[java-generating] IDEA-345603 Generate -> override methods doesn't work with implicit classes

- allow to invoke everywhere in implicit classes
 - don't create {}
 - don't allow constructors

GitOrigin-RevId: 8f0b17b498035ffd1c20b26543de0a2d21eabf87

java/java-impl/src/com/intellij/codeInsight/generation/OverrideImplementUtil.java

@@ -789,13 +789,13 @@ public final class OverrideImplementUtil extends OverrideImplementExploreUtil {
     try {
       int offset = editor.getCaretModel().getOffset();
       PsiElement brace = aClass.getLBrace();
-      if (brace == null) {
+      if (brace == null && !(aClass instanceof PsiImplicitClass)) {
         PsiClass psiClass = JavaPsiFacade.getElementFactory(aClass.getProject()).createClass("X");
         brace = aClass.addRangeAfter(psiClass.getLBrace(), psiClass.getRBrace(), aClass.getLastChild());
         LOG.assertTrue(brace != null, aClass.getLastChild());
       }
 
-      int lbraceOffset = brace.getTextOffset();
+      int lbraceOffset = brace == null ? 0 : brace.getTextOffset();
       List<PsiGenerationInfo<PsiMethod>> resultMembers;
       if (offset <= lbraceOffset || aClass.isEnum()) {
         resultMembers = new ArrayList<>();
@@ -904,6 +904,13 @@ public final class OverrideImplementUtil extends OverrideImplementExploreUtil {
 
     final PsiClass aClass = (PsiClass)element;
     if (aClass instanceof PsiSyntheticClass) return null;
+    if (file instanceof PsiJavaFile javaFile) {
+      PsiClass[] classes = javaFile.getClasses();
+      if (classes.length == 1 && classes[0] instanceof PsiImplicitClass implicitClass &&
+          implicitClass.getFirstChild() != null && PsiMethodUtil.hasMainMethod(implicitClass)) {
+        return classes[0];
+      }
+    }
     return aClass == null || !allowInterface && aClass.isInterface() ? null : aClass;
   }
 

java/java-psi-impl/src/com/intellij/codeInsight/generation/OverrideImplementExploreUtil.java

@@ -65,7 +65,9 @@ public class OverrideImplementExploreUtil {
       PsiClass hisClass = method.getContainingClass();
       if (hisClass == null) continue;
       // filter non-immediate super constructors
-      if (method.isConstructor() && (!aClass.isInheritor(hisClass, false) || aClass instanceof PsiAnonymousClass || aClass.isEnum())) {
+      if (method.isConstructor() &&
+          (!aClass.isInheritor(hisClass, false) || aClass instanceof PsiAnonymousClass ||
+           aClass.isEnum() || aClass instanceof  PsiImplicitClass)) {
         continue;
       }
       // filter already implemented

java/java-tests/testData/codeInsight/overrideImplement/afterOverrideForImplicitClass.java

@@ -0,0 +1,29 @@
+public static void main(String[] args) {
+
+}
+
+@Override
+public int hashCode() {
+    <selection><caret>return super.hashCode();</selection>
+}
+
+@Override
+public boolean equals(Object obj) {
+    return super.equals(obj);
+}
+
+@Override
+protected Object clone() throws CloneNotSupportedException {
+    return super.clone();
+}
+
+@Override
+public String toString() {
+    return super.toString();
+}
+
+@Override
+protected void finalize() throws Throwable {
+    super.finalize();
+}
+

java/java-tests/testData/codeInsight/overrideImplement/beforeOverrideForImplicitClass.java

@@ -0,0 +1,5 @@
+public static void main(String[] args) {
+
+}
+
+<caret>

java/java-tests/testSrc/com/intellij/java/codeInsight/OverrideImplementTest.java

@@ -12,6 +12,8 @@ import com.intellij.openapi.command.CommandProcessor;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.PsiClass;
 import com.intellij.psi.PsiFile;
+import com.intellij.psi.PsiImplicitClass;
+import com.intellij.psi.PsiJavaFile;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.testFramework.LightProjectDescriptor;
 import com.intellij.testFramework.PsiTestUtil;
@@ -53,6 +55,10 @@ public class OverrideImplementTest extends LightJavaCodeInsightFixtureTestCase {
     doTest(false);
   }
 
+  public void testOverrideForImplicitClass() {
+    doTest(false);
+  }
+
   public void testImplementExtensionMethods() { doTest(true); }
 
   public void testOverrideExtensionMethods() { doTest(false); }
@@ -528,7 +534,12 @@ public class OverrideImplementTest extends LightJavaCodeInsightFixtureTestCase {
 
   private void invokeAction(boolean toImplement) {
     int offset = myFixture.getEditor().getCaretModel().getOffset();
-    PsiClass psiClass = PsiTreeUtil.findElementOfClassAtOffset(myFixture.getFile(), offset, PsiClass.class, false);
+    PsiFile psiFile = myFixture.getFile();
+    PsiClass psiClass = PsiTreeUtil.findElementOfClassAtOffset(psiFile, offset, PsiClass.class, false);
+    if (psiFile instanceof PsiJavaFile javaFile && javaFile.getClasses().length == 1 &&
+        javaFile.getClasses()[0] instanceof PsiImplicitClass implicitClass) {
+      psiClass = implicitClass;
+    }
     assertNotNull(psiClass);
     OverrideImplementUtil.chooseAndOverrideOrImplementMethods(getProject(), myFixture.getEditor(), psiClass, toImplement);
     NonBlockingReadActionImpl.waitForAsyncTaskCompletion();