Stop tracking namespce in used_imports.

The information was tracked, but unused.

compiler/rustc_resolve/src/check_unused.rs

@@ -63,8 +63,7 @@ impl<'a, 'b> UnusedImportCheckVisitor<'a, 'b> {
     // We have information about whether `use` (import) items are actually
     // used now. If an import is not used at all, we signal a lint error.
     fn check_import(&mut self, id: ast::NodeId) {
-        let mut used = false;
+        let used = self.r.used_imports.contains(&id);
-        self.r.per_ns(|this, ns| used |= this.used_imports.contains(&(id, ns)));
         let def_id = self.r.local_def_id(id);
         if !used {
             if self.r.maybe_unused_trait_imports.contains(&def_id) {

compiler/rustc_resolve/src/imports.rs

@@ -303,7 +303,7 @@ impl<'a> Resolver<'a> {
                     if self.last_import_segment && check_usable(self, binding).is_err() {
                         Err((Determined, Weak::No))
                     } else {
-                        self.record_use(ident, ns, binding, restricted_shadowing);
+                        self.record_use(ident, binding, restricted_shadowing);
 
                         if let Some(shadowed_glob) = resolution.shadowed_glob {
                             // Forbid expanded shadowing to avoid time travel.
@@ -609,9 +609,9 @@ impl<'a> Resolver<'a> {
             self.per_ns(|this, ns| {
                 let key = this.new_key(target, ns);
                 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
-                // Consider erroneous imports used to avoid duplicate diagnostics.
-                this.record_use(target, ns, dummy_binding, false);
             });
+            // Consider erroneous imports used to avoid duplicate diagnostics.
+            self.record_use(target, dummy_binding, false);
         }
     }
 }
@@ -709,7 +709,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                 }
             } else if is_indeterminate {
                 // Consider erroneous imports used to avoid duplicate diagnostics.
-                self.r.used_imports.insert((import.id, TypeNS));
+                self.r.used_imports.insert(import.id);
                 let path = import_path_to_string(
                     &import.module_path.iter().map(|seg| seg.ident).collect::<Vec<_>>(),
                     &import.kind,
@@ -902,7 +902,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
         import.vis.set(orig_vis);
         if let PathResult::Failed { .. } | PathResult::NonModule(..) = path_res {
             // Consider erroneous imports used to avoid duplicate diagnostics.
-            self.r.used_imports.insert((import.id, TypeNS));
+            self.r.used_imports.insert(import.id);
         }
         let module = match path_res {
             PathResult::Module(module) => {
@@ -1043,7 +1043,6 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                                 {
                                     this.record_use(
                                         ident,
-                                        ns,
                                         target_binding,
                                         import.module_path.is_empty(),
                                     );

compiler/rustc_resolve/src/late.rs

@@ -1738,7 +1738,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 // whether they can be shadowed by fresh bindings or not, so force an error.
                 // issues/33118#issuecomment-233962221 (see below) still applies here,
                 // but we have to ignore it for backward compatibility.
-                self.r.record_use(ident, ValueNS, binding, false);
+                self.r.record_use(ident, binding, false);
                 return None;
             }
             LexicalScopeBinding::Item(binding) => (binding.res(), Some(binding)),
@@ -1753,7 +1753,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
             ) if is_syntactic_ambiguity => {
                 // Disambiguate in favor of a unit struct/variant or constant pattern.
                 if let Some(binding) = binding {
-                    self.r.record_use(ident, ValueNS, binding, false);
+                    self.r.record_use(ident, binding, false);
                 }
                 Some(res)
             }

compiler/rustc_resolve/src/lib.rs

@@ -942,7 +942,7 @@ pub struct Resolver<'a> {
     glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
     /// Visibilities in "lowered" form, for all entities that have them.
     visibilities: FxHashMap<LocalDefId, ty::Visibility>,
-    used_imports: FxHashSet<(NodeId, Namespace)>,
+    used_imports: FxHashSet<NodeId>,
     maybe_unused_trait_imports: FxHashSet<LocalDefId>,
     maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
 
@@ -1656,7 +1656,6 @@ impl<'a> Resolver<'a> {
     fn record_use(
         &mut self,
         ident: Ident,
-        ns: Namespace,
         used_binding: &'a NameBinding<'a>,
         is_lexical_scope: bool,
     ) {
@@ -1684,9 +1683,9 @@ impl<'a> Resolver<'a> {
             }
             used.set(true);
             import.used.set(true);
-            self.used_imports.insert((import.id, ns));
+            self.used_imports.insert(import.id);
             self.add_to_glob_map(&import, ident);
-            self.record_use(ident, ns, binding, false);
+            self.record_use(ident, binding, false);
         }
     }
 
@@ -3241,7 +3240,7 @@ impl<'a> Resolver<'a> {
         self.extern_prelude.get(&ident.normalize_to_macros_2_0()).cloned().and_then(|entry| {
             if let Some(binding) = entry.extern_crate_item {
                 if !speculative && entry.introduced_by_item {
-                    self.record_use(ident, TypeNS, binding, false);
+                    self.record_use(ident, binding, false);
                 }
                 Some(binding)
             } else {
@@ -3428,7 +3427,7 @@ impl<'a> Resolver<'a> {
         let is_import = name_binding.is_import();
         let span = name_binding.span;
         if let Res::Def(DefKind::Fn, _) = res {
-            self.record_use(ident, ValueNS, name_binding, false);
+            self.record_use(ident, name_binding, false);
         }
         self.main_def = Some(MainDefinition { res, is_import, span });
     }

compiler/rustc_resolve/src/macros.rs

@@ -1090,7 +1090,7 @@ impl<'a> Resolver<'a> {
             ) {
                 Ok(binding) => {
                     let initial_res = initial_binding.map(|initial_binding| {
-                        self.record_use(ident, MacroNS, initial_binding, false);
+                        self.record_use(ident, initial_binding, false);
                         initial_binding.res()
                     });
                     let res = binding.res();