diff --git a/j2k/src/org/jetbrains/jet/j2k/CodeBuilder.kt b/j2k/src/org/jetbrains/jet/j2k/CodeBuilder.kt
index e4f9e98a417..6cfa7125b25 100644
--- a/j2k/src/org/jetbrains/jet/j2k/CodeBuilder.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/CodeBuilder.kt
@@ -21,7 +21,6 @@ import java.util.HashSet
 import org.jetbrains.jet.lang.psi.psiUtil.isAncestor
 import java.util.ArrayList
 import org.jetbrains.jet.j2k.ast.Element
-import org.jetbrains.jet.j2k.ast.Modifiers
 import kotlin.platform.platformName
 
 fun<T> CodeBuilder.append(generators: Collection<() -> T>, separator: String, prefix: String = "", suffix: String = ""): CodeBuilder {
@@ -79,14 +78,21 @@ class CodeBuilder(private val topElement: PsiElement?) {
     public fun append(element: Element): CodeBuilder {
         if (element.isEmpty) return this // do not insert comment and spaces for empty elements to avoid multiple blank lines
 
-        if (element.prototypes.isEmpty() || topElement == null) {
+        if (element.prototypes == null && topElement != null) {
+            val s = "Element $element has no prototypes assigned.\n" +
+                    "Use Element.assignPrototype() or Element.assignNoPrototype().\n" +
+                    "Element created at:\n${element.createdAt}"
+            throw RuntimeException(s)
+        }
+
+        if (topElement == null || element.prototypes!!.isEmpty()) {
             element.generateCode(this)
             return this
         }
 
         val prefixElements = ArrayList<PsiElement>(1)
         val postfixElements = ArrayList<PsiElement>(1)
-        for ((prototype, inheritBlankLinesBefore) in element.prototypes) {
+        for ((prototype, inheritBlankLinesBefore) in element.prototypes!!) {
             assert(prototype !is PsiComment)
             assert(prototype !is PsiWhiteSpace)
             assert(topElement.isAncestor(prototype))
@@ -112,7 +118,7 @@ class CodeBuilder(private val topElement: PsiElement?) {
         element.generateCode(this)
 
         // scan for all comments inside which are not yet used in the text and put them here to not loose any comment from code
-        for ((prototype, _) in element.prototypes) {
+        for ((prototype, _) in element.prototypes!!) {
             prototype.accept(object : JavaRecursiveElementVisitor(){
                 override fun visitComment(comment: PsiComment) {
                     if (commentsAndSpacesUsed.add(comment)) {
diff --git a/j2k/src/org/jetbrains/jet/j2k/Converter.kt b/j2k/src/org/jetbrains/jet/j2k/Converter.kt
index 34e60bd3847..db1a1a60199 100644
--- a/j2k/src/org/jetbrains/jet/j2k/Converter.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/Converter.kt
@@ -225,7 +225,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
                 var keepStatement = true
                 if (statement is AssignmentExpression) {
                     val assignee = statement.left
-                    if (assignee is QualifiedExpression && (assignee.qualifier as? Identifier)?.name == SecondaryConstructor.tempValIdentifier.name) {
+                    if (assignee is QualifiedExpression && (assignee.qualifier as? Identifier)?.name == SecondaryConstructor.tempValName) {
                         val name = (assignee.identifier as Identifier).name
                         for (field in finalOrWithEmptyInitializerFields) {
                             if (name == field.identifier.name) {
@@ -245,24 +245,27 @@ public class Converter private(val project: Project, val settings: ConverterSett
             }
 
             val initializer = MethodCallExpression.buildNotNull(null, className.name, finalOrWithEmptyInitializerFields.map { initializers[it]!! })
-            val localVar = LocalVariable(SecondaryConstructor.tempValIdentifier,
+            initializer.assignNoPrototype()
+            val localVar = LocalVariable(SecondaryConstructor.tempValIdentifier(),
                                          Annotations.Empty,
                                          Modifiers.Empty,
                                          { ClassType(className, listOf(), Nullability.NotNull, settings) },
                                          initializer,
                                          true,
-                                         settings)
-            newStatements.add(0, DeclarationStatement(listOf(localVar)))
-            constructor.block = Block(newStatements, LBrace(), RBrace())
+                                         settings).assignNoPrototype()
+            newStatements.add(0, DeclarationStatement(listOf(localVar)).assignNoPrototype())
+            constructor.block = Block(newStatements, LBrace().assignNoPrototype(), RBrace().assignNoPrototype()).assignNoPrototype()
         }
 
         //TODO: comments?
         val parameters = finalOrWithEmptyInitializerFields.map { field ->
             val varValModifier = if (field.isVal) Parameter.VarValModifier.Val else Parameter.VarValModifier.Var
-            Parameter(field.identifier, field.`type`, varValModifier, field.annotations, field.modifiers.filter { it in ACCESS_MODIFIERS })
+            Parameter(field.identifier, field.`type`, varValModifier, field.annotations, field.modifiers.filter { it in ACCESS_MODIFIERS }).assignPrototypesFrom(field)
         }
 
-        val primaryConstructor = PrimaryConstructor(this, Annotations.Empty, Modifiers(listOf(Modifier.PRIVATE)), ParameterList(parameters), Block.Empty)
+        val modifiers = Modifiers(listOf(Modifier.PRIVATE)).assignNoPrototype()
+        val parameterList = ParameterList(parameters).assignNoPrototype()
+        val primaryConstructor = PrimaryConstructor(this, Annotations.Empty, modifiers, parameterList, Block.Empty)
         val updatedMembers = classBody.normalMembers.filter { !finalOrWithEmptyInitializerFields.contains(it) }
         return ClassBody(primaryConstructor, classBody.secondaryConstructors, updatedMembers, classBody.classObjectMembers, classBody.lBrace, classBody.rBrace)
     }
@@ -330,7 +333,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
     private fun doConvertMethod(method: PsiMethod, membersToRemove: MutableSet<PsiMember>): Function {
         val returnType = typeConverter.convertMethodReturnType(method)
 
