Clean up unused function parameters and unnecessary Map<T, T> that could be a Set<T>

PiperOrigin-RevId: 704413159

Author: lauraharker

src/com/google/javascript/jscomp/StripCode.java

@@ -22,7 +22,7 @@
 
 import com.google.common.collect.ImmutableSet;
 import com.google.javascript.jscomp.CodingConvention.SubclassRelationship;
-import com.google.javascript.jscomp.base.LinkedIdentityHashMap;
+import com.google.javascript.jscomp.base.LinkedIdentityHashSet;
 import com.google.javascript.jscomp.diagnostic.LogFile;
 import com.google.javascript.rhino.IR;
 import com.google.javascript.rhino.Node;
@@ -54,7 +54,7 @@ class StripCode implements CompilerPass {
   private final AbstractCompiler compiler;
   private final ImmutableSet<String> stripNameSuffixes;
   private final ImmutableSet<String> stripNamePrefixes;
-  private final LinkedIdentityHashMap<String, String> varsToRemove = new LinkedIdentityHashMap<>();
+  private final LinkedIdentityHashSet<String> varsToRemove = new LinkedIdentityHashSet<>();
 
   private final String[] stripTypesList;
   private final String[] stripTypePrefixesList;
@@ -246,7 +246,7 @@ public void visit(NodeTraversal t, Node n, Node parent) {
           break;
 
         case OBJECTLIT:
-          eliminateKeysWithStripNamesFromObjLit(t, n);
+          eliminateKeysWithStripNamesFromObjLit(n);
           break;
 
         case EXPR_RESULT:
@@ -288,7 +288,7 @@ void removeVarDeclarationsByNameOrRvalue(NodeTraversal t, Node n, Node parent) {
             || qualifiedNameBeginsWithStripType(nameNode)
             || isCallWhoseReturnValueShouldBeStripped(nameNode.getFirstChild())) {
           // Remove the NAME.
-          varsToRemove.put(name, name);
+          varsToRemove.add(name);
           if (name.contains("$")) {
             // We need to be careful with this code pattern that appears after
             // collapsing properties.
@@ -353,7 +353,7 @@ void maybeRemoveReferenceToRemovedVariable(NodeTraversal t, Node n, Node parent)
           // GETELEM
           //   NAME
           //   NUMBER|STRING|NAME|...
-          if (parent.getFirstChild() == n && isReferenceToRemovedVar(t, n)) {
+          if (parent.getFirstChild() == n && isReferenceToRemovedVar(n)) {
             decisionsLog.log(() -> n.getString() + ": removing getelem/getprop/call chain");
             replaceHighestNestedCallWithNull(t, parent, parent.getParent());
           }
@@ -371,7 +371,7 @@ void maybeRemoveReferenceToRemovedVariable(NodeTraversal t, Node n, Node parent)
         case ASSIGN_MUL:
         case ASSIGN_DIV:
         case ASSIGN_MOD:
-          if (isReferenceToRemovedVar(t, n)) {
+          if (isReferenceToRemovedVar(n)) {
             if (parent.getFirstChild() == n) {
               Node grandparent = parent.getParent();
               decisionsLog.log(
@@ -399,7 +399,7 @@ void maybeRemoveReferenceToRemovedVariable(NodeTraversal t, Node n, Node parent)
 
         case NEW:
         case CALL:
-          if (!n.isFirstChildOf(parent) && isReferenceToRemovedVar(t, n)) {
+          if (!n.isFirstChildOf(parent) && isReferenceToRemovedVar(n)) {
             // NOTE: the callee is handled when we visit the CALL or NEW node
             decisionsLog.log(
                 () -> n.getQualifiedName() + ": replacing parameter reference with null");
@@ -419,7 +419,7 @@ void maybeRemoveReferenceToRemovedVariable(NodeTraversal t, Node n, Node parent)
           boolean parentIsCallee =
               (grandparent.isCall() || grandparent.isNew()) && parent.isFirstChildOf(grandparent);
           boolean isSafeToRemove = !isLastChild || !parentIsCallee;
-          if (isSafeToRemove && isReferenceToRemovedVar(t, n)) {
+          if (isSafeToRemove && isReferenceToRemovedVar(n)) {
             decisionsLog.log(
                 () -> n.getQualifiedName() + ": replacing reference in comma expr with null");
             replaceWithNull(n);
@@ -428,7 +428,7 @@ void maybeRemoveReferenceToRemovedVariable(NodeTraversal t, Node n, Node parent)
           break;
 
         default:
-          if (isReferenceToRemovedVar(t, n)) {
+          if (isReferenceToRemovedVar(n)) {
             decisionsLog.log(() -> n.getQualifiedName() + ": replacing reference with null");
             replaceWithNull(n);
             t.reportCodeChange();
@@ -550,10 +550,9 @@ void maybeEliminateExpressionByName(Node n) {
     /**
      * Eliminates any object literal keys in an object literal declaration that have strip names.
      *
-     * @param t The traversal
      * @param n An OBJLIT node
      */
-    void eliminateKeysWithStripNamesFromObjLit(NodeTraversal t, Node n) {
+    void eliminateKeysWithStripNamesFromObjLit(Node n) {
       // OBJLIT
       //   key1
       //     value1
@@ -680,12 +679,11 @@ boolean qualifiedNameBeginsWithStripType(String name) {
     /**
      * Determines whether a NAME node represents a reference to a variable that has been removed.
      *
-     * @param t The traversal
      * @param n A NAME node
      * @return Whether the variable was removed
      */
-    boolean isReferenceToRemovedVar(NodeTraversal t, Node n) {
-      return varsToRemove.get(n.getString()) != null;
+    boolean isReferenceToRemovedVar(Node n) {
+      return varsToRemove.contains(n.getString());
     }
 
     /**
@@ -695,7 +693,7 @@ boolean isReferenceToRemovedVar(NodeTraversal t, Node n) {
      * class-defining functions (e.g. goog.inherits).
      *
      * @param t The traversal
-     * @param n A CALL node
+     * @param n A CALL or NEW node
      * @return Whether the node triggers statement removal
      */
     boolean isMethodOrCtorCallThatTriggersRemoval(NodeTraversal t, Node n, Node parent) {