id) { - // For trait aliases, assume all supertraits are relevant. - let bounds = iter::once(ty::Binder::dummy(trait_ref)); - self.elaborate_bounds(bounds, |this, new_trait_ref, item| { - let new_trait_ref = this.erase_late_bound_regions(new_trait_ref); + // For trait aliases, recursively assume all explicitly named traits are relevant + for expansion in traits::expand_trait_aliases( + self.tcx, + iter::once((ty::Binder::dummy(trait_ref), self.span)), + ) { + let bound_trait_ref = expansion.trait_ref(); + for item in self.impl_or_trait_item(bound_trait_ref.def_id()) { + if !self.has_applicable_self(&item) { + self.record_static_candidate(CandidateSource::Trait( + bound_trait_ref.def_id(), + )); + } else { + let new_trait_ref = self.erase_late_bound_regions(bound_trait_ref); - let (xform_self_ty, xform_ret_ty) = - this.xform_self_ty(&item, new_trait_ref.self_ty(), new_trait_ref.substs); - this.push_candidate( - Candidate { - xform_self_ty, - xform_ret_ty, - item, - import_ids: import_ids.clone(), - kind: TraitCandidate(new_trait_ref), - }, - false, - ); - }); + let (xform_self_ty, xform_ret_ty) = self.xform_self_ty( + &item, + new_trait_ref.self_ty(), + new_trait_ref.substs, + ); + self.push_candidate( + Candidate { + xform_self_ty, + xform_ret_ty, + item, + import_ids: import_ids.clone(), + kind: TraitCandidate(new_trait_ref), + }, + false, + ); + } + } + } } else { debug_assert!(self.tcx.is_trait(trait_def_id)); if self.tcx.trait_is_auto(trait_def_id) { diff --git a/tests/ui/traits/alias/issue-107747-do-not-assemble-supertraits.rs b/tests/ui/traits/alias/issue-107747-do-not-assemble-supertraits.rs new file mode 100644 index 00000000000..9b41a8096c4 --- /dev/null +++ b/tests/ui/traits/alias/issue-107747-do-not-assemble-supertraits.rs @@ -0,0 +1,21 @@ +// Regression test for #107747: methods from trait alias supertraits were brought into scope +// +// check-pass + +#![feature(trait_alias)] + +use std::fmt; + +trait Foo: fmt::Debug {} +trait Bar = Foo; + +#[derive(Debug)] +struct Qux(bool); + +impl fmt::Display for Qux { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + self.0.fmt(f) + } +} + +fn main() {}