-        val annotations = convertAnnotations(method) + convertThrows(method)
+        val annotations = (convertAnnotations(method) + convertThrows(method)).assignNoPrototype()
         var modifiers = convertModifiers(method)
 
         if (method.isConstructor()) {
@@ -453,7 +456,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
                           convertAnnotations(parameter) + convertAnnotations(field),
                           convertModifiers(field).filter { it in ACCESS_MODIFIERS }).assignPrototypes(listOf(parameter, field), inheritBlankLinesBefore = false)
             }
-        })
+        }).assignPrototype(constructor.getParameterList())
         return PrimaryConstructor(this, annotations, modifiers, parameterList, block).assignPrototype(constructor)
     }
 
@@ -524,7 +527,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
     }
 
     fun convertTypeElement(element: PsiTypeElement?): TypeElement
-            = TypeElement(if (element == null) Type.Empty else typeConverter.convertType(element.getType())).assignPrototype(element)
+            = TypeElement(if (element == null) ErrorType().assignNoPrototype() else typeConverter.convertType(element.getType())).assignPrototype(element)
 
     private fun convertToNotNullableTypes(types: Array<out PsiType?>): List<Type>
             = types.map { typeConverter.convertType(it, Nullability.NotNull) }
@@ -608,13 +611,13 @@ public class Converter private(val project: Project, val settings: ConverterSett
         }
 
         val list = annotations.map { convertAnnotation(it, owner is PsiLocalVariable) }.filterNotNull() //TODO: brackets are also needed for local classes
-        return Annotations(list, newLines)
+        return Annotations(list, newLines).assignNoPrototype()
     }
 
     private fun convertAnnotation(annotation: PsiAnnotation, brackets: Boolean): Annotation? {
         val qualifiedName = annotation.getQualifiedName()
         if (qualifiedName == CommonClassNames.JAVA_LANG_DEPRECATED && annotation.getParameterList().getAttributes().isEmpty()) {
-            return Annotation(Identifier("deprecated"), listOf(null to LiteralExpression("\"\"")), brackets).assignPrototype(annotation) //TODO: insert comment
+            return Annotation(Identifier("deprecated").assignNoPrototype(), listOf(null to LiteralExpression("\"\"").assignNoPrototype()), brackets).assignPrototype(annotation) //TODO: insert comment
         }
 
         val nameRef = annotation.getNameReferenceElement()
@@ -625,7 +628,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
             val method = annotationClass?.findMethodsByName(it.getName() ?: "value", false)?.firstOrNull()
             val expectedType = method?.getReturnType()
 
-            val attrName = it.getName()?.let { Identifier(it) }
+            val attrName = it.getName()?.let { Identifier(it).assignNoPrototype() }
             val value = it.getValue()
 
             val isVarArg = method == lastMethod /* converted to vararg in Kotlin */
@@ -638,7 +641,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
 
     private fun convertAttributeValue(value: PsiAnnotationMemberValue?, expectedType: PsiType?, isVararg: Boolean, isUnnamed: Boolean): List<Expression> {
         return when (value) {
-            is PsiExpression -> listOf(convertExpression(value as? PsiExpression, expectedType))
+            is PsiExpression -> listOf(convertExpression(value as? PsiExpression, expectedType).assignPrototype(value))
 
             is PsiArrayInitializerMemberValue -> {
                 val componentType = (expectedType as? PsiArrayType)?.getComponentType()
@@ -650,27 +653,35 @@ public class Converter private(val project: Project, val settings: ConverterSett
                     val expectedTypeConverted = typeConverter.convertType(expectedType)
                     if (expectedTypeConverted is ArrayType) {
                         val array = createArrayInitializerExpression(expectedTypeConverted, componentsConverted, needExplicitType = false)
-                        listOf(if (isVararg) StarExpression(array) else array)
+                        if (isVararg) {
+                            listOf(StarExpression(array.assignNoPrototype()).assignPrototype(value))
+                        }
+                        else {
+                            listOf(array.assignPrototype(value))
+                        }
                     }
                     else {
-                        listOf(DummyStringExpression(value.getText()!!))
+                        listOf(DummyStringExpression(value.getText()!!).assignPrototype(value))
                     }
                 }
             }
 
-            else -> listOf(DummyStringExpression(value?.getText() ?: ""))
+            else -> listOf(DummyStringExpression(value?.getText() ?: "").assignPrototype(value))
         }
     }
 
     private fun convertThrows(method: PsiMethod): Annotations {
         val throwsList = method.getThrowsList()
         val types = throwsList.getReferencedTypes()
+        val refElements = throwsList.getReferenceElements()
+        assert(types.size == refElements.size)
         if (types.isEmpty()) return Annotations.Empty
-        val annotation = Annotation(Identifier("throws"),
-                                    types.map { null to MethodCallExpression.buildNotNull(null, "javaClass", listOf(), listOf(typeConverter.convertType(it, Nullability.NotNull))) },
-                                    false)
-        return Annotations(listOf(annotation.assignPrototype(throwsList)),
-                           true)
+        val arguments = types.indices.map {
+            val convertedType = typeConverter.convertType(types[it], Nullability.NotNull)
+            null to MethodCallExpression.buildNotNull(null, "javaClass", listOf(), listOf(convertedType)).assignPrototype(refElements[it])
+        }
+        val annotation = Annotation(Identifier("throws").assignNoPrototype(), arguments, false)
+        return Annotations(listOf(annotation.assignPrototype(throwsList)), true).assignPrototype(throwsList)
     }
 
