New J2K: implement mutability inference in post-processing

#KT-24293 fixed
#KT-19603 fixed

generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt

@@ -143,6 +143,7 @@ import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinConverterSingleFileTest
 import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.AbstractTextNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.inference.common.AbstractCommonConstraintCollectorTest
+import org.jetbrains.kotlin.nj2k.inference.mutability.AbstractMutabilityInferenceTest
 import org.jetbrains.kotlin.nj2k.inference.nullability.AbstractNullabilityInferenceTest
 import org.jetbrains.kotlin.noarg.AbstractBlackBoxCodegenTestForNoArg
 import org.jetbrains.kotlin.noarg.AbstractBytecodeListingTestForNoArg
@@ -1062,6 +1063,9 @@ fun main(args: Array<String>) {
         testClass<AbstractNullabilityInferenceTest> {
             model("inference/nullability")
         }
+        testClass<AbstractMutabilityInferenceTest> {
+            model("inference/mutability")
+        }
         testClass<AbstractNewJavaToKotlinCopyPasteConversionTest> {
             model("copyPaste", pattern = """^([^\.]+)\.java$""")
         }

generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt.183

@@ -161,6 +161,7 @@ import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinConverterSingleFileTest
 import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.AbstractTextNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.inference.common.AbstractCommonConstraintCollectorTest
+import org.jetbrains.kotlin.nj2k.inference.mutability.AbstractMutabilityInferenceTest
 import org.jetbrains.kotlin.nj2k.inference.nullability.AbstractNullabilityInferenceTest
 import org.jetbrains.kotlin.noarg.AbstractBlackBoxCodegenTestForNoArg
 import org.jetbrains.kotlin.noarg.AbstractBytecodeListingTestForNoArg
@@ -1005,6 +1006,9 @@ fun main(args: Array<String>) {
         testClass<AbstractNullabilityInferenceTest> {
             model("inference/nullability")
         }
+        testClass<AbstractMutabilityInferenceTest> {
+            model("inference/mutability")
+        }
         testClass<AbstractNewJavaToKotlinCopyPasteConversionTest> {
             model("copyPaste", pattern = """^([^\.]+)\.java$""")
         }

generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt.as34

@@ -145,6 +145,7 @@ import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinConverterSingleFileTest
 import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.AbstractTextNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.inference.common.AbstractCommonConstraintCollectorTest
+import org.jetbrains.kotlin.nj2k.inference.mutability.AbstractMutabilityInferenceTest
 import org.jetbrains.kotlin.nj2k.inference.nullability.AbstractNullabilityInferenceTest
 import org.jetbrains.kotlin.noarg.AbstractBlackBoxCodegenTestForNoArg
 import org.jetbrains.kotlin.noarg.AbstractBytecodeListingTestForNoArg
@@ -969,6 +970,9 @@ fun main(args: Array<String>) {
         testClass<AbstractNullabilityInferenceTest> {
             model("inference/nullability")
         }
+        testClass<AbstractMutabilityInferenceTest> {
+            model("inference/mutability")
+        }
         testClass<AbstractNewJavaToKotlinCopyPasteConversionTest> {
             model("copyPaste", pattern = """^([^\.]+)\.java$""")
         }

generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt.as35

@@ -145,6 +145,7 @@ import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinConverterSingleFileTest
 import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.AbstractTextNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.inference.common.AbstractCommonConstraintCollectorTest
+import org.jetbrains.kotlin.nj2k.inference.mutability.AbstractMutabilityInferenceTest
 import org.jetbrains.kotlin.nj2k.inference.nullability.AbstractNullabilityInferenceTest
 import org.jetbrains.kotlin.noarg.AbstractBlackBoxCodegenTestForNoArg
 import org.jetbrains.kotlin.noarg.AbstractBytecodeListingTestForNoArg
@@ -965,6 +966,9 @@ fun main(args: Array<String>) {
         testClass<AbstractNullabilityInferenceTest> {
             model("inference/nullability")
         }
+        testClass<AbstractMutabilityInferenceTest> {
+            model("inference/mutability")
+        }
         testClass<AbstractNewJavaToKotlinCopyPasteConversionTest> {
             model("copyPaste", pattern = """^([^\.]+)\.java$""")
         }

