[java, inspection] make unused symbol inspection not report main methods for unnamed classes IDEA-333152

GitOrigin-RevId: 1a1b41037a7bc28fc9a20620a182ca49ef789951

java/java-psi-impl/src/com/intellij/psi/impl/PsiClassImplUtil.java

@@ -313,15 +313,16 @@ public final class PsiClassImplUtil {
   }
 
   public static boolean isMainOrPremainMethod(@NotNull PsiMethod method) {
+    if (PsiMethodUtil.isMainMethod(method)) {
+      return true;
+    }
     String name = method.getName();
-    if (!("main".equals(name) || "premain".equals(name) || "agentmain".equals(name))) return false;
+    if ("premain".equals(name) || "agentmain".equals(name)) return false;
     if (!PsiTypes.voidType().equals(method.getReturnType())) return false;
 
     PsiElementFactory factory = JavaPsiFacade.getElementFactory(method.getProject());
     MethodSignature signature = method.getSignature(PsiSubstitutor.EMPTY);
     try {
-      MethodSignature main = createSignatureFromText(factory, "void main(String[] args);");
-      if (MethodSignatureUtil.areSignaturesEqual(signature, main)) return true;
       MethodSignature premain = createSignatureFromText(factory, "void premain(String args, java.lang.instrument.Instrumentation i);");
       if (MethodSignatureUtil.areSignaturesEqual(signature, premain)) return true;
       MethodSignature agentmain = createSignatureFromText(factory, "void agentmain(String args, java.lang.instrument.Instrumentation i);");

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/unusedDecls/UnnamedClassInstanceMainWithoutParams.java

@@ -0,0 +1 @@
+void main() {}

java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/UnusedSymbolLocalTest.java

@@ -21,7 +21,9 @@ import com.intellij.codeInspection.deadCode.UnusedDeclarationInspection;
 import com.intellij.lang.annotation.HighlightSeverity;
 import com.intellij.openapi.command.WriteCommandAction;
 import com.intellij.openapi.editor.Document;
+import com.intellij.pom.java.LanguageLevel;
 import com.intellij.psi.PsiDocumentManager;
+import com.intellij.testFramework.IdeaTestUtil;
 
 import java.util.Collection;
 
@@ -39,6 +41,16 @@ public class UnusedSymbolLocalTest extends DaemonAnalyzerTestCase {
   public void testInnerUsesSelf() throws Exception { doTest(); }
   public void testLocalClass() throws Exception { doTest(); }
   public void testPrivateConstructor() throws Exception { doTest(); }
+  public void testUnnamedClassInstanceMainWithoutParams() {
+    IdeaTestUtil.withLevel(myModule, LanguageLevel.JDK_21_PREVIEW, () -> {
+      try {
+        doTest();
+      }
+      catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+    });
+  }
 
   //@Bombed(day = 5, month = Calendar.SEPTEMBER, user = "anet")
   //public void testInjectedAnno() throws Exception { doTest(); }