     private val TYPE_MAP: Map<String, String> = mapOf(
diff --git a/j2k/src/org/jetbrains/jet/j2k/TypeConverter.kt b/j2k/src/org/jetbrains/jet/j2k/TypeConverter.kt
index 4458f631e5c..1bbae9ac64b 100644
--- a/j2k/src/org/jetbrains/jet/j2k/TypeConverter.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/TypeConverter.kt
@@ -26,6 +26,8 @@ import org.jetbrains.jet.j2k.ast.Import
 import org.jetbrains.jet.j2k.ast.ImportList
 import org.jetbrains.jet.j2k.ast.assignPrototype
 import com.intellij.psi.CommonClassNames.JAVA_LANG_OBJECT
+import org.jetbrains.jet.j2k.ast.assignNoPrototype
+import org.jetbrains.jet.j2k.ast.ErrorType
 
 class TypeConverter(val settings: ConverterSettings, val conversionScope: ConversionScope) {
     private val nullabilityCache = HashMap<PsiElement, Nullability>()
@@ -40,12 +42,12 @@ class TypeConverter(val settings: ConverterSettings, val conversionScope: Conver
     private var importNames: Set<String> = setOf()
 
     public val importsToAdd: Collection<Import>
-        get() = classesToImport.map { Import(it) }
+        get() = classesToImport.map { Import(it).assignNoPrototype() }
 
     public fun convertType(`type`: PsiType?, nullability: Nullability = Nullability.Default): Type {
-        if (`type` == null) return Type.Empty
+        if (`type` == null) return ErrorType().assignNoPrototype()
 
-        val result = `type`.accept<Type>(TypeVisitor(this, importNames, classesToImport))!!
+        val result = `type`.accept<Type>(TypeVisitor(this, importNames, classesToImport))!!.assignNoPrototype()
         return when (nullability) {
             Nullability.NotNull -> result.toNotNullType()
             Nullability.Nullable -> result.toNullableType()
diff --git a/j2k/src/org/jetbrains/jet/j2k/Utils.kt b/j2k/src/org/jetbrains/jet/j2k/Utils.kt
index eee0ce84cfe..b866f27c523 100644
--- a/j2k/src/org/jetbrains/jet/j2k/Utils.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/Utils.kt
@@ -59,20 +59,22 @@ fun PsiModifierListOwner.nullabilityFromAnnotations(): Nullability {
 
 fun getDefaultInitializer(field: Field): Expression {
     val t = field.`type`
-    if (t.isNullable) {
-        return LiteralExpression("null")
+    val result = if (t.isNullable) {
+        LiteralExpression("null")
     }
-
-    if (t is PrimitiveType) {
-        when(t.name.name) {
-            "Boolean" -> return LiteralExpression("false")
-            "Char" -> return LiteralExpression("' '")
-            "Double" -> return MethodCallExpression.buildNotNull(LiteralExpression("0"), OperatorConventions.DOUBLE.toString())
-            "Float" -> return MethodCallExpression.buildNotNull(LiteralExpression("0"), OperatorConventions.FLOAT.toString())
+    else if (t is PrimitiveType) {
+        when (t.name.name) {
+            "Boolean" -> LiteralExpression("false")
+            "Char" -> LiteralExpression("' '")
+            "Double" -> MethodCallExpression.buildNotNull(LiteralExpression("0").assignNoPrototype(), OperatorConventions.DOUBLE.toString())
+            "Float" -> MethodCallExpression.buildNotNull(LiteralExpression("0").assignNoPrototype(), OperatorConventions.FLOAT.toString())
+            else -> LiteralExpression("0")
         }
     }
-
-    return LiteralExpression("0")
+    else {
+        LiteralExpression("0")
+    }
+    return result.assignNoPrototype()
 }
 
 fun isQualifierEmptyOrThis(ref: PsiReferenceExpression): Boolean {
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/Annotation.kt b/j2k/src/org/jetbrains/jet/j2k/ast/Annotation.kt
index 57b51cc5775..31172b2742c 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/Annotation.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/Annotation.kt
@@ -58,6 +58,8 @@ class Annotations(val annotations: List<Annotation>, val newLines: Boolean) : El
         }
     }
 
+    override val isEmpty: Boolean = annotations.isEmpty()
+
     fun plus(other: Annotations) = Annotations(annotations + other.annotations, newLines || other.newLines)
 
     class object {
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/Constructors.kt b/j2k/src/org/jetbrains/jet/j2k/ast/Constructors.kt
index 5c29743fb18..3a3da3bc732 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/Constructors.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/Constructors.kt
@@ -25,7 +25,7 @@ abstract class Constructor(
         modifiers: Modifiers,
         parameterList: ParameterList,
         block: Block
-) : Function(converter, Identifier.Empty, annotations, modifiers, Type.Empty, TypeParameterList.Empty, parameterList, block, false)
+) : Function(converter, Identifier.Empty, annotations, modifiers, ErrorType(), TypeParameterList.Empty, parameterList, block, false)
 
 class PrimaryConstructor(converter: Converter,
                          annotations: Annotations,
@@ -54,18 +54,22 @@ class SecondaryConstructor(converter: Converter,
 
     public fun toFactoryFunction(containingClass: Class?): Function {
         val statements = ArrayList(block?.statements ?: listOf())
-        statements.add(ReturnStatement(tempValIdentifier))
-        val block = Block(statements, block?.lBrace ?: LBrace(), block?.rBrace ?: RBrace())
-        val typeParameters = ArrayList<TypeParameter>()
-        if (containingClass != null) {
-            typeParameters.addAll(containingClass.typeParameterList.parameters)
+        statements.add(ReturnStatement(tempValIdentifier()).assignNoPrototype())
+        val newBlock = Block(statements, block?.lBrace ?: LBrace().assignNoPrototype(), block?.rBrace ?: RBrace().assignNoPrototype())
+        if (this.block != null) {
+            newBlock.assignPrototypesFrom(block!!)
         }
-        return Function(converter, Identifier("create"), annotations, modifiers,
-                        ClassType(containingClass?.name ?: Identifier.Empty, typeParameters, Nullability.NotNull, converter.settings),
-                        TypeParameterList(typeParameters), parameterList, block, false).assignPrototypesFrom(this)
+
+        val typeParameters = if (containingClass != null) containingClass.typeParameterList.parameters else listOf()
+        val typeParameterList = TypeParameterList(typeParameters).assignNoPrototype()
+
+        val returnType = ClassType(containingClass?.name ?: Identifier.Empty, typeParameters, Nullability.NotNull, converter.settings).assignNoPrototype()
+        return Function(converter, Identifier("create").assignNoPrototype(), annotations, modifiers,
+                        returnType, typeParameterList, parameterList, newBlock, false).assignPrototypesFrom(this)
     }
 
