[java-inspections] IDEA-341640 Mark main(String[] args) parameter as unused with implicit classes

GitOrigin-RevId: 08ca1f5ed4f48439b394f7fd313f2b95d50c48e7

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/PostHighlightingVisitor.java

@@ -379,7 +379,7 @@ class PostHighlightingVisitor extends JavaElementVisitor {
            (!isOverriddenOrOverrides(method) || myUnusedSymbolInspection.checkParameterExcludingHierarchy())) &&
           !method.hasModifierProperty(PsiModifier.NATIVE) &&
           !JavaHighlightUtil.isSerializationRelatedMethod(method, method.getContainingClass()) &&
-          !PsiClassImplUtil.isMainOrPremainMethod(method)) {
+          !isUsedMainOrPremainMethod(method)) {
         if (UnusedSymbolUtil.isInjected(project, method)) return;
         checkUnusedParameter(parameter, method);
         if (message != null) {
@@ -435,6 +435,20 @@ class PostHighlightingVisitor extends JavaElementVisitor {
     }
   }
 
+  private static boolean isUsedMainOrPremainMethod(@NotNull PsiMethod method) {
+    if (!PsiClassImplUtil.isMainOrPremainMethod(method)) {
+      return false;
+    }
+    //premain
+    if (!"main".equals(method.getName())) {
+      return true;
+    }
+    if (!HighlightingFeature.IMPLICIT_CLASSES.isAvailable(method)) {
+      return true;
+    }
+    return false;
+  }
+
   private void checkUnusedParameter(@NotNull PsiParameter parameter, @Nullable PsiMethod declarationMethod) {
     if (!myRefCountHolder.isReferenced(parameter) && !UnusedSymbolUtil.isImplicitUsage(myProject, parameter)) {
       message = JavaErrorBundle.message(parameter instanceof PsiPatternVariable ?

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedParameter/beforeMain.java

@@ -0,0 +1,6 @@
+// "Safe delete 'args'" "false"
+
+public class Main{
+  public static void main(String[] ar<caret>gs) {
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedParameterJava22Preview/afterMain.java

@@ -0,0 +1,6 @@
+// "Safe delete 'args'" "true-preview"
+
+public class Main{
+  public static void main() {
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedParameterJava22Preview/afterMainImplicitClass.java

@@ -0,0 +1,5 @@
+// "Safe delete 'args'" "true-preview"
+
+public static void main() {
+}
+

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedParameterJava22Preview/beforeMain.java

@@ -0,0 +1,6 @@
+// "Safe delete 'args'" "true-preview"
+
+public class Main{
+  public static void main(String[] arg<caret>s) {
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedParameterJava22Preview/beforeMainImplicitClass.java

@@ -0,0 +1,5 @@
+// "Safe delete 'args'" "true-preview"
+
+public static void main(String[] arg<caret>s) {
+}
+

java/java-tests/testSrc/com/intellij/codeInsight/daemon/impl/quickfix/RemoveUnusedParameterJava22PreviewTest.java

@@ -0,0 +1,27 @@
+// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.intellij.codeInsight.daemon.impl.quickfix;
+
+import com.intellij.codeInsight.daemon.quickFix.LightQuickFixParameterizedTestCase;
+import com.intellij.codeInspection.deadCode.UnusedDeclarationInspection;
+import com.intellij.pom.java.LanguageLevel;
+
+
+public class RemoveUnusedParameterJava22PreviewTest extends LightQuickFixParameterizedTestCase {
+
+  @Override
+  protected void setUp() throws Exception {
+    super.setUp();
+    enableInspectionTool(new UnusedDeclarationInspection());
+  }
+
+  @Override
+  protected String getBasePath() {
+    return "/codeInsight/daemonCodeAnalyzer/quickFix/removeUnusedParameterJava22Preview";
+  }
+
+  @Override
+  protected LanguageLevel getLanguageLevel() {
+    return LanguageLevel.JDK_22_PREVIEW;
+  }
+}
+