Trait impls are Items, therefore HIR owners.

compiler/rustc_ast_lowering/src/item.rs

@@ -396,8 +396,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 self_ty: ref ty,
                 items: ref impl_items,
             }) => {
-                let def_id = self.resolver.local_def_id(id);
-
                 // Lower the "impl header" first. This ordering is important
                 // for in-band lifetimes! Consider `'a` here:
                 //
@@ -411,10 +409,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // method, it will not be considered an in-band
                 // lifetime to be added, but rather a reference to a
                 // parent lifetime.
-                let lowered_trait_impl_id = self.lower_node_id(id);
+                let lowered_trait_def_id = self.lower_node_id(id).expect_owner();
                 let (generics, (trait_ref, lowered_ty)) = self.add_in_band_defs(
                     ast_generics,
-                    def_id,
+                    lowered_trait_def_id,
                     AnonymousLifetimeMode::CreateParameter,
                     |this, _| {
                         let trait_ref = trait_ref.as_ref().map(|trait_ref| {
@@ -426,7 +424,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                                 this.trait_impls
                                     .entry(def_id)
                                     .or_default()
-                                    .push(lowered_trait_impl_id);
+                                    .push(lowered_trait_def_id);
                             }
                         }
 

compiler/rustc_ast_lowering/src/lib.rs

@@ -108,7 +108,7 @@ struct LoweringContext<'a, 'hir: 'a> {
     exported_macros: Vec<hir::MacroDef<'hir>>,
     non_exported_macro_attrs: Vec<ast::Attribute>,
 
-    trait_impls: BTreeMap<DefId, Vec<hir::HirId>>,
+    trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
 
     modules: BTreeMap<LocalDefId, hir::ModuleItems>,
 

compiler/rustc_hir/src/hir.rs

@@ -658,7 +658,7 @@ pub struct Crate<'hir> {
     pub impl_items: BTreeMap<ImplItemId, ImplItem<'hir>>,
     pub foreign_items: BTreeMap<ForeignItemId, ForeignItem<'hir>>,
     pub bodies: BTreeMap<BodyId, Body<'hir>>,
-    pub trait_impls: BTreeMap<DefId, Vec<HirId>>,
+    pub trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
 
     /// A list of the body ids written out in the order in which they
     /// appear in the crate. If you're going to process all the bodies

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs

@@ -361,8 +361,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             .hir()
                             .trait_impls(trait_did)
                             .iter()
-                            .filter_map(|impl_node| {
+                            .filter_map(|&impl_did| {
-                                let impl_did = tcx.hir().local_def_id(*impl_node);
                                 match tcx.hir().get_if_local(impl_did.to_def_id()) {
                                     Some(Node::Item(Item {
                                         kind: ItemKind::Impl(hir::Impl { self_ty, .. }),

compiler/rustc_middle/src/hir/map/mod.rs

@@ -449,7 +449,7 @@ impl<'hir> Map<'hir> {
         }
     }
 
-    pub fn trait_impls(&self, trait_did: DefId) -> &'hir [HirId] {
+    pub fn trait_impls(&self, trait_did: DefId) -> &'hir [LocalDefId] {
         self.tcx.all_local_trait_impls(LOCAL_CRATE).get(&trait_did).map_or(&[], |xs| &xs[..])
     }
 

compiler/rustc_middle/src/query/mod.rs

@@ -956,7 +956,7 @@ rustc_queries! {
     /// Passing in any other crate will cause an ICE.
     ///
     /// [`LOCAL_CRATE`]: rustc_hir::def_id::LOCAL_CRATE
-    query all_local_trait_impls(local_crate: CrateNum) -> &'tcx BTreeMap<DefId, Vec<hir::HirId>> {
+    query all_local_trait_impls(local_crate: CrateNum) -> &'tcx BTreeMap<DefId, Vec<LocalDefId>> {
         desc { "local trait impls" }
     }
 

compiler/rustc_middle/src/ty/trait_def.rs

@@ -4,9 +4,8 @@ use crate::ty::fast_reject;
 use crate::ty::fold::TypeFoldable;
 use crate::ty::{Ty, TyCtxt};
 use rustc_hir as hir;
-use rustc_hir::def_id::{CrateNum, DefId};
+use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
 use rustc_hir::definitions::DefPathHash;
-use rustc_hir::HirId;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -201,7 +200,7 @@ impl<'tcx> TyCtxt<'tcx> {
 pub(super) fn all_local_trait_impls<'tcx>(
     tcx: TyCtxt<'tcx>,
     krate: CrateNum,
-) -> &'tcx BTreeMap<DefId, Vec<HirId>> {
+) -> &'tcx BTreeMap<DefId, Vec<LocalDefId>> {
     &tcx.hir_crate(krate).trait_impls
 }
 
@@ -229,8 +228,8 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
         }
     }
 
-    for &hir_id in tcx.hir().trait_impls(trait_id) {
+    for &impl_def_id in tcx.hir().trait_impls(trait_id) {
-        let impl_def_id = tcx.hir().local_def_id(hir_id).to_def_id();
+        let impl_def_id = impl_def_id.to_def_id();
 
         let impl_self_ty = tcx.type_of(impl_def_id);
         if impl_self_ty.references_error() {

compiler/rustc_typeck/src/coherence/builtin.rs

@@ -38,8 +38,7 @@ impl<'tcx> Checker<'tcx> {
         F: FnMut(TyCtxt<'tcx>, LocalDefId),
     {
         if Some(self.trait_def_id) == trait_def_id {
-            for &impl_id in self.tcx.hir().trait_impls(self.trait_def_id) {
+            for &impl_def_id in self.tcx.hir().trait_impls(self.trait_def_id) {
-                let impl_def_id = self.tcx.hir().local_def_id(impl_id);
                 f(self.tcx, impl_def_id);
             }
         }

compiler/rustc_typeck/src/coherence/mod.rs

@@ -172,8 +172,7 @@ fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) {
     tcx.ensure().specialization_graph_of(def_id);
 
     let impls = tcx.hir().trait_impls(def_id);
-    for &hir_id in impls {
+    for &impl_def_id in impls {
-        let impl_def_id = tcx.hir().local_def_id(hir_id);
         let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
 
         check_impl(tcx, impl_def_id, trait_ref);

src/librustdoc/passes/collect_trait_impls.rs

@@ -58,8 +58,8 @@ crate fn collect_trait_impls(krate: Crate, cx: &DocContext<'_>) -> Crate {
     // doesn't work with it anyway, so pull them from the HIR map instead
     let mut extra_attrs = Vec::new();
     for &trait_did in cx.tcx.all_traits(LOCAL_CRATE).iter() {
-        for &impl_node in cx.tcx.hir().trait_impls(trait_did) {
+        for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
-            let impl_did = cx.tcx.hir().local_def_id(impl_node).to_def_id();
+            let impl_did = impl_did.to_def_id();
             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {
                 let mut parent = cx.tcx.parent(impl_did);
                 while let Some(did) = parent {