     class object {
-        public val tempValIdentifier: Identifier = Identifier("__", false)
+        public val tempValName: String = "__"
+        public fun tempValIdentifier(): Identifier = Identifier(tempValName, false).assignNoPrototype()
     }
 }
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/Element.kt b/j2k/src/org/jetbrains/jet/j2k/ast/Element.kt
index 2a1b4f526b4..08e3b67e822 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/Element.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/Element.kt
@@ -20,17 +20,23 @@ import org.jetbrains.jet.j2k.*
 import com.intellij.psi.PsiElement
 
 fun <TElement: Element> TElement.assignPrototype(prototype: PsiElement?, inheritBlankLinesBefore: Boolean = true): TElement {
-    assignPrototypeInfos(if (prototype != null) listOf(PrototypeInfo(prototype, inheritBlankLinesBefore)) else listOf())
+    prototypes = if (prototype != null) listOf(PrototypeInfo(prototype, inheritBlankLinesBefore)) else listOf()
     return this
 }
 
 fun <TElement: Element> TElement.assignPrototypes(prototypes: List<PsiElement>, inheritBlankLinesBefore: Boolean): TElement {
-    assignPrototypeInfos(prototypes.map { PrototypeInfo(it, inheritBlankLinesBefore) })
+    this.prototypes = prototypes.map { PrototypeInfo(it, inheritBlankLinesBefore) }
+    return this
+}
+
+fun <TElement: Element> TElement.assignNoPrototype(): TElement {
+    prototypes = listOf()
     return this
 }
 
 fun <TElement: Element> TElement.assignPrototypesFrom(element: Element): TElement {
-    assignPrototypeInfos(element.prototypes)
+    prototypes = element.prototypes
+    createdAt = element.createdAt
     return this
 }
 
@@ -43,12 +49,17 @@ fun Element.canonicalCode(): String {
 }
 
 abstract class Element {
-    public var prototypes: List<PrototypeInfo> = listOf()
-        private set
+    public var prototypes: List<PrototypeInfo>? = null
+      set(value) {
+          // no prototypes assigned to empty elements because they can be singleton instances (and they are not needed anyway)
+          if (isEmpty) {
+              $prototypes = listOf()
+              return
+          }
+          $prototypes = value
+      }
 
-    public fun assignPrototypeInfos(prototypes: List<PrototypeInfo>) {
-        this.prototypes = prototypes
-    }
+    public var createdAt: String = "Element creation stacktraces turned off. Uncomment initializer of Element.createdAt." //Exception().getStackTrace().joinToString("\n")
 
     /** This method should not be used anywhere except for CodeBuilder! Use CodeBuilder.append instead. */
     public abstract fun generateCode(builder: CodeBuilder)
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/Expressions.kt b/j2k/src/org/jetbrains/jet/j2k/ast/Expressions.kt
index eee1b070edf..df207704928 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/Expressions.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/Expressions.kt
@@ -116,6 +116,10 @@ class PolyadicExpression(val expressions: List<Expression>, val token: String) :
 }
 
 class LambdaExpression(val arguments: String?, val block: Block) : Expression() {
+    {
+        assignPrototypesFrom(block)
+    }
+
     override fun generateCode(builder: CodeBuilder) {
         builder append block.lBrace append " "
 
@@ -155,7 +159,7 @@ fun createArrayInitializerExpression(arrayType: ArrayType, initializers: List<Ex
         if (doubleOrFloatTypes.contains(afterReplace)) {
             if (initializer is LiteralExpression) {
                 if (!initializer.canonicalCode().contains(".")) {
-                    return LiteralExpression(initializer.literalText + ".0")
+                    return LiteralExpression(initializer.literalText + ".0").assignPrototypesFrom(initializer)
                 }
             }
             else {
@@ -165,7 +169,7 @@ fun createArrayInitializerExpression(arrayType: ArrayType, initializers: List<Ex
                     else -> null
                 }
                 if (conversionFunction != null) {
-                    return MethodCallExpression.buildNotNull(initializer, conversionFunction)
+                    return MethodCallExpression.buildNotNull(initializer, conversionFunction).assignNoPrototype()
                 }
             }
         }
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/MethodCallExpression.kt b/j2k/src/org/jetbrains/jet/j2k/ast/MethodCallExpression.kt
index 2ef4af8227a..924a55238a3 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/MethodCallExpression.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/MethodCallExpression.kt
@@ -57,8 +57,8 @@ class MethodCallExpression(
                          typeArguments: List<Type>,
                          isNullable: Boolean,
                          lambdaArgument: LambdaExpression? = null): MethodCallExpression {
-            val identifier = Identifier(methodName, false)
-            return MethodCallExpression(if (receiver != null) QualifiedExpression(receiver, identifier) else identifier,
+            val identifier = Identifier(methodName, false).assignNoPrototype()
+            return MethodCallExpression(if (receiver != null) QualifiedExpression(receiver, identifier).assignNoPrototype() else identifier,
                                         arguments,
                                         typeArguments,
                                         isNullable,
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/Statements.kt b/j2k/src/org/jetbrains/jet/j2k/ast/Statements.kt
index 91956cb8c85..8258f5420c9 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/Statements.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/Statements.kt
@@ -156,7 +156,10 @@ class SwitchContainer(val expression: Expression, val caseContainers: List<CaseC
 }
 
