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,