K/N: Use class FQN in default toString() implementation

^KT-47167

kotlin-native/backend.native/tests/build.gradle

@@ -816,6 +816,10 @@ task tostring3(type: KonanLocalTest) {
     source = "runtime/basic/tostring3.kt"
 }
 
+task tostring4(type: KonanLocalTest) {
+    source = "runtime/basic/tostring4.kt"
+}
+
 task empty_substring(type: KonanLocalTest) {
     goldValue = "\n"
     source = "runtime/basic/empty_substring.kt"

kotlin-native/backend.native/tests/runtime/basic/tostring4.kt

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package runtime.basic.tostring4
+
+import kotlin.test.*
+
+class TopLevel
+
+@Test fun runTest() {
+    assertEquals("runtime.basic.tostring4.TopLevel", TopLevel().toStringWithoutHashCode())
+
+    class Local1
+    assertEquals("runtime.basic.tostring4.runTest\$Local1", Local1().toStringWithoutHashCode())
+
+    assertEquals("runtime.basic.tostring4.runTest\$1", object {}.toStringWithoutHashCode())
+
+    fun localFun() {
+        class Local2
+        assertEquals("runtime.basic.tostring4.runTest\$localFun\$Local2", Local2().toStringWithoutHashCode())
+
+        assertEquals("runtime.basic.tostring4.runTest\$localFun\$1", object {}.toStringWithoutHashCode())
+    }
+    localFun()
+}
+
+private fun Any.toStringWithoutHashCode(): String {
+    val string = toString()
+    assertEquals(1, string.count { it == '@' }, "Invalid toString() value: $string")
+    return string.substringBefore('@')
+}

kotlin-native/runtime/src/main/kotlin/kotlin/Any.kt

@@ -6,6 +6,7 @@
 package kotlin
 
 import kotlin.native.identityHashCode
+import kotlin.native.internal.fullName
 import kotlin.native.internal.ExportTypeInfo
 import kotlin.native.internal.GCUnsafeCall
 
@@ -41,8 +42,7 @@ public open class Any {
      * Returns a string representation of the object.
      */
     public open fun toString(): String {
-        val kClass = this::class
+        val className = this::class.fullName ?: "<object>"
-        val className = kClass.qualifiedName ?: kClass.simpleName ?: "<object>"
         // TODO: consider using [identityHashCode].
         val unsignedHashCode = this.hashCode().toLong() and 0xffffffffL
         val hashCodeStr = unsignedHashCode.toString(16)

kotlin-native/runtime/src/main/kotlin/kotlin/native/internal/KClassImpl.kt

@@ -27,20 +27,22 @@ internal class KClassImpl<T : Any>(private val typeInfo: NativePtr) : KClass<T>
 
     override fun hashCode(): Int = typeInfo.hashCode()
 
-    override fun toString(): String {
+    override fun toString(): String = "class ${fullName ?: "<anonymous>"}"
-        val relativeName = getRelativeName(typeInfo, false)
-        val visibleName = if (relativeName != null) {
-            val packageName = getPackageName(typeInfo, false)!!
-            if (packageName.isEmpty()) relativeName else "$packageName.$relativeName"
-        } else "<anonymous>"
 
-        return "class $visibleName"
+    internal val fullName: String?
-    }
+        get() {
+            val relativeName = getRelativeName(typeInfo, false) ?: return null
+            val packageName = getPackageName(typeInfo, false)!!
+            return if (packageName.isEmpty()) relativeName else "$packageName.$relativeName"
+        }
 
     internal fun findAssociatedObjectImpl(key: KClassImpl<*>): Any? =
             findAssociatedObjectImpl(this.typeInfo, key.typeInfo)
 }
 
+internal val KClass<*>.fullName: String?
+    get() = (this as? KClassImpl<*>)?.fullName
+
 @PublishedApi
 internal fun KClass<*>.findAssociatedObject(key: KClass<*>): Any? =
         if (this is KClassImpl<*> && key is KClassImpl<*>) {