Avoid storing the LocalDefId twice

Author: oli-obk

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -1209,7 +1209,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                     .unused_macro_rules
                     .entry(node_id)
                     .or_default()
-                    .insert(*rule_i, (ident, *rule_span, def_id));
+                    .insert(*rule_i, (ident, *rule_span));
             }
         }
     }

compiler/rustc_resolve/src/lib.rs

@@ -1140,7 +1140,7 @@ pub struct Resolver<'ra, 'tcx> {
     ast_transform_scopes: FxHashMap<LocalExpnId, Module<'ra>>,
     unused_macros: FxIndexMap<LocalDefId, (NodeId, Ident)>,
     /// A map from the macro to all its potentially unused arms.
-    unused_macro_rules: FxIndexMap<NodeId, UnordMap<usize, (Ident, Span, LocalDefId)>>,
+    unused_macro_rules: FxIndexMap<NodeId, UnordMap<usize, (Ident, Span)>>,
     proc_macro_stubs: FxHashSet<LocalDefId>,
     /// Traces collected during macro resolution and validated when it's complete.
     single_segment_macro_resolutions:

compiler/rustc_resolve/src/macros.rs

@@ -336,14 +336,12 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
                 ident.span,
                 BuiltinLintDiag::UnusedMacroDefinition(ident.name),
             );
+            // Do not report unused individual rules if the entire macro is unused
+            self.unused_macro_rules.swap_remove(&node_id);
         }
 
         for (&node_id, unused_arms) in self.unused_macro_rules.iter() {
-            for (&arm_i, &(ident, rule_span, def_id)) in unused_arms.to_sorted_stable_ord() {
-                if self.unused_macros.contains_key(&def_id) {
-                    // We already lint the entire macro as unused
-                    continue;
-                }
+            for (&arm_i, &(ident, rule_span)) in unused_arms.to_sorted_stable_ord() {
                 self.lint_buffer.buffer_lint(
                     UNUSED_MACRO_RULES,
                     node_id,