Prohibit accessing nested classes/objects of class object using class literal

The fqname of class should be clear from code
Example: can't shorten A.Default.B.Default.C to A.B.C
Also fixes problem when nested class of enum class could be accessed via enum entry

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/CallableDescriptorCollectors.kt

@@ -43,22 +43,27 @@ private val FUNCTIONS_COLLECTOR = FunctionCollector.withDefaultFilter()
 private val VARIABLES_COLLECTOR = VariableCollector.withDefaultFilter()
 private val PROPERTIES_COLLECTOR = PropertyCollector.withDefaultFilter()
 
-public class CallableDescriptorCollectors<D : CallableDescriptor>(vararg collectors: CallableDescriptorCollector<D>) : Iterable<CallableDescriptorCollector<D>> {
-    private val collectors = collectors.toList()
+public class CallableDescriptorCollectors<D : CallableDescriptor>(val collectors: List<CallableDescriptorCollector<D>>) :
+        Iterable<CallableDescriptorCollector<D>> {
     override fun iterator(): Iterator<CallableDescriptorCollector<D>> = collectors.iterator()
 
     [suppress("UNCHECKED_CAST")]
     class object {
         public val FUNCTIONS_AND_VARIABLES: CallableDescriptorCollectors<CallableDescriptor> =
-                CallableDescriptorCollectors(FUNCTIONS_COLLECTOR as CallableDescriptorCollector<CallableDescriptor>,
-                                             VARIABLES_COLLECTOR as CallableDescriptorCollector<CallableDescriptor>)
+                CallableDescriptorCollectors(listOf(
+                        FUNCTIONS_COLLECTOR as CallableDescriptorCollector<CallableDescriptor>,
+                        VARIABLES_COLLECTOR as CallableDescriptorCollector<CallableDescriptor>
+                ))
         public val FUNCTIONS: CallableDescriptorCollectors<CallableDescriptor> =
-                CallableDescriptorCollectors(FUNCTIONS_COLLECTOR as CallableDescriptorCollector<CallableDescriptor>)
-        public val VARIABLES: CallableDescriptorCollectors<VariableDescriptor> = CallableDescriptorCollectors(VARIABLES_COLLECTOR)
-        public val PROPERTIES: CallableDescriptorCollectors<VariableDescriptor> = CallableDescriptorCollectors(PROPERTIES_COLLECTOR)
+                CallableDescriptorCollectors(listOf(FUNCTIONS_COLLECTOR as CallableDescriptorCollector<CallableDescriptor>))
+        public val VARIABLES: CallableDescriptorCollectors<VariableDescriptor> = CallableDescriptorCollectors(listOf(VARIABLES_COLLECTOR))
+        public val PROPERTIES: CallableDescriptorCollectors<VariableDescriptor> = CallableDescriptorCollectors(listOf(PROPERTIES_COLLECTOR))
     }
 }
 
+public fun <D : CallableDescriptor> CallableDescriptorCollectors<D>.filtered(filter: (D) -> Boolean): CallableDescriptorCollectors<D> =
+        CallableDescriptorCollectors(this.collectors.map { it.filtered(filter) })
+
 private object FunctionCollector : CallableDescriptorCollector<FunctionDescriptor> {
 
     override fun getNonExtensionsByName(scope: JetScope, name: Name, bindingTrace: BindingTrace): Collection<FunctionDescriptor> {

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/TaskPrioritizer.kt

@@ -23,8 +23,6 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.psi.Call
 import org.jetbrains.kotlin.resolve.calls.context.BasicCallResolutionContext
 import org.jetbrains.kotlin.resolve.calls.smartcasts.SmartCastUtils
-import org.jetbrains.kotlin.resolve.calls.tasks.collectors.CallableDescriptorCollector
-import org.jetbrains.kotlin.resolve.calls.tasks.collectors.CallableDescriptorCollectors
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.scopes.JetScope
 import org.jetbrains.kotlin.resolve.scopes.JetScopeUtils
@@ -39,6 +37,9 @@ import org.jetbrains.kotlin.resolve.calls.context.ResolutionContext
 import org.jetbrains.kotlin.resolve.calls.CallResolverUtil.isOrOverridesSynthesized
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind.*
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue.NO_RECEIVER
+import org.jetbrains.kotlin.resolve.*
+import org.jetbrains.kotlin.resolve.calls.util.*
+import org.jetbrains.kotlin.resolve.calls.tasks.collectors.*
 