generators/tests/org/jetbrains/kotlin/generators/tests/GenerateTests.kt.as36

@@ -145,6 +145,7 @@ import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinConverterSingleFileTest
 import org.jetbrains.kotlin.nj2k.AbstractNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.AbstractTextNewJavaToKotlinCopyPasteConversionTest
 import org.jetbrains.kotlin.nj2k.inference.common.AbstractCommonConstraintCollectorTest
+import org.jetbrains.kotlin.nj2k.inference.mutability.AbstractMutabilityInferenceTest
 import org.jetbrains.kotlin.nj2k.inference.nullability.AbstractNullabilityInferenceTest
 import org.jetbrains.kotlin.noarg.AbstractBlackBoxCodegenTestForNoArg
 import org.jetbrains.kotlin.noarg.AbstractBytecodeListingTestForNoArg
@@ -965,6 +966,9 @@ fun main(args: Array<String>) {
         testClass<AbstractNullabilityInferenceTest> {
             model("inference/nullability")
         }
+        testClass<AbstractMutabilityInferenceTest> {
+            model("inference/mutability")
+        }
         testClass<AbstractNewJavaToKotlinCopyPasteConversionTest> {
             model("copyPaste", pattern = """^([^\.]+)\.java$""")
         }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/BoundTypeCalculator.kt

@@ -88,9 +88,7 @@ open class BoundTypeCalculatorImpl(
             valueParameters.map { parameter ->
                 parameter.typeReference?.typeElement?.let { typeElement ->
                     inferenceContext.typeElementToTypeVariable[typeElement]
-                }?.let { typeVariable ->
-                    typeVariable.asBoundType()
-                } ?: return null
+                }?.asBoundType() ?: return null
             }
         } else {
             descriptor.valueParameters.map { parameter ->
@@ -220,7 +218,12 @@ open class BoundTypeCalculatorImpl(
                 )
 
             is TypeParameterDescriptor -> {
-                val containingDeclaration = target.containingDeclaration
+                val containingDeclaration = target.containingDeclaration.let { container ->
+                    when (container) {
+                        is TypeAliasDescriptor -> container.classDescriptor
+                        else -> container
+                    } ?: container
+                }
                 when {
                     containingDeclaration == call?.candidateDescriptor?.original -> {
                         val returnTypeVariable = inferenceContext.typeElementToTypeVariable[
@@ -240,7 +243,7 @@ open class BoundTypeCalculatorImpl(
                     contextBoundType?.isReferenceToClass == true ->
                         contextBoundType.typeParameters.getOrNull(target.index)?.boundType
 
-                    // `this` or `super` call case
+                    // `this`, `super`, or constructor call cases
                     containingDeclaration == call?.candidateDescriptor.safeAs<ConstructorDescriptor>()?.constructedClass -> {
                         val returnTypeVariable = inferenceContext.typeElementToTypeVariable[
                                 call?.call?.typeArguments?.getOrNull(target.index)?.typeReference?.typeElement

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/Constraint.kt

@@ -54,8 +54,15 @@ class LiteralBound private constructor(val state: State) : ConstraintBound() {
     }
 }
 
-fun State.constraintBound(): LiteralBound = when (this) {
+fun State.constraintBound(): LiteralBound? = when (this) {
     State.LOWER -> LiteralBound.LOWER
     State.UPPER -> LiteralBound.UPPER
     State.UNKNOWN -> LiteralBound.UNKNOWN
+    State.UNUSED -> null
 }
+
+val ConstraintBound.isUnused
+    get() = when (this) {
+        is TypeVariableBound -> typeVariable.state == State.UNUSED
+        is LiteralBound -> state == State.UNUSED
+    }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/ConstraintBuilder.kt

@@ -40,7 +40,11 @@ class ConstraintBuilder(
 
     fun KtExpression.isTheSameTypeAs(other: State, priority: ConstraintPriority) {
         boundType().label.safeAs<TypeVariableLabel>()?.typeVariable?.let { typeVariable ->
-            constraints += EqualsConstraint(typeVariable.constraintBound(), other.constraintBound(), priority)
+            constraints += EqualsConstraint(
+                typeVariable.constraintBound(),
+                other.constraintBound() ?: return@let,
+                priority
+            )
         }
     }
 

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/ContextCollector.kt

@@ -16,7 +16,6 @@ import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.calls.callUtil.getType
 import org.jetbrains.kotlin.types.KotlinType
-import org.jetbrains.kotlin.types.typeUtil.isUnit
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 abstract class ContextCollector(private val resolutionFacade: ResolutionFacade) {
@@ -48,11 +47,7 @@ abstract class ContextCollector(private val resolutionFacade: ResolutionFacade)
             val typeElement = typeElement ?: return null
             val classReference = classReference() ?: NoClassReference
 
-            val state = when {
-                classReference.descriptor?.defaultType?.isUnit() == true -> State.LOWER
-                defaultState != null -> defaultState
-                else -> classReference.getState(typeElement)
-            }
+            val state = defaultState ?: classReference.getState(typeElement)
             val typeArguments =
                 if (classReference is DescriptorClassReference) {
                     typeElement.typeArgumentsAsTypes.zip(
@@ -65,22 +60,15 @@ abstract class ContextCollector(private val resolutionFacade: ResolutionFacade)
                     }
                 } else emptyList()
 
