CanSealedSubClassBeObjectInspection: don't report if sub-class has classModifier

#KT-38790 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/CanSealedSubClassBeObjectInspection.kt

@@ -46,6 +46,7 @@ class CanSealedSubClassBeObjectInspection : AbstractKotlinInspection() {
 
                 val candidates = klass.getSubclasses()
                     .withEmptyConstructors()
+                    .thatHasNoClassModifiers()
                     .thatAreFinal()
                     .thatHasNoTypeParameters()
                     .thatHasNoInnerClasses()
@@ -80,6 +81,13 @@ class CanSealedSubClassBeObjectInspection : AbstractKotlinInspection() {
             .filter { klass -> klass.secondaryConstructors.all { cons -> cons.valueParameters.isEmpty() } }.toList()
     }
 
+    private fun List<KtClass>.thatHasNoClassModifiers(): List<KtClass> {
+        return filter { klass ->
+            val modifierList = klass.modifierList ?: return@filter true
+            CLASS_MODIFIERS.none { modifierList.hasModifier(it) }
+        }
+    }
+
     private fun List<KtClass>.thatHasNoCompanionObjects(): List<KtClass> {
         return filter { klass -> klass.companionObjects.isEmpty() }
     }
@@ -110,7 +118,7 @@ class CanSealedSubClassBeObjectInspection : AbstractKotlinInspection() {
 
     private fun KtClass.hasNoStateOrEquals(): Boolean {
         if (primaryConstructor?.valueParameters?.isNotEmpty() == true) return false
-        val body = getBody()
+        val body = body
         return body == null || run {
             val declarations = body.declarations
             declarations.asSequence().filterIsInstance<KtProperty>().none { property ->
@@ -132,7 +140,7 @@ class CanSealedSubClassBeObjectInspection : AbstractKotlinInspection() {
     }
 
     private fun KtClass.hasNoInnerClass(): Boolean {
-        val internalClasses = getBody()
+        val internalClasses = body
             ?.declarations
             ?.filterIsInstance<KtClass>() ?: return true
 
@@ -143,5 +151,13 @@ class CanSealedSubClassBeObjectInspection : AbstractKotlinInspection() {
         val EQUALS = OperatorNameConventions.EQUALS.asString()
 
         const val HASH_CODE = "hashCode"
+
+        val CLASS_MODIFIERS = listOf(
+            KtTokens.ANNOTATION_KEYWORD,
+            KtTokens.DATA_KEYWORD,
+            KtTokens.ENUM_KEYWORD,
+            KtTokens.INNER_KEYWORD,
+            KtTokens.SEALED_KEYWORD,
+        )
     }
 }

idea/testData/inspectionsLocal/convertSealedSubClassToObject/annotation.kt

@@ -0,0 +1,5 @@
+// PROBLEM: none
+// DISABLE-ERRORS
+sealed class Bar
+
+annotation <caret>class Foo : Bar()

idea/testData/inspectionsLocal/convertSealedSubClassToObject/data.kt

@@ -0,0 +1,5 @@
+// PROBLEM: none
+// DISABLE-ERRORS
+sealed class Bar
+
+data <caret>class Foo : Bar()

idea/testData/inspectionsLocal/convertSealedSubClassToObject/enum.kt

@@ -0,0 +1,5 @@
+// PROBLEM: none
+// DISABLE-ERRORS
+sealed class Bar
+
+enum <caret>class Foo : Bar()

idea/testData/inspectionsLocal/convertSealedSubClassToObject/inner.kt

@@ -0,0 +1,5 @@
+// PROBLEM: none
+// DISABLE-ERRORS
+sealed class Bar
+
+inner <caret>class Foo : Bar()

idea/testData/inspectionsLocal/convertSealedSubClassToObject/sealed.kt

@@ -0,0 +1,4 @@
+// PROBLEM: none
+sealed class Bar
+
+sealed <caret>class Foo : Bar()

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -3385,6 +3385,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/inspectionsLocal/convertSealedSubClassToObject"), Pattern.compile("^([\\w\\-_]+)\\.(kt|kts)$"), null, true);
         }
 
+        @TestMetadata("annotation.kt")
+        public void testAnnotation() throws Exception {
+            runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/annotation.kt");
+        }
+
         @TestMetadata("baseEquals.kt")
         public void testBaseEquals() throws Exception {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/baseEquals.kt");
@@ -3415,6 +3420,16 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/convertSubClassWithoutParentheses.kt");
         }
 
+        @TestMetadata("data.kt")
+        public void testData() throws Exception {
+            runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/data.kt");
+        }
+
+        @TestMetadata("enum.kt")
+        public void testEnum() throws Exception {
+            runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/enum.kt");
+        }
+
         @TestMetadata("fakeState.kt")
         public void testFakeState() throws Exception {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/fakeState.kt");
@@ -3425,6 +3440,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/generic.kt");
         }
 
+        @TestMetadata("inner.kt")
+        public void testInner() throws Exception {
+            runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/inner.kt");
+        }
+
         @TestMetadata("noEquals.kt")
         public void testNoEquals() throws Exception {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/noEquals.kt");
@@ -3450,6 +3470,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/ownState.kt");
         }
 
+        @TestMetadata("sealed.kt")
+        public void testSealed() throws Exception {
+            runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/sealed.kt");
+        }
+
         @TestMetadata("sealedEquals.kt")
         public void testSealedEquals() throws Exception {
             runTest("idea/testData/inspectionsLocal/convertSealedSubClassToObject/sealedEquals.kt");