rustc: Parameterize ty::Visibility over used ID

It allows using `LocalDefId` instead of `DefId` when possible, and also encode cheaper `Visibility<DefIndex>` into metadata.

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -911,8 +911,14 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         self.root.tables.generics_of.get(self, item_id).unwrap().decode((self, sess))
     }
 
-    fn get_visibility(self, id: DefIndex) -> ty::Visibility {
-        self.root.tables.visibility.get(self, id).unwrap().decode(self)
+    fn get_visibility(self, id: DefIndex) -> ty::Visibility<DefId> {
+        self.root
+            .tables
+            .visibility
+            .get(self, id)
+            .unwrap()
+            .decode(self)
+            .map_id(|index| self.local_def_id(index))
     }
 
     fn get_trait_item_def_id(self, id: DefIndex) -> Option<DefId> {
@@ -1182,7 +1188,10 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
             .map(move |index| respan(self.get_span(index, sess), self.item_name(index)))
     }
 
-    fn get_struct_field_visibilities(self, id: DefIndex) -> impl Iterator<Item = Visibility> + 'a {
+    fn get_struct_field_visibilities(
+        self,
+        id: DefIndex,
+    ) -> impl Iterator<Item = Visibility<DefId>> + 'a {
         self.root
             .tables
             .children

compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs

@@ -210,7 +210,6 @@ provide! { tcx, def_id, other, cdata,
     lookup_const_stability => { table }
     lookup_default_body_stability => { table }
     lookup_deprecation_entry => { table }
-    visibility => { table }
     unused_generic_params => { table }
     opt_def_kind => { table_direct }
     impl_parent => { table }
@@ -225,6 +224,7 @@ provide! { tcx, def_id, other, cdata,
     generator_kind => { table }
     trait_def => { table }
 
+    visibility => { cdata.get_visibility(def_id.index) }
     adt_def => { cdata.get_adt_def(def_id.index, tcx) }
     adt_destructor => {
         let _ = cdata;
@@ -485,7 +485,7 @@ impl CStore {
     pub fn struct_field_visibilities_untracked(
         &self,
         def: DefId,
-    ) -> impl Iterator<Item = Visibility> + '_ {
+    ) -> impl Iterator<Item = Visibility<DefId>> + '_ {
         self.get_crate_data(def.krate).get_struct_field_visibilities(def.index)
     }
 
@@ -493,7 +493,7 @@ impl CStore {
         self.get_crate_data(def.krate).get_ctor_def_id_and_kind(def.index)
     }
 
-    pub fn visibility_untracked(&self, def: DefId) -> Visibility {
+    pub fn visibility_untracked(&self, def: DefId) -> Visibility<DefId> {
         self.get_crate_data(def.krate).get_visibility(def.index)
     }
 

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1138,7 +1138,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 record!(self.tables.codegen_fn_attrs[def_id] <- self.tcx.codegen_fn_attrs(def_id));
             }
             if should_encode_visibility(def_kind) {
-                record!(self.tables.visibility[def_id] <- self.tcx.visibility(def_id));
+                let vis =
+                    self.tcx.local_visibility(local_id).map_id(|def_id| def_id.local_def_index);
+                record!(self.tables.visibility[def_id] <- vis);
             }
             if should_encode_stability(def_kind) {
                 self.encode_stability(def_id);
@@ -1727,7 +1729,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             self.tables.opt_def_kind.set(LOCAL_CRATE.as_def_id().index, DefKind::Mod);
             record!(self.tables.def_span[LOCAL_CRATE.as_def_id()] <- tcx.def_span(LOCAL_CRATE.as_def_id()));
             self.encode_attrs(LOCAL_CRATE.as_def_id().expect_local());
-            record!(self.tables.visibility[LOCAL_CRATE.as_def_id()] <- tcx.visibility(LOCAL_CRATE.as_def_id()));
+            let vis = tcx.local_visibility(CRATE_DEF_ID).map_id(|def_id| def_id.local_def_index);
+            record!(self.tables.visibility[LOCAL_CRATE.as_def_id()] <- vis);
             if let Some(stability) = stability {
                 record!(self.tables.lookup_stability[LOCAL_CRATE.as_def_id()] <- stability);
             }

compiler/rustc_metadata/src/rmeta/mod.rs

@@ -338,7 +338,7 @@ define_tables! {
     children: Table<DefIndex, LazyArray<DefIndex>>,
 
     opt_def_kind: Table<DefIndex, DefKind>,
-    visibility: Table<DefIndex, LazyValue<ty::Visibility>>,
+    visibility: Table<DefIndex, LazyValue<ty::Visibility<DefIndex>>>,
     def_span: Table<DefIndex, LazyValue<Span>>,
     def_ident_span: Table<DefIndex, LazyValue<Span>>,
     lookup_stability: Table<DefIndex, LazyValue<attr::Stability>>,