KT-4107 Data objects

compiler/testData/codegen/box/dataObjects/hashCode.kt

@@ -0,0 +1,19 @@
+// LANGUAGE: +DataObjects
+// WITH_STDLIB
+
+package com.example
+
+import kotlin.test.*
+
+data object DataObject {
+    data object Inner
+}
+
+fun box(): String {
+    assertEquals(DataObject.hashCode(), DataObject.hashCode())
+    assertNotEquals(DataObject.hashCode(), DataObject.Inner.hashCode())
+    assertNotEquals(0, DataObject.hashCode())
+    assertNotEquals(0, DataObject.Inner.hashCode())
+
+    return "OK"
+}