From 28af50075724bd1fa94b7e147b1e230534a70ab9 Mon Sep 17 00:00:00 2001 From: León Orell Valerian Liehr Date: Fri, 11 Jul 2025 15:20:03 +0200 Subject: Opaque type collection: Guard against endlessly recursing free alias types --- compiler/rustc_ty_utils/src/opaque_types.rs | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'compiler/rustc_ty_utils/src') diff --git a/compiler/rustc_ty_utils/src/opaque_types.rs b/compiler/rustc_ty_utils/src/opaque_types.rs index 3b313edea6f..4a7263d0ccd 100644 --- a/compiler/rustc_ty_utils/src/opaque_types.rs +++ b/compiler/rustc_ty_utils/src/opaque_types.rs @@ -223,7 +223,10 @@ impl<'tcx> TypeVisitor> for OpaqueTypeCollector<'tcx> { } // Skips type aliases, as they are meant to be transparent. // FIXME(type_alias_impl_trait): can we require mentioning nested type aliases explicitly? - ty::Alias(ty::Free, alias_ty) if alias_ty.def_id.is_local() => { + ty::Alias(ty::Free, alias_ty) if let Some(def_id) = alias_ty.def_id.as_local() => { + if !self.seen.insert(def_id) { + return; + } self.tcx .type_of(alias_ty.def_id) .instantiate(self.tcx, alias_ty.args) @@ -256,16 +259,16 @@ impl<'tcx> TypeVisitor> for OpaqueTypeCollector<'tcx> { return; } - let impl_args = alias_ty.args.rebase_onto( + let alias_args = alias_ty.args.rebase_onto( self.tcx, impl_trait_ref.def_id, ty::GenericArgs::identity_for_item(self.tcx, parent), ); - if self.tcx.check_args_compatible(assoc.def_id, impl_args) { + if self.tcx.check_args_compatible(assoc.def_id, alias_args) { self.tcx .type_of(assoc.def_id) - .instantiate(self.tcx, impl_args) + .instantiate(self.tcx, alias_args) .visit_with(self); return; } else { -- cgit 1.4.1-3-g733a5