Fix ClassCastException when data object is being analyzed

#KT-12687 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/OverrideResolver.java

@@ -286,7 +286,7 @@ public class OverrideResolver {
         }
     }
 
-    private void checkOverridesInAClass(@NotNull ClassDescriptorWithResolutionScopes classDescriptor, @NotNull final KtClassOrObject klass) {
+    private void checkOverridesInAClass(@NotNull ClassDescriptorWithResolutionScopes classDescriptor, @NotNull KtClassOrObject klass) {
         // Check overrides for internal consistency
         for (CallableMemberDescriptor member : classDescriptor.getDeclaredCallableMembers()) {
             checkOverrideForMember(member);
@@ -1056,7 +1056,7 @@ public class OverrideResolver {
 
     @NotNull
     private static PsiElement findDataModifierForDataClass(@NotNull DeclarationDescriptor dataClass) {
-        KtClass classDeclaration = (KtClass) DescriptorToSourceUtils.getSourceFromDescriptor(dataClass);
+        KtClassOrObject classDeclaration = (KtClassOrObject) DescriptorToSourceUtils.getSourceFromDescriptor(dataClass);
         if (classDeclaration != null && classDeclaration.getModifierList() != null) {
             PsiElement modifier = classDeclaration.getModifierList().getModifier(KtTokens.DATA_KEYWORD);
             if (modifier != null) {

compiler/testData/diagnostics/tests/dataClasses/dataObject.kt

@@ -0,0 +1 @@
+<!WRONG_MODIFIER_TARGET!>data<!> object Object<!CONSTRUCTOR_IN_OBJECT!>(val x: Int, val y: Int)<!>

compiler/testData/diagnostics/tests/dataClasses/dataObject.txt

@@ -0,0 +1,13 @@
+package
+
+public data object Object {
+    private constructor Object(/*0*/ x: kotlin.Int, /*1*/ y: kotlin.Int)
+    public final val x: kotlin.Int
+    public final val y: kotlin.Int
+    public final operator /*synthesized*/ fun component1(): kotlin.Int
+    public final operator /*synthesized*/ fun component2(): kotlin.Int
+    public final /*synthesized*/ fun copy(/*0*/ x: kotlin.Int = ..., /*1*/ y: kotlin.Int = ...): Object
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -4164,6 +4164,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("dataObject.kt")
+            public void testDataObject() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/dataClasses/dataObject.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("emptyConstructor.kt")
             public void testEmptyConstructor() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/dataClasses/emptyConstructor.kt");