Don't store defaultness for inherent impl items

Author: camsteffen

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1725,11 +1725,11 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         let tcx = self.tcx;
         let item = tcx.associated_item(def_id);
 
-        self.tables.defaultness.set_some(def_id.index, item.defaultness(tcx));
         self.tables.assoc_container.set_some(def_id.index, item.container);
 
         match item.container {
             AssocItemContainer::Trait => {
+                self.tables.defaultness.set_some(def_id.index, item.defaultness(tcx));
                 if item.is_type() {
                     self.encode_explicit_item_bounds(def_id);
                     self.encode_explicit_item_self_bounds(def_id);
@@ -1740,6 +1740,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 }
             }
             AssocItemContainer::TraitImpl => {
+                self.tables.defaultness.set_some(def_id.index, item.defaultness(tcx));
                 if let Some(trait_item_def_id) = item.trait_item_def_id {
                     self.tables.trait_item_def_id.set_some(def_id.index, trait_item_def_id.into());
                 }

compiler/rustc_middle/src/ty/assoc.rs

@@ -57,7 +57,12 @@ impl AssocItem {
     ///
     /// [`type_of`]: crate::ty::TyCtxt::type_of
     pub fn defaultness(&self, tcx: TyCtxt<'_>) -> hir::Defaultness {
-        tcx.defaultness(self.def_id)
+        match self.container {
+            AssocItemContainer::InherentImpl => hir::Defaultness::Final,
+            AssocItemContainer::Trait | AssocItemContainer::TraitImpl => {
+                tcx.defaultness(self.def_id)
+            }
+        }
     }
 
     #[inline]

compiler/rustc_ty_utils/src/ty.rs

@@ -89,10 +89,6 @@ fn defaultness(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::Defaultness {
             ..
         })
         | hir::Node::TraitItem(hir::TraitItem { defaultness, .. }) => *defaultness,
-        hir::Node::ImplItem(hir::ImplItem {
-            impl_kind: hir::ImplItemImplKind::Inherent { .. },
-            ..
-        }) => hir::Defaultness::Final,
         node => {
             bug!("`defaultness` called on {:?}", node);
         }