Only walk local items instead of filtering for them later

Author: oli-obk

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -1730,25 +1730,23 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         .is_accessible_from(self.item_def_id(), tcx)
                     && tcx.all_impls(*trait_def_id)
                         .any(|impl_def_id| {
-                            let impl_header = tcx.impl_trait_header(impl_def_id);
-                            impl_header.is_some_and(|header| {
-                                let trait_ref = header.trait_ref.instantiate(
-                                    tcx,
-                                    infcx.fresh_args_for_item(DUMMY_SP, impl_def_id),
-                                );
-
-                                let value = fold_regions(tcx, qself_ty, |_, _| tcx.lifetimes.re_erased);
-                                // FIXME: Don't bother dealing with non-lifetime binders here...
-                                if value.has_escaping_bound_vars() {
-                                    return false;
-                                }
-                                infcx
-                                    .can_eq(
-                                        ty::ParamEnv::empty(),
-                                        trait_ref.self_ty(),
-                                        value,
-                                    ) && header.polarity != ty::ImplPolarity::Negative
-                            })
+                            let header = tcx.impl_trait_header(impl_def_id).unwrap();
+                            let trait_ref = header.trait_ref.instantiate(
+                                tcx,
+                                infcx.fresh_args_for_item(DUMMY_SP, impl_def_id),
+                            );
+
+                            let value = fold_regions(tcx, qself_ty, |_, _| tcx.lifetimes.re_erased);
+                            // FIXME: Don't bother dealing with non-lifetime binders here...
+                            if value.has_escaping_bound_vars() {
+                                return false;
+                            }
+                            infcx
+                                .can_eq(
+                                    ty::ParamEnv::empty(),
+                                    trait_ref.self_ty(),
+                                    value,
+                                ) && header.polarity != ty::ImplPolarity::Negative
                         })
             })
             .map(|trait_def_id| tcx.def_path_str(trait_def_id))

compiler/rustc_passes/src/dead.rs

@@ -421,10 +421,8 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
                 }
                 hir::ItemKind::ForeignMod { .. } => {}
                 hir::ItemKind::Trait(..) => {
-                    for impl_def_id in self.tcx.all_impls(item.owner_id.to_def_id()) {
-                        if let Some(local_def_id) = impl_def_id.as_local()
-                            && let ItemKind::Impl(impl_ref) =
-                                self.tcx.hir_expect_item(local_def_id).kind
+                    for &impl_def_id in self.tcx.local_trait_impls(item.owner_id.def_id) {
+                        if let ItemKind::Impl(impl_ref) = self.tcx.hir_expect_item(impl_def_id).kind
                         {
                             // skip items
                             // mark dependent traits live