 class CaseContainer(val caseStatement: List<Element>, statements: List<Statement>) : Statement() {
-    private val block = Block(statements.filterNot { it is BreakStatement || it is ContinueStatement }, LBrace(), RBrace(), true)
+    private val block = run {
+        val filteredStatements = statements.filterNot { it is BreakStatement || it is ContinueStatement }
+        Block(filteredStatements, LBrace().assignNoPrototype(), RBrace().assignNoPrototype(), true).assignNoPrototype()
+    }
 
     override fun generateCode(builder: CodeBuilder) {
         builder.append(caseStatement, ", ").append(" -> ").append(block)
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/TypeParameters.kt b/j2k/src/org/jetbrains/jet/j2k/ast/TypeParameters.kt
index 049d69702ee..bcf79534282 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/TypeParameters.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/TypeParameters.kt
@@ -67,7 +67,7 @@ fun Converter.convertTypeParameter(psiTypeParameter: PsiTypeParameter): TypePara
 
 fun Converter.convertTypeParameterList(typeParameterList: PsiTypeParameterList?): TypeParameterList {
     return if (typeParameterList != null)
-        TypeParameterList(typeParameterList.getTypeParameters()!!.toList().map { convertTypeParameter(it) })
+        TypeParameterList(typeParameterList.getTypeParameters()!!.toList().map { convertTypeParameter(it) }).assignPrototype(typeParameterList)
     else
         TypeParameterList.Empty
 }
\ No newline at end of file
diff --git a/j2k/src/org/jetbrains/jet/j2k/ast/Types.kt b/j2k/src/org/jetbrains/jet/j2k/ast/Types.kt
index 344a4e02bdf..1e4e6fc71c2 100644
--- a/j2k/src/org/jetbrains/jet/j2k/ast/Types.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/ast/Types.kt
@@ -18,7 +18,7 @@ package org.jetbrains.jet.j2k.ast
 
 import org.jetbrains.jet.j2k.*
 
-fun Type.isUnit(): Boolean = this == Type.Unit
+fun Type.isUnit(): Boolean = this is UnitType
 
 enum class Nullability {
     Nullable
@@ -51,26 +51,6 @@ abstract class Type() : Element() {
 
     open fun toNullableType(): Type = this
 
-    object Empty : NotNullType() {
-        override fun generateCode(builder: CodeBuilder) {
-            builder.append("UNRESOLVED_TYPE")
-        }
-    }
-
-    object Unit: NotNullType() {
-        override fun generateCode(builder: CodeBuilder) {
-            builder.append("Unit")
-        }
-    }
-
-    object Null: Type() {
-        override val isNullable: Boolean = true
-
-        override fun generateCode(builder: CodeBuilder) {
-            builder.append("???")
-        }
-    }
-
     override fun equals(other: Any?): Boolean = other is Type && other.canonicalCode() == this.canonicalCode()
 
     override fun hashCode(): Int = canonicalCode().hashCode()
@@ -78,6 +58,26 @@ abstract class Type() : Element() {
     override fun toString(): String = canonicalCode()
 }
 
+class UnitType : NotNullType() {
+    override fun generateCode(builder: CodeBuilder) {
+        builder.append("Unit")
+    }
+}
+
+class NullType : Type() {
+    override val isNullable: Boolean = true
+
+    override fun generateCode(builder: CodeBuilder) {
+        builder.append("???")
+    }
+}
+
+class ErrorType : NotNullType() {
+    override fun generateCode(builder: CodeBuilder) {
+        builder.append("UNRESOLVED_TYPE")
+    }
+}
+
 class ClassType(val name: Identifier, val typeArgs: List<Element>, nullability: Nullability, settings: ConverterSettings)
   : MayBeNullableType(nullability, settings) {
 
@@ -85,8 +85,8 @@ class ClassType(val name: Identifier, val typeArgs: List<Element>, nullability:
         builder.append(name).append(typeArgs, ", ", "<", ">").append(isNullableStr)
     }
 
-    override fun toNotNullType(): Type = ClassType(name, typeArgs, Nullability.NotNull, settings)
-    override fun toNullableType(): Type = ClassType(name, typeArgs, Nullability.Nullable, settings)
+    override fun toNotNullType(): Type = ClassType(name, typeArgs, Nullability.NotNull, settings).assignPrototypesFrom(this)
+    override fun toNullableType(): Type = ClassType(name, typeArgs, Nullability.Nullable, settings).assignPrototypesFrom(this)
 }
 
 class ArrayType(val elementType: Type, nullability: Nullability, settings: ConverterSettings)
@@ -101,8 +101,8 @@ class ArrayType(val elementType: Type, nullability: Nullability, settings: Conve
         }
     }
 
-    override fun toNotNullType(): Type = ArrayType(elementType, Nullability.NotNull, settings)
-    override fun toNullableType(): Type = ArrayType(elementType, Nullability.Nullable, settings)
+    override fun toNotNullType(): Type = ArrayType(elementType, Nullability.NotNull, settings).assignPrototypesFrom(this)
+    override fun toNullableType(): Type = ArrayType(elementType, Nullability.Nullable, settings).assignPrototypesFrom(this)
 }
 