 public class TaskPrioritizer(private val storageManager: StorageManager) {
 
@@ -71,10 +72,7 @@ public class TaskPrioritizer(private val storageManager: StorageManager) {
         if (explicitReceiver is QualifierReceiver) {
             val qualifierReceiver = explicitReceiver : QualifierReceiver
             doComputeTasks(NO_RECEIVER, taskPrioritizerContext.replaceScope(qualifierReceiver.getNestedClassesAndPackageMembersScope()))
-            val classObjectReceiver = qualifierReceiver.getClassObjectReceiver()
-            if (classObjectReceiver.exists()) {
-                doComputeTasks(classObjectReceiver, taskPrioritizerContext)
-            }
+            computeTasksForClassObjectReceiver(qualifierReceiver, taskPrioritizerContext)
         }
         else {
             doComputeTasks(explicitReceiver, taskPrioritizerContext)
@@ -83,6 +81,30 @@ public class TaskPrioritizer(private val storageManager: StorageManager) {
         return result.getTasks()
     }
 
+    private fun <D : CallableDescriptor, F : D> computeTasksForClassObjectReceiver(
+            qualifierReceiver: QualifierReceiver,
+            taskPrioritizerContext: TaskPrioritizerContext<D, F>
+    ) {
+        val classObjectReceiver = qualifierReceiver.getClassObjectReceiver()
+        if (!classObjectReceiver.exists()) {
+            return
+        }
+        val classifierDescriptor = qualifierReceiver.classifier
+        doComputeTasks(classObjectReceiver, taskPrioritizerContext.filterCollectors {
+            when {
+                classifierDescriptor is ClassDescriptor && classifierDescriptor.getDefaultObjectDescriptor() != null -> {
+                    // nested classes and objects should not be accessible via short reference to default object
+                    it !is ConstructorDescriptor && it !is FakeCallableDescriptorForObject
+                }
+                classifierDescriptor != null && DescriptorUtils.isEnumEntry(classifierDescriptor) -> {
+                    // objects nested in enum should not be accessible via enum entries reference
+                    it !is FakeCallableDescriptorForObject
+                }
+                else -> true
+            }
+        })
+    }
+
     private fun <D : CallableDescriptor, F : D> doComputeTasks(receiver: ReceiverValue, c: TaskPrioritizerContext<D, F>) {
         ProgressIndicatorProvider.checkCanceled()
 
@@ -428,5 +450,9 @@ public class TaskPrioritizer(private val storageManager: StorageManager) {
         fun replaceCollectors(newCollectors: CallableDescriptorCollectors<D>): TaskPrioritizerContext<D, F> {
             return TaskPrioritizerContext(name, result, context, scope, newCollectors)
         }
+
+        fun filterCollectors(filter: (D) -> Boolean): TaskPrioritizerContext<D, F> {
+            return TaskPrioritizerContext(name, result, context, scope, callableDescriptorCollectors.filtered(filter))
+        }
     }
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tasks/dynamicCalls.kt

@@ -252,6 +252,6 @@ class CollectorForDynamicReceivers<D: CallableDescriptor>(val delegate: Callable
     }
 }
 
-fun <D: CallableDescriptor> CallableDescriptorCollectors<D>.onlyDynamicReceivers(): CallableDescriptorCollectors<D> {
-    return CallableDescriptorCollectors(* this.map { CollectorForDynamicReceivers(it) }.copyToArray())
+fun <D : CallableDescriptor> CallableDescriptorCollectors<D>.onlyDynamicReceivers(): CallableDescriptorCollectors<D> {
+    return CallableDescriptorCollectors(this.map { CollectorForDynamicReceivers(it) })
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/scopes/receivers/Qualifier.kt

