From 7636f71f424abdc8d162e6e35b98358e950d40b3 Mon Sep 17 00:00:00 2001
From: Jinbo Wang <jinbwan@microsoft.com>
Date: Thu, 5 Sep 2024 16:26:08 +0800
Subject: [PATCH] Use variable kind to check if it qualifies for unused checker

---
 .../internal/javac/UnusedProblemFactory.java  | 19 ++++++++----------
 .../jdt/internal/javac/UnusedTreeScanner.java | 20 ++++++-------------
 2 files changed, 14 insertions(+), 25 deletions(-)

diff --git a/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedProblemFactory.java b/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedProblemFactory.java
index ecf57ad0e70..4a0c1a1bbb8 100644
--- a/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedProblemFactory.java
+++ b/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedProblemFactory.java
@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 
+import javax.lang.model.element.ElementKind;
 import javax.tools.JavaFileObject;
 
 import org.eclipse.jdt.core.compiler.CategorizedProblem;
@@ -33,8 +34,6 @@
 
 import com.sun.source.tree.CompilationUnitTree;
 import com.sun.source.tree.Tree;
-import com.sun.tools.javac.code.Symbol.ClassSymbol;
-import com.sun.tools.javac.code.Symbol.MethodSymbol;
 import com.sun.tools.javac.code.Symbol.VarSymbol;
 import com.sun.tools.javac.tree.JCTree.JCClassDecl;
 import com.sun.tools.javac.tree.JCTree.JCImport;
@@ -169,22 +168,20 @@ public List<CategorizedProblem> addUnusedPrivateMembers(CompilationUnitTree unit
 				int line = (int) unit.getLineMap().getLineNumber(pos);
 				int column = (int) unit.getLineMap().getColumnNumber(pos);
 				int problemId = IProblem.LocalVariableIsNeverUsed;
-				String[] arguments = null;
 				String name = variableDecl.name.toString();
+				String[] arguments = new String[] { name };
 				VarSymbol varSymbol = variableDecl.sym;
-				if (varSymbol.owner instanceof ClassSymbol) {
+				ElementKind varKind = varSymbol == null ? null : varSymbol.getKind();
+				if (varKind == ElementKind.FIELD) {
 					problemId = IProblem.UnusedPrivateField;
 					String typeName = varSymbol.owner.name.toString();
 					arguments = new String[] {
 						typeName, name
 					};
-				} else if (varSymbol.owner instanceof MethodSymbol methodSymbol) {
-					if (methodSymbol.type != null && methodSymbol.params().indexOf(varSymbol) >= 0) {
-						problemId = IProblem.ArgumentIsNeverUsed;
-					} else {
-						problemId = IProblem.LocalVariableIsNeverUsed;
-					}
-					arguments = new String[] { name };
+				} else if (varKind == ElementKind.PARAMETER) {
+					problemId = IProblem.ArgumentIsNeverUsed;
+				} else if (varKind == ElementKind.EXCEPTION_PARAMETER) {
+					problemId = IProblem.ExceptionParameterIsNeverUsed;
 				}
 
 				int severity = this.toSeverity(problemId);
diff --git a/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedTreeScanner.java b/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedTreeScanner.java
index 79896014fd8..27ffbcf204e 100644
--- a/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedTreeScanner.java
+++ b/org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/javac/UnusedTreeScanner.java
@@ -21,8 +21,6 @@
 import java.util.Map;
 import java.util.Set;
 
-import javax.lang.model.element.ElementKind;
-
 import org.eclipse.jdt.core.compiler.CategorizedProblem;
 
 import com.sun.source.tree.ClassTree;
@@ -76,7 +74,7 @@ public R visitImport(ImportTree node, P p) {
 
 	@Override
 	public R visitClass(ClassTree node, P p) {
-		if (node instanceof JCClassDecl classDecl && this.isPrivateDeclaration(classDecl)) {
+		if (node instanceof JCClassDecl classDecl && this.isPotentialUnusedDeclaration(classDecl)) {
 			this.privateDecls.add(classDecl);
 		}
 
@@ -119,7 +117,7 @@ public R visitMemberSelect(MemberSelectTree node, P p) {
 
 	@Override
 	public R visitMethod(MethodTree node, P p) {
-		boolean isPrivateMethod = this.isPrivateDeclaration(node);
+		boolean isPrivateMethod = this.isPotentialUnusedDeclaration(node);
 		if (isPrivateMethod) {
 			this.privateDecls.add(node);
 		}
@@ -129,7 +127,7 @@ public R visitMethod(MethodTree node, P p) {
 
 	@Override
 	public R visitVariable(VariableTree node, P p) {
-		boolean isPrivateVariable = this.isPrivateDeclaration(node);
+		boolean isPrivateVariable = this.isPotentialUnusedDeclaration(node);
 		if (isPrivateVariable) {
 			this.privateDecls.add(node);
 		}
@@ -158,15 +156,13 @@ public R visitNewClass(NewClassTree node, P p) {
 		return super.visitNewClass(node, p);
 	}
 
-	private boolean isPrivateDeclaration(Tree tree) {
+	private boolean isPotentialUnusedDeclaration(Tree tree) {
 		if (tree instanceof JCClassDecl classTree) {
 			return (classTree.getModifiers().flags & Flags.PRIVATE) != 0;
 		} else if (tree instanceof JCMethodDecl methodTree) {
 			if (isConstructor(methodTree)) {
-				if (hasPackageVisibleConstructor(methodTree.sym.owner)) {
-					return (methodTree.getModifiers().flags & Flags.PRIVATE) != 0;
-				}
-				return false;
+				return (methodTree.getModifiers().flags & Flags.PRIVATE) != 0
+						&& hasPackageVisibleConstructor(methodTree.sym.owner);
 			}
 			return (methodTree.getModifiers().flags & Flags.PRIVATE) != 0;
 		} else if (tree instanceof JCVariableDecl variable) {
@@ -174,10 +170,6 @@ private boolean isPrivateDeclaration(Tree tree) {
 			if (owner instanceof ClassSymbol) {
 				return !isSerialVersionConstant(variable) && (variable.getModifiers().flags & Flags.PRIVATE) != 0;
 			} else if (owner instanceof MethodSymbol) {
-				if (variable.sym.getKind() == ElementKind.EXCEPTION_PARAMETER) {
-					return false;
-				}
-
 				return true;
 			}
 		}