 class InProjectionType(val bound: Type) : NotNullType() {
diff --git a/j2k/src/org/jetbrains/jet/j2k/visitors/ElementVisitor.kt b/j2k/src/org/jetbrains/jet/j2k/visitors/ElementVisitor.kt
index 04ae75a7702..84c10c6ef77 100644
--- a/j2k/src/org/jetbrains/jet/j2k/visitors/ElementVisitor.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/visitors/ElementVisitor.kt
@@ -43,7 +43,7 @@ class ElementVisitor(private val converter: Converter) : JavaElementVisitor() {
     override fun visitReferenceElement(reference: PsiJavaCodeReferenceElement) {
         val types = typeConverter.convertTypes(reference.getTypeParameters())
         if (!reference.isQualified()) {
-            result = ReferenceElement(Identifier(reference.getReferenceName()!!), types)
+            result = ReferenceElement(Identifier(reference.getReferenceName()!!).assignNoPrototype(), types)
         }
         else {
             var code = Identifier.toKotlin(reference.getReferenceName()!!)
@@ -53,7 +53,7 @@ class ElementVisitor(private val converter: Converter) : JavaElementVisitor() {
                 code = Identifier.toKotlin(p.getReferenceName()!!) + "." + code
                 qualifier = p.getQualifier()
             }
-            result = ReferenceElement(Identifier(code), types)
+            result = ReferenceElement(Identifier(code).assignNoPrototype(), types)
         }
     }
 
diff --git a/j2k/src/org/jetbrains/jet/j2k/visitors/ExpressionVisitor.kt b/j2k/src/org/jetbrains/jet/j2k/visitors/ExpressionVisitor.kt
index 0fc68ee8b0c..002007477df 100644
--- a/j2k/src/org/jetbrains/jet/j2k/visitors/ExpressionVisitor.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/visitors/ExpressionVisitor.kt
@@ -78,7 +78,7 @@ class ExpressionVisitor(private val converter: Converter,
         val lhs = converter.convertExpression(expression.getLExpression())
         val rhs = converter.convertExpression(expression.getRExpression()!!, expression.getLExpression().getType())
         if (!secondOp.isEmpty()) {
-            result = AssignmentExpression(lhs, BinaryExpression(lhs, rhs, secondOp), " = ")
+            result = AssignmentExpression(lhs, BinaryExpression(lhs, rhs, secondOp).assignNoPrototype(), " = ")
         }
         else {
             result = AssignmentExpression(lhs, rhs, expression.getOperationSign().getText()!!)
@@ -173,16 +173,16 @@ class ExpressionVisitor(private val converter: Converter,
                     origin as JetNamedDeclaration
                 val parameterCount = target.getParameterList().getParameters().size
                 if (parameterCount == arguments.size) {
-                    val propertyName = Identifier(property.getName()!!, isNullable)
+                    val propertyName = Identifier(property.getName()!!, isNullable).assignNoPrototype()
                     val isExtension = property.isExtensionDeclaration()
                     val propertyAccess = if (isTopLevel) {
                         if (isExtension)
-                            QualifiedExpression(converter.convertExpression(arguments.firstOrNull()), propertyName)
+                            QualifiedExpression(converter.convertExpression(arguments.firstOrNull()), propertyName).assignNoPrototype()
                         else
                             propertyName
                     }
                     else {
-                        QualifiedExpression(converter.convertExpression(methodExpr.getQualifierExpression()), propertyName)
+                        QualifiedExpression(converter.convertExpression(methodExpr.getQualifierExpression()), propertyName).assignNoPrototype()
                     }
 
                     when(if (isExtension) parameterCount - 1 else parameterCount) {
@@ -266,8 +266,8 @@ class ExpressionVisitor(private val converter: Converter,
             // non-primary constructor converted to factory method in class object
             val reference = expression.getClassReference()
             val typeParameters = if (reference != null) typeConverter.convertTypes(reference.getTypeParameters()) else listOf()
-            return QualifiedExpression(Identifier(constructor.getName(), false),
-                                       MethodCallExpression.buildNotNull(null, "create", converter.convertExpressions(arguments), typeParameters))
+            return QualifiedExpression(Identifier(constructor.getName(), false).assignNoPrototype(),
+                                       MethodCallExpression.buildNotNull(null, "create", converter.convertExpressions(arguments), typeParameters).assignNoPrototype())
         }
 
         return NewClassExpression(converter.convertElement(classReference),
@@ -303,20 +303,20 @@ class ExpressionVisitor(private val converter: Converter,
         val target = expression.getReference()?.resolve()
         val isNullable = if (target is PsiVariable) typeConverter.variableNullability(target).isNullable(converter.settings) else false
         val referencedName = expression.getReferenceName()!!
-        var identifier: Expression = Identifier(referencedName, isNullable)
+        var identifier: Expression = Identifier(referencedName, isNullable).assignNoPrototype()
         val qualifier = expression.getQualifierExpression()
 
         val containingConstructor = expression.getContainingConstructor()
         val insideSecondaryConstructor = containingConstructor != null && !containingConstructor.isPrimaryConstructor()
 
         if (insideSecondaryConstructor && (expression.getReference()?.resolve() as? PsiField)?.getContainingClass() == containingConstructor!!.getContainingClass()) {
-            identifier = QualifiedExpression(SecondaryConstructor.tempValIdentifier, Identifier(referencedName, isNullable))
+            identifier = QualifiedExpression(SecondaryConstructor.tempValIdentifier(), Identifier(referencedName, isNullable).assignNoPrototype())
         }
         else if (insideSecondaryConstructor && expression.isThisConstructorCall()) {
-            identifier = Identifier("val __ = " + (containingConstructor?.getContainingClass()?.getNameIdentifier()?.getText() ?: ""))
+            identifier = Identifier("val __ = " + (containingConstructor?.getContainingClass()?.getNameIdentifier()?.getText() ?: "")).assignNoPrototype()
         }
         else if (qualifier != null && qualifier.getType() is PsiArrayType && referencedName == "length") {
-            identifier = Identifier("size", isNullable)
+            identifier = Identifier("size", isNullable).assignNoPrototype()
         }
         else if (qualifier != null) {
             if (referencedName == JvmAbi.CLASS_OBJECT_FIELD || referencedName == JvmAbi.INSTANCE_FIELD) {
@@ -362,13 +362,15 @@ class ExpressionVisitor(private val converter: Converter,
     }
 