@@ -18,12 +18,10 @@ package org.jetbrains.kotlin.resolve.scopes.receivers
 
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.types.JetType
-import org.jetbrains.kotlin.resolve.scopes.JetScope
 import org.jetbrains.kotlin.psi.JetSimpleNameExpression
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.DescriptorUtils.getFqName
 import org.jetbrains.kotlin.name.Name
-import org.jetbrains.kotlin.resolve.scopes.ChainedScope
 import java.util.ArrayList
 import org.jetbrains.kotlin.utils.addIfNotNull
 import org.jetbrains.kotlin.resolve.BindingContext.*
@@ -35,6 +33,7 @@ import org.jetbrains.kotlin.psi.JetExpression
 import org.jetbrains.kotlin.resolve.bindingContextUtil.recordScopeAndDataFlowInfo
 import kotlin.properties.Delegates
 import org.jetbrains.kotlin.resolve.descriptorUtil.classObjectDescriptor
+import org.jetbrains.kotlin.resolve.scopes.*
 
 public trait Qualifier: ReceiverValue {
 
@@ -67,7 +66,10 @@ class QualifierReceiver (
     override var resultingDescriptor: DeclarationDescriptor by Delegates.notNull()
 
     override val scope: JetScope get() {
-        val scopes = listOf(classifier?.getClassObjectType()?.getMemberScope(), getNestedClassesAndPackageMembersScope()).filterNotNull().copyToArray()
+        val classObjectTypeScope = classifier?.getClassObjectType()?.getMemberScope()?.let {
+            FilteringScope(it) { it !is ClassDescriptor }
+        }
+        val scopes = listOf(classObjectTypeScope, getNestedClassesAndPackageMembersScope()).filterNotNull().copyToArray()
         return ChainedScope(descriptor, "Member scope for " + name + " as package or class or object", *scopes)
     }
 
@@ -82,12 +84,6 @@ class QualifierReceiver (
         if (classifier is ClassDescriptor) {
             scopes.add(classifier.getStaticScope())
 
-            val classObjectDescriptor = classifier.getDefaultObjectDescriptor()
-            if (classObjectDescriptor != null) {
-                // non-static members are resolved through class object receiver
-                scopes.add(DescriptorUtils.getStaticNestedClassesScope(classObjectDescriptor))
-            }
-
             if (classifier.getKind() != ClassKind.ENUM_ENTRY) {
                 scopes.add(DescriptorUtils.getStaticNestedClassesScope(classifier))
             }

compiler/testData/codegen/box/classes/kt249.kt

@@ -8,6 +8,6 @@ class Outer() {
 }
 
 fun box (): String {
-    val inner = Outer.Inner()
+    val inner = Outer.Default.Inner()
     return "OK"
 }

compiler/testData/codegen/box/enum/inclassobj.kt

@@ -1,4 +1,4 @@
-fun box() = if(Context.operatingSystemType == Context.OsType.OTHER) "OK" else "fail"
+fun box() = if(Context.operatingSystemType == Context.Default.OsType.OTHER) "OK" else "fail"
 
 public class Context
 {

compiler/testData/codegen/boxWithStdlib/whenEnumOptimization/enumInsideClassObject.kt

@@ -13,17 +13,17 @@ class A {
 
 fun foo(x : A.Default.Season) : String {
     return when (x) {
-        A.Season.WINTER -> "winter"
-        A.Season.SPRING -> "spring"
-        A.Season.SUMMER -> "summer"
+        A.Default.Season.WINTER -> "winter"
+        A.Default.Season.SPRING -> "spring"
+        A.Default.Season.SUMMER -> "summer"
         else -> "other"
     }
 }
 
 fun box() : String {
-    assertEquals("winter", foo(A.Season.WINTER))
-    assertEquals("spring", foo(A.Season.SPRING))
-    assertEquals("summer", foo(A.Season.SUMMER))
-    assertEquals("other", foo(A.Season.AUTUMN))
+    assertEquals("winter", foo(A.Default.Season.WINTER))
+    assertEquals("spring", foo(A.Default.Season.SPRING))
+    assertEquals("summer", foo(A.Default.Season.SUMMER))
+    assertEquals("other", foo(A.Default.Season.AUTUMN))
     return "OK"
 }

