diff options
Diffstat (limited to 'compiler/rustc_ty_utils/src/instance.rs')
| -rw-r--r-- | compiler/rustc_ty_utils/src/instance.rs | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/compiler/rustc_ty_utils/src/instance.rs b/compiler/rustc_ty_utils/src/instance.rs index da2958bf56e..91f1c21310e 100644 --- a/compiler/rustc_ty_utils/src/instance.rs +++ b/compiler/rustc_ty_utils/src/instance.rs @@ -141,11 +141,34 @@ fn resolve_associated_item<'tcx>( false } }; - if !eligible { return Ok(None); } + // HACK: We may have overlapping `dyn Trait` built-in impls and + // user-provided blanket impls. Detect that case here, and return + // ambiguity. + // + // This should not affect totally monomorphized contexts, only + // resolve calls that happen polymorphically, such as the mir-inliner + // and const-prop (and also some lints). + let self_ty = rcvr_args.type_at(0); + if !self_ty.is_known_rigid() { + let predicates = tcx + .predicates_of(impl_data.impl_def_id) + .instantiate(tcx, impl_data.args) + .predicates; + let sized_def_id = tcx.lang_items().sized_trait(); + // If we find a `Self: Sized` bound on the item, then we know + // that `dyn Trait` can certainly never apply here. + if !predicates.into_iter().filter_map(ty::Clause::as_trait_clause).any(|clause| { + Some(clause.def_id()) == sized_def_id + && clause.skip_binder().self_ty() == self_ty + }) { + return Ok(None); + } + } + // Any final impl is required to define all associated items. if !leaf_def.item.defaultness(tcx).has_value() { let guard = tcx.sess.delay_span_bug( |