     override fun visitSuperExpression(expression: PsiSuperExpression) {
-        val qualifier = expression.getQualifier()?.getReferenceName()
-        result = SuperExpression(if (qualifier != null) Identifier(qualifier) else Identifier.Empty)
+        val psiQualifier = expression.getQualifier()
+        val qualifier = psiQualifier?.getReferenceName()
+        result = SuperExpression(if (qualifier != null) Identifier(qualifier).assignPrototype(psiQualifier) else Identifier.Empty)
     }
 
     override fun visitThisExpression(expression: PsiThisExpression) {
-        val qualifier = expression.getQualifier()?.getReferenceName()
-        result = ThisExpression(if (qualifier != null) Identifier(qualifier) else Identifier.Empty)
+        val psiQualifier = expression.getQualifier()
+        val qualifier = psiQualifier?.getReferenceName()
+        result = ThisExpression(if (qualifier != null) Identifier(qualifier).assignPrototype(psiQualifier) else Identifier.Empty)
     }
 
     override fun visitTypeCastExpression(expression: PsiTypeCastExpression) {
diff --git a/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt b/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt
index 2bcdc76238e..3fc7a3e9e90 100644
--- a/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt
@@ -45,14 +45,16 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
                 result = MethodCallExpression.buildNotNull(null, "assert", listOf(condition, description))
             }
             else {
-                result = MethodCallExpression.build(null, "assert", listOf(condition), listOf(), false, LambdaExpression(null, Block(listOf(description), LBrace(), RBrace())))
+                val block = Block(listOf(description), LBrace().assignNoPrototype(), RBrace().assignNoPrototype())
+                val lambda = LambdaExpression(null, block.assignNoPrototype())
+                result = MethodCallExpression.build(null, "assert", listOf(condition), listOf(), false, lambda)
             }
         }
     }
 
     override fun visitBlockStatement(statement: PsiBlockStatement) {
         val block = converter.convertBlock(statement.getCodeBlock())
-        result = MethodCallExpression.build(null, "run", listOf(), listOf(), false, LambdaExpression(null, block))
+        result = MethodCallExpression.build(null, "run", listOf(), listOf(), false, LambdaExpression(null, block).assignNoPrototype())
     }
 
     override fun visitBreakStatement(statement: PsiBreakStatement) {
@@ -118,7 +120,10 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
                 && loopVar.getNameIdentifier() != null
                 && onceWritableIterator) {
             val end = converter.convertExpression((condition as PsiBinaryExpression).getROperand())
-            val endExpression = if (operationTokenType == JavaTokenType.LT) BinaryExpression(end, LiteralExpression("1"), "-") else end
+            val endExpression = if (operationTokenType == JavaTokenType.LT)
+                BinaryExpression(end, LiteralExpression("1").assignNoPrototype(), "-").assignNoPrototype()
+            else
+                end
             result = ForeachWithRangeStatement(loopVar.declarationIdentifier(),
                                                  converter.convertExpression(loopVar.getInitializer()),
                                                  endExpression,
@@ -142,7 +147,8 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
                 }
 
                 if (nameConflict) {
-                    Block(listOf(converter.convertStatement(body), updateConverted), LBrace(), RBrace(), true)
+                    val statements = listOf(converter.convertStatement(body), updateConverted)
+                    Block(statements, LBrace().assignNoPrototype(), RBrace().assignNoPrototype(), true).assignNoPrototype()
                 }
                 else {
                     val block = converter.convertBlock(body.getCodeBlock(), true)
@@ -150,18 +156,20 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
                 }
             }
             else {
-                Block(listOf(converter.convertStatement(body), updateConverted), LBrace(), RBrace(), true)
+                val statements = listOf(converter.convertStatement(body), updateConverted)
+                Block(statements, LBrace().assignNoPrototype(), RBrace().assignNoPrototype(), true).assignNoPrototype()
             }
             val whileStatement = WhileStatement(
-                    if (condition != null) converter.convertExpression(condition) else LiteralExpression("true"),
+                    if (condition != null) converter.convertExpression(condition) else LiteralExpression("true").assignNoPrototype(),
                     whileBody,
-                    statement.isInSingleLine())
+                    statement.isInSingleLine()).assignNoPrototype()
 
             if (initializationConverted.isEmpty) {
                 result = whileStatement
             }
             else {
-                val block = Block(listOf(initializationConverted, whileStatement), LBrace(), RBrace())
+                val statements = listOf(initializationConverted, whileStatement)
+                val block = Block(statements, LBrace().assignNoPrototype(), RBrace().assignNoPrototype()).assignNoPrototype()
                 result = MethodCallExpression.build(null, "run", listOf(), listOf(), false, LambdaExpression(null, block))
             }
         }
@@ -216,7 +224,7 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
         val result = ArrayList<CaseContainer>()
         var pendingLabels = ArrayList<Element>()
         var i = 0
-        var hasDefaultCase: Boolean = false
+        var hasDefaultCase = false
         for (ls in cases) {
             if (ls.size() > 0) {
                 var label = ls[0] as PsiSwitchLabelStatement
@@ -225,21 +233,19 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
                 // TODO assert("not a right index") {allSwitchStatements?.get(i) == label}
                 if (ls.size() > 1) {
                     pendingLabels.add(converter.convertStatement(label))
-                    val slice: List<PsiElement> = ls.subList(1, (ls.size()))
+                    val slice = ls.subList(1, (ls.size()))
 
                     fun convertStatements(elements: List<PsiElement>): List<Statement>
                             = elements.map { if (it is PsiStatement) converter.convertStatement(it) else null }.filterNotNull()
 