compiler/testData/diagnostics/tests/classObjects/ClassObjectVisibility.kt

@@ -2,7 +2,7 @@ package foo
 
 fun test() {
   A.d
-  A.<!INVISIBLE_MEMBER!>f<!>
+  A.Default.<!INVISIBLE_MEMBER!>f<!>
   B.<!INVISIBLE_MEMBER!>D<!>
   <!INVISIBLE_MEMBER!>CCC<!>
   CCC.<!INVISIBLE_MEMBER!>classObjectVar<!>

compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.kt

@@ -0,0 +1,51 @@
+package a
+
+class A {
+    class Nested
+    inner class Inner
+
+
+    class object {
+
+        class Nested2
+
+        val c: Int = 1
+
+        object Obj2 {
+            val c: Int = 1
+        }
+    }
+
+    object Obj
+}
+
+object O {
+    class A
+
+    object O
+}
+
+fun f() {
+    A.c
+    A.hashCode()
+    A().<!NO_CLASS_OBJECT, NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>Nested<!>
+    A.Nested()
+    A().Inner()
+    A.Default.<!UNRESOLVED_REFERENCE!>Nested<!>
+    A.Default.<!UNRESOLVED_REFERENCE!>Inner<!>
+    A.<!UNRESOLVED_REFERENCE!>Inner<!>
+    A.Default.c
+    A.Default.Obj2
+    A.Default.Obj2.c
+
+    A.Default.Nested2()
+    A.Default.c
+    A.Obj
+    A.Default.Obj2
+    A.<!UNRESOLVED_REFERENCE!>Obj2<!>
+    A.<!UNRESOLVED_REFERENCE!>Obj2<!>.<!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>c<!>
+    A.<!UNRESOLVED_REFERENCE!>Nested2<!>
+
+    O.O
+    O.A()
+}

compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.txt

@@ -0,0 +1,77 @@
+package
+
+package a {
+    internal fun f(): kotlin.Unit
+
+    internal final class A {
+        public constructor A()
+        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
+
+        internal class object Default {
+            private constructor Default()
+            internal final val c: kotlin.Int = 1
+            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
+
+            internal final class Nested2 {
+                public constructor Nested2()
+                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
+            }
+
+            internal object Obj2 {
+                private constructor Obj2()
+                internal final val c: kotlin.Int = 1
+                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
+            }
+        }
+
+        internal final inner class Inner {
+            public constructor Inner()
+            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
+        }
+
+        internal final class Nested {
+            public constructor Nested()
+            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
+        }
+
+        internal object Obj {
+            private constructor Obj()
+            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
+        }
+    }
+
+    internal object O {
+        private constructor O()
+        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
+
+        internal final class A {
+            public constructor A()
+            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
+        }
+
+        internal object O {
+            private constructor O()
+            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/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum.kt

@@ -0,0 +1,49 @@
+package a
+
+
+enum class C {
+    E1 E2 E3 {
+        object O_O
+
+        fun b() {
+            O_O
+        }
+
+        class G
+    }
+
+    E4 {
+        fun c() {
+            //TODO: this is a bug
+            this.<!UNRESOLVED_REFERENCE!>B<!>()
+
+            C.A()
+            A()
+            //TODO: this is a bug
+            this.<!UNRESOLVED_REFERENCE!>A<!>()
+        }
+    }
+
+    class A
+    inner class B
+    object O {
+        object InO
+    }
+}
+
+fun f() {
+    C.E1.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE, FUNCTION_CALL_EXPECTED!>A<!>
+    C.E1.<!NESTED_CLASS_ACCESSED_VIA_INSTANCE_REFERENCE!>A<!>()
+    C.E2.B()
+
+    C.E2.<!UNRESOLVED_REFERENCE!>O<!>
+    C.E3.<!UNRESOLVED_REFERENCE!>O<!>.<!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>InO<!>
+
+    C.O
+    C.O.InO
+    C.A()
+    C.<!UNRESOLVED_REFERENCE!>B<!>()
+
+    C.E3.<!UNRESOLVED_REFERENCE!>O_O<!>
+    C.E3.<!UNRESOLVED_REFERENCE!>G<!>()
+}

compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum.txt

@@ -0,0 +1,103 @@
+package
+
+package a {
+    internal fun f(): kotlin.Unit
+
+    internal final enum class C : kotlin.Enum<a.C> {
+        public enum entry E1 : a.C {
+            private constructor E1()
+            public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: a.C): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+            public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+            public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+            public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+        }
+
+        public enum entry E2 : a.C {
+            private constructor E2()
+            public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: a.C): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+            public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+            public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+            public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+        }
+
+        public enum entry E3 : a.C {
+            private constructor E3()
+            internal final fun b(): kotlin.Unit
+            public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: a.C): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+            public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+            public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+            public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+            internal final class G {
+                public constructor G()
+                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
+            }
+
+            internal object O_O {
+                private constructor O_O()
+                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
+            }
+        }
+
+        public enum entry E4 : a.C {
+            private constructor E4()
+            internal final fun c(): kotlin.Unit
+            public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: a.C): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+            public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+            public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+            public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+            public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+        }
+
+        private constructor C()
+        public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: a.C): kotlin.Int
+        public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public final override /*1*/ /*fake_override*/ fun name(): kotlin.String
+        public final override /*1*/ /*fake_override*/ fun ordinal(): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+        internal final class A {
+            public constructor A()
+            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
+        }
+
+        internal final inner class B {
+            public constructor B()
+            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
+        }
+
+        internal object O {
+            private constructor O()
+            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
+
+            internal object InO {
+                private constructor InO()
+                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
+            }
+        }
+
+        // Static members
+        public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): a.C
+        public final /*synthesized*/ fun values(): kotlin.Array<a.C>
+    }
+}

compiler/testData/diagnostics/tests/classObjects/nestedClassInPrivateClassObject.kt

@@ -10,6 +10,6 @@ class A {
     }
 }
 
-fun f1() = A.B.<!INVISIBLE_MEMBER!>C<!>
+fun f1() = A.Default.B.<!INVISIBLE_MEMBER!>C<!>
 
-fun f2() = A.B.C.<!INVISIBLE_MEMBER!>foo<!>()
+fun f2() = A.Default.B.C.<!INVISIBLE_MEMBER!>foo<!>()

compiler/testData/diagnostics/tests/multimodule/duplicateClass/duplicateNestedClasses.kt

@@ -21,10 +21,10 @@ public class M1 {
     public val a: A = A()
     public val b: A.B = A.B()
     public val c: A.C = A.C
-    public val d: A.Default.D = A.D()
-    public val e: A.Default.D.E = A.D.E
+    public val d: A.Default.D = A.Default.D()
+    public val e: A.Default.D.E = A.Default.D.E
     public val f: A.F = A().F()
-    public val g: A.Default.G = A.G()
+    public val g: A.Default.G = A.Default.G()
 }
 
 // MODULE: m2

compiler/testData/diagnostics/tests/objects/invokeOnInnerObject.kt

@@ -1,6 +1,6 @@
 //no nested class access via instance reference error
 fun test() {
-    A.f(<!TYPE_MISMATCH!>""<!>)
+    A.Default.f(<!TYPE_MISMATCH!>""<!>)
 }
 
 class A() {

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

@@ -1540,6 +1540,18 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("InnerClassAccessThroughClassObject.kt")
+            public void testInnerClassAccessThroughClassObject() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughClassObject.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("InnerClassAccessThroughEnum.kt")
+            public void testInnerClassAccessThroughEnum() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/classObjects/InnerClassAccessThroughEnum.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("InnerClassClassObject.kt")
             public void testInnerClassClassObject() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/classObjects/InnerClassClassObject.kt");

idea/testData/completion/basic/common/NestedClassesOnClassWithDefaultObject.kt

@@ -0,0 +1,27 @@
+class A {
+    class Nested
+    inner class Inner
+
+    class object {
+        class Nested2
+        val c: Int = 1
+        object Obj2
+
+        fun foo() {
+        }
+    }
+
+    object Obj
+}
+
+fun some() {
+    A.<caret>
+}
+
+// EXIST: Nested
+// EXIST: Default
+// EXIST: c
+// EXIST: foo
+// EXIST: Obj
+// ABSENT: Nested2
+// ABSENT: Obj2

idea/testData/completion/basic/common/NestedClassesOnClassWithNamedDefaultObject.kt

