Rework class objects

Class objects have name "Default" by default
Do not produce synthetic class objects
Class objects have new semantics:
    class "A" has class object "B" if literal "A" can be used as a value of type "B"
Class objects act like ordinary nested objects
    i.e. are accessible from class scope via getClassifier()
Jvm backend: class object fields and class have the name of class object ("Default")
	as opposed to special "OBJECT$" and "object"
Serialization: only the name of class object is needed to serialize data

compiler/backend/src/org/jetbrains/kotlin/codegen/FieldInfo.java

@@ -32,16 +32,16 @@ public class FieldInfo {
             throw new UnsupportedOperationException("Can't create singleton field for class: " + classDescriptor);
         }
 
-        ClassDescriptor ownerDescriptor = kind == ClassKind.OBJECT
-                                          ? classDescriptor
-                                          : DescriptorUtils.getParentOfType(classDescriptor, ClassDescriptor.class);
-        assert ownerDescriptor != null : "Owner not found for class: " + classDescriptor;
-        Type ownerType = typeMapper.mapType(ownerDescriptor);
-
-        String fieldName = kind == ClassKind.ENUM_ENTRY
-                           ? classDescriptor.getName().asString()
-                           : classDescriptor.getKind() == ClassKind.CLASS_OBJECT ? JvmAbi.CLASS_OBJECT_FIELD : JvmAbi.INSTANCE_FIELD;
-        return new FieldInfo(ownerType, typeMapper.mapType(classDescriptor), fieldName, true);
+        if (kind == ClassKind.OBJECT) {
+            Type type = typeMapper.mapType(classDescriptor);
+            return new FieldInfo(type, type, JvmAbi.INSTANCE_FIELD, true);
+        }
+        else {
+            ClassDescriptor ownerDescriptor = DescriptorUtils.getParentOfType(classDescriptor, ClassDescriptor.class);
+            assert ownerDescriptor != null : "Owner not found for class: " + classDescriptor;
+            Type ownerType = typeMapper.mapType(ownerDescriptor);
+            return new FieldInfo(ownerType, typeMapper.mapType(classDescriptor), classDescriptor.getName().asString(), true);
+        }
     }
 
     @NotNull

compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java

@@ -958,7 +958,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
     }
 
     private void generateFieldForSingleton() {
-        if (isEnumEntry(descriptor)) return;
+        if (isEnumEntry(descriptor) || isClassObject(descriptor)) return;
 
         ClassDescriptor classObjectDescriptor = descriptor.getClassObjectDescriptor();
         ClassDescriptor fieldTypeDescriptor;

compiler/backend/src/org/jetbrains/kotlin/codegen/MemberCodegen.java

@@ -59,7 +59,6 @@ import static org.jetbrains.kotlin.codegen.AsmUtil.isPrimitive;
 import static org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.SYNTHESIZED;
 import static org.jetbrains.kotlin.descriptors.SourceElement.NO_SOURCE;
 import static org.jetbrains.kotlin.resolve.BindingContext.VARIABLE;
-import static org.jetbrains.kotlin.resolve.DescriptorUtils.isClassObject;
 import static org.jetbrains.kotlin.resolve.jvm.AsmTypes.*;
 import static org.jetbrains.kotlin.resolve.jvm.diagnostics.DiagnosticsPackage.OtherOrigin;
 import static org.jetbrains.kotlin.resolve.jvm.diagnostics.DiagnosticsPackage.TraitImpl;
@@ -242,9 +241,7 @@ public abstract class MemberCodegen<T extends JetElement/* TODO: & JetDeclaratio
         String outerClassInternalName =
                 containing instanceof ClassDescriptor ? typeMapper.mapClass((ClassDescriptor) containing).getInternalName() : null;
 
-        String innerName = isClassObject(innerClass)
-                           ? JvmAbi.CLASS_OBJECT_CLASS_NAME
-                           : innerClass.getName().isSpecial() ? null : innerClass.getName().asString();
+        String innerName = innerClass.getName().isSpecial() ? null : innerClass.getName().asString();
 
         String innerClassInternalName = typeMapper.mapClass(innerClass).getInternalName();
         v.visitInnerClass(innerClassInternalName, outerClassInternalName, innerName, calculateInnerClassAccessFlags(innerClass));

compiler/backend/src/org/jetbrains/kotlin/codegen/binding/CodegenAnnotatingVisitor.java

@@ -213,7 +213,8 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
         assert classDescriptor != null : String.format("No class found in binding context for: \n---\n%s\n---\n",
                                                        JetPsiUtil.getElementTextWithContext(classObject));
 
-        String name = peekFromStack(nameStack) + JvmAbi.CLASS_OBJECT_SUFFIX;
+        //TODO_R: remove visitClassObject
+        String name = getName(classDescriptor);
         recordClosure(classDescriptor, name);
 
         classStack.push(classDescriptor);

compiler/backend/src/org/jetbrains/kotlin/codegen/binding/PsiCodegenPredictor.java

@@ -80,7 +80,8 @@ public final class PsiCodegenPredictor {
 
         if (declaration instanceof JetClassObject) {
             // Get parent and assign Class object prefix
-            return parentInternalName + JvmAbi.CLASS_OBJECT_SUFFIX;
+            //TODO_R: getName() nullable
+            return parentInternalName + "$" + ((JetClassObject) declaration).getObjectDeclaration().getName();
         }
 
         if (!PsiTreeUtil.instanceOf(declaration, JetClass.class, JetObjectDeclaration.class, JetNamedFunction.class, JetProperty.class) ||

compiler/backend/src/org/jetbrains/kotlin/codegen/state/JetTypeMapper.java

@@ -339,14 +339,7 @@ public class JetTypeMapper {
         assert container instanceof ClassDescriptor : "Unexpected container: " + container + " for " + klass;
 
         String containerInternalName = computeAsmTypeImpl((ClassDescriptor) container);
-        switch (klass.getKind()) {
-            case ENUM_ENTRY:
-                return containerInternalName;
-            case CLASS_OBJECT:
-                return containerInternalName + JvmAbi.CLASS_OBJECT_SUFFIX;
-            default:
-                return containerInternalName + "$" + name;
-        }
+        return klass.getKind() == ClassKind.ENUM_ENTRY ? containerInternalName : containerInternalName + "$" + name;
     }
 
     @NotNull