Apply suggestions, squash before merging

Author: mu001999

compiler/rustc_passes/src/dead.rs

@@ -45,15 +45,15 @@ fn should_explore(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     )
 }
 
-/// Returns the local def id and def kind of the adt,
-/// if the given ty refers to one local adt definition.
-fn local_adt_def_of_ty<'tcx>(ty: &hir::Ty<'tcx>) -> Option<(LocalDefId, DefKind)> {
+/// Returns the local def id of the ADT if the given ty refers to a local one.
+fn local_adt_def_of_ty<'tcx>(ty: &hir::Ty<'tcx>) -> Option<LocalDefId> {
     match ty.kind {
         TyKind::Path(QPath::Resolved(_, path)) => {
             if let Res::Def(def_kind, def_id) = path.res
                 && let Some(local_def_id) = def_id.as_local()
+                && matches!(def_kind, DefKind::Struct | DefKind::Enum | DefKind::Union)
             {
-                Some((local_def_id, def_kind))
+                Some(local_def_id)
             } else {
                 None
             }
@@ -485,7 +485,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
         }
     }
 
-    /// Returns whether `local_def_id` is live or not.
+    /// Returns whether `local_def_id` is potentially alive or not.
     /// `local_def_id` points to an impl or an impl item,
     /// both impl and impl item that may be passed to this function are of a trait,
     /// and added into the unsolved_items during `create_and_seed_worklist`
@@ -518,8 +518,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
 
             // FIXME: legacy logic to check whether the function may construct `Self`,
             // this can be removed after supporting marking ADTs appearing in patterns
-            // as live, then we can check private impls of.
-            // public traits directly
+            // as live, then we can check private impls of public traits directly
             if let Some(fn_sig) =
                 self.tcx.hir_fn_sig_by_hir_id(self.tcx.local_def_id_to_hir_id(local_def_id))
                 && matches!(fn_sig.decl.implicit_self, hir::ImplicitSelfKind::None)
@@ -529,10 +528,9 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
             }
         }
 
-        // The impl/impl item is used if the trait/trait item is used and the ty is used.
-        if let Some((local_def_id, def_kind)) =
+        // The impl or impl item is used if the corresponding trait or trait item is used and the ty is used.
+        if let Some(local_def_id) =
             local_adt_def_of_ty(self.tcx.hir_item(impl_id).expect_impl().self_ty)
-            && matches!(def_kind, DefKind::Struct | DefKind::Enum | DefKind::Union)
             && !self.live_symbols.contains(&local_def_id)
         {
             return false;
@@ -761,7 +759,6 @@ fn check_item<'tcx>(
                 unsolved_items.push((id, id.owner_id.def_id));
             }
 
-            // We access the Map here to get HirId from LocalDefId
             for def_id in tcx.associated_item_def_ids(id.owner_id) {
                 let local_def_id = def_id.expect_local();
 
@@ -774,11 +771,11 @@ fn check_item<'tcx>(
                     if !matches!(tcx.def_kind(local_def_id), DefKind::AssocFn) {
                         worklist.push((local_def_id, ComesFromAllowExpect::No));
                     } else {
-                        // We only care about assoc items of trait,
-                        // because they cannot be visited directly
-                        // so we mark them based on the trait/trait item
-                        // and self ty are checked first and both live,
-                        // but inherent assoc items can be visited and marked directly.
+                        // We only care about associated items of traits,
+                        // because they cannot be visited directly,
+                        // so we later mark them as live if their corresponding traits
+                        // or trait items and self types are both live,
+                        // but inherent associated items can be visited and marked directly.
                         unsolved_items.push((id, local_def_id));
                     }
                 }