@@ -0,0 +1,27 @@
+class A {
+    class Nested
+    inner class Inner
+
+    class object Named {
+        class Nested2
+        val c: Int = 1
+        object Obj2
+
+        fun foo() {
+        }
+    }
+
+    object Obj
+}
+
+fun some() {
+    A.<caret>
+}
+
+// EXIST: Nested
+// EXIST: Named
+// EXIST: c
+// EXIST: foo
+// EXIST: Obj
+// ABSENT: Nested2
+// ABSENT: Obj2

idea/testData/completion/basic/common/NestedClassesOnDefaultObjectLiteral.kt

@@ -0,0 +1,27 @@
+class A {
+    class Nested
+    inner class Inner
+
+    class object Named {
+        class Nested2
+        val c: Int = 1
+        object Obj2
+
+        fun foo() {
+        }
+    }
+
+    object Obj
+}
+
+fun some() {
+    A.Named.<caret>
+}
+
+// EXIST: Nested2
+// EXIST: c
+// EXIST: foo
+// EXIST: Obj2
+// ABSENT: Nested
+// ABSENT: Named
+// ABSENT: Obj

idea/testData/completion/handlers/ClassFromClassObject.kt

@@ -5,5 +5,5 @@ class Test {
 }
 
 fun test() {
-    Test.S<caret>
+    Test.Default.S<caret>
 }

idea/testData/completion/handlers/ClassFromClassObject.kt.after

@@ -5,5 +5,5 @@ class Test {
 }
 
 fun test() {
-    Test.Some<caret>
+    Test.Default.Some
 }

idea/testData/completion/handlers/ClassFromClassObjectInPackage.kt

@@ -7,5 +7,5 @@ class Test {
 }
 
 fun test() {
-    a.Test.S<caret>
+    a.Test.Default.S<caret>
 }

idea/testData/completion/handlers/ClassFromClassObjectInPackage.kt.after

@@ -7,5 +7,5 @@ class Test {
 }
 
 fun test() {
-    a.Test.Some<caret>
+    a.Test.Default.Some<caret>
 }

idea/tests/org/jetbrains/kotlin/completion/JSBasicCompletionTestGenerated.java

@@ -613,6 +613,24 @@ public class JSBasicCompletionTestGenerated extends AbstractJSBasicCompletionTes
             doTest(fileName);
         }
 
+        @TestMetadata("NestedClassesOnClassWithDefaultObject.kt")
+        public void testNestedClassesOnClassWithDefaultObject() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NestedClassesOnClassWithDefaultObject.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("NestedClassesOnClassWithNamedDefaultObject.kt")
+        public void testNestedClassesOnClassWithNamedDefaultObject() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NestedClassesOnClassWithNamedDefaultObject.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("NestedClassesOnDefaultObjectLiteral.kt")
+        public void testNestedClassesOnDefaultObjectLiteral() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NestedClassesOnDefaultObjectLiteral.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("NoAutoInsertionOfNotImported.kt")
         public void testNoAutoInsertionOfNotImported() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NoAutoInsertionOfNotImported.kt");

idea/tests/org/jetbrains/kotlin/completion/JvmBasicCompletionTestGenerated.java

@@ -613,6 +613,24 @@ public class JvmBasicCompletionTestGenerated extends AbstractJvmBasicCompletionT
             doTest(fileName);
         }
 
+        @TestMetadata("NestedClassesOnClassWithDefaultObject.kt")
+        public void testNestedClassesOnClassWithDefaultObject() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NestedClassesOnClassWithDefaultObject.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("NestedClassesOnClassWithNamedDefaultObject.kt")
+        public void testNestedClassesOnClassWithNamedDefaultObject() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NestedClassesOnClassWithNamedDefaultObject.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("NestedClassesOnDefaultObjectLiteral.kt")
+        public void testNestedClassesOnDefaultObjectLiteral() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NestedClassesOnDefaultObjectLiteral.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("NoAutoInsertionOfNotImported.kt")
         public void testNoAutoInsertionOfNotImported() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/common/NoAutoInsertionOfNotImported.kt");