                     if (!containsBreak(slice)) {
-                        val statements = ArrayList(convertStatements(slice))
-                        statements.addAll(convertStatements(getAllToNextBreak(allSwitchStatements, i + ls.size())))
-                        result.add(CaseContainer(pendingLabels, statements))
-                        pendingLabels = ArrayList()
+                        val statements = convertStatements(slice) + convertStatements(getAllToNextBreak(allSwitchStatements, i + ls.size()))
+                        result.add(CaseContainer(pendingLabels, statements).assignNoPrototype())
                     }
                     else {
-                        result.add(CaseContainer(pendingLabels, convertStatements(slice)))
-                        pendingLabels = ArrayList()
+                        result.add(CaseContainer(pendingLabels, convertStatements(slice)).assignNoPrototype())
                     }
+                    pendingLabels = ArrayList()
                 }
                 else {
                     pendingLabels.add(converter.convertStatement(label))
@@ -247,8 +253,9 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
                 i += ls.size()
             }
         }
-        if (!hasDefaultCase)
-            result.add(CaseContainer(listOf(DefaultSwitchLabelStatement()), ArrayList()))
+        if (!hasDefaultCase) {
+            result.add(CaseContainer(listOf(DefaultSwitchLabelStatement().assignNoPrototype()), listOf()).assignNoPrototype())
+        }
         return result
     }
 
@@ -268,7 +275,7 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
             val catchBlockParameters = tryStatement.getCatchBlockParameters()
             catchBlocks.indices.map {
                 CatchStatement(converter.convertParameter(catchBlockParameters[it], Nullability.NotNull),
-                               converter.convertBlock(catchBlocks[it]))
+                               converter.convertBlock(catchBlocks[it])).assignNoPrototype()
             }
         }
         val finallyConverted = converter.convertBlock(tryStatement.getFinallyBlock())
@@ -292,7 +299,7 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
         val returns = collectReturns(tryBlock)
         //TODO: support other returns when non-local returns supported by Kotlin
         if (returns.size == 1 && returns.single() == tryBlock!!.getStatements().last()) {
-            wrapResultStatement = { ReturnStatement(it) }
+            wrapResultStatement = { ReturnStatement(it).assignPrototype(returns.single()) }
             converterForBody = converter.withStatementVisitor { object : StatementVisitor(it) {
                 override fun visitReturnStatement(statement: PsiReturnStatement) {
                     if (statement == returns.single()) {
@@ -310,14 +317,16 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
         for (variable in resourceVariables.reverse()) {
             val lambda = LambdaExpression(Identifier.toKotlin(variable.getName()!!), block)
             expression = MethodCallExpression.build(converter.convertExpression(variable.getInitializer()), "use", listOf(), listOf(), false, lambda)
-            block = Block(listOf(expression), LBrace(), RBrace())
+            expression.assignNoPrototype()
+            block = Block(listOf(expression), LBrace().assignNoPrototype(), RBrace().assignNoPrototype()).assignNoPrototype()
         }
 
         if (catchesConverted.isEmpty() && finallyConverted.isEmpty) {
             return wrapResultStatement(expression)
         }
 
-        return TryStatement(Block(listOf(wrapResultStatement(expression)), LBrace(), RBrace(), true), catchesConverted, finallyConverted)
+        block = Block(listOf(wrapResultStatement(expression)), LBrace().assignPrototype(tryBlock?.getLBrace()), RBrace().assignPrototype(tryBlock?.getRBrace()), true)
+        return TryStatement(block.assignPrototype(tryBlock), catchesConverted, finallyConverted)
     }
 
     private fun collectReturns(block: PsiCodeBlock?): Collection<PsiReturnStatement> {
diff --git a/j2k/src/org/jetbrains/jet/j2k/visitors/TypeVisitor.kt b/j2k/src/org/jetbrains/jet/j2k/visitors/TypeVisitor.kt
index 718835039df..c11ea5193d3 100644
--- a/j2k/src/org/jetbrains/jet/j2k/visitors/TypeVisitor.kt
+++ b/j2k/src/org/jetbrains/jet/j2k/visitors/TypeVisitor.kt
@@ -31,16 +31,16 @@ class TypeVisitor(private val converter: TypeConverter, private val importNames:
     override fun visitPrimitiveType(primitiveType: PsiPrimitiveType): Type {
         val name = primitiveType.getCanonicalText()
         return if (name == "void") {
-            Type.Unit
+            UnitType()
         }
         else if (PRIMITIVE_TYPES_NAMES.contains(name)) {
-            PrimitiveType(Identifier(StringUtil.capitalize(name)))
+            PrimitiveType(Identifier(StringUtil.capitalize(name)).assignNoPrototype())
         }
         else if (name == "null") {
-            Type.Null
+            NullType()
         }
         else {
-            PrimitiveType(Identifier(name))
+            PrimitiveType(Identifier(name).assignNoPrototype())
         }
     }
 
@@ -81,7 +81,7 @@ class TypeVisitor(private val converter: TypeConverter, private val importNames:
                 if (kotlinShortName == getShortName(javaClassName!!) && importNames.contains(getPackageName(javaClassName) + ".*")) {
                     classesToImport.add(kotlinClassName)
                 }
-                return Identifier(kotlinShortName)
+                return Identifier(kotlinShortName).assignNoPrototype()
             }
         }
 
@@ -95,11 +95,11 @@ class TypeVisitor(private val converter: TypeConverter, private val importNames:
                     result = Identifier.toKotlin(codeRefElement.getReferenceName()!!) + "." + result
                     qualifier = codeRefElement.getQualifier()
                 }
-                return Identifier(result)
+                return Identifier(result).assignNoPrototype()
             }
         }
 
-        return Identifier(classType.getClassName() ?: "")
+        return Identifier(classType.getClassName() ?: "").assignNoPrototype()
     }
 
     private fun getPackageName(className: String): String = className.substring(0, className.lastIndexOf('.'))