-            return if (state == null) {
-                BoundTypeImpl(
-                    GenericLabel(classReference),
-                    typeArguments
-                )
-            } else {
-                val typeVariable = TypeElementBasedTypeVariable(
-                    classReference,
-                    typeArguments,
-                    typeElement.toData() ?: return null,
-                    owner,
-                    state
-                )
-                typeElementToTypeVariable[typeElement] = typeVariable
-                typeVariable.asBoundType()
-            }
+            val typeVariable = TypeElementBasedTypeVariable(
+                classReference,
+                typeArguments,
+                typeElement.toData() ?: return null,
+                owner,
+                state
+            )
+            typeElementToTypeVariable[typeElement] = typeVariable
+            return typeVariable.asBoundType()
         }
 
         fun KotlinType.toBoundType(): BoundType? {
@@ -97,24 +85,18 @@ abstract class ContextCollector(private val resolutionFacade: ResolutionFacade)
                     }
                 } else emptyList()
 
-            return if (state == null) {
-                BoundTypeImpl(
-                    GenericLabel(classReference),
-                    typeArguments
-                )
-            } else {
-                val typeVariable = TypeBasedTypeVariable(
-                    classReference,
-                    typeArguments,
-                    this,
-                    state
-                )
-                typeBasedTypeVariables += typeVariable
-                typeVariable.asBoundType()
-            }
+
+            val typeVariable = TypeBasedTypeVariable(
+                classReference,
+                typeArguments,
+                this,
+                state
+            )
+            typeBasedTypeVariables += typeVariable
+            return typeVariable.asBoundType()
         }
 
-        val substitutors = mutableMapOf<ClassDescriptor, ClassSubstitutor>()
+        val substitutors = mutableMapOf<ClassDescriptor, SuperTypesSubstitutor>()
 
         fun isOrAsExpression(typeReference: KtTypeReference) {
             val typeElement = typeReference.typeElement ?: return
@@ -160,7 +142,7 @@ abstract class ContextCollector(private val resolutionFacade: ResolutionFacade)
                         val descriptor =
                             expression.resolveToDescriptorIfAny(resolutionFacade) ?: return@forEachDescendantOfType
                         substitutors[descriptor] =
-                            ClassSubstitutor.createFromKtClass(expression, resolutionFacade) ?: return@forEachDescendantOfType
+                            SuperTypesSubstitutor.createFromKtClass(expression, resolutionFacade) ?: return@forEachDescendantOfType
                         for (typeParameter in expression.typeParameters) {
                             val typeVariable = typeParameter.resolveToDescriptorIfAny(resolutionFacade)
                                 ?.safeAs<TypeParameterDescriptor>()
@@ -206,5 +188,5 @@ abstract class ContextCollector(private val resolutionFacade: ResolutionFacade)
         )
     }
 
-    abstract fun ClassReference.getState(typeElement: KtTypeElement?): State?
+    abstract fun ClassReference.getState(typeElement: KtTypeElement?): State
 }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/DebugPrinter.kt

@@ -35,6 +35,7 @@ class DebugPrinter(private val inferenceContext: InferenceContext) {
         State.LOWER -> "L"
         State.UPPER -> "U"
         State.UNKNOWN -> "?"
+        State.UNUSED -> "$"
     }
 
     fun BoundType.asString(): String = buildString {
@@ -71,11 +72,10 @@ class DebugPrinter(private val inferenceContext: InferenceContext) {
 
 
 private class Namer(inferenceContext: InferenceContext) {
-    val names = inferenceContext.typeVariables.mapIndexed { index, typeVariable ->
+    private val names = inferenceContext.typeVariables.mapIndexed { index, typeVariable ->
         typeVariable to "T$index"
     }.toMap()
 
-
     fun name(typeVariable: TypeVariable): String =
         names.getValue(typeVariable)
 }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/InferenceContext.kt

@@ -19,7 +19,7 @@ data class InferenceContext(
     val typeElementToTypeVariable: Map<KtTypeElement, TypeVariable>,
     val declarationToTypeVariable: Map<KtNamedDeclaration, TypeVariable>,
     val declarationDescriptorToTypeVariable: Map<DeclarationDescriptor, TypeVariable>,
-    val classSubstitutions: Map<ClassDescriptor, ClassSubstitutor>
+    val superTypesSubstitutions: Map<ClassDescriptor, SuperTypesSubstitutor>
 
 ) {
     fun isInConversionScope(childCandidate: PsiElement) = when (childCandidate) {

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/Solver.kt

@@ -25,7 +25,9 @@ internal class Solver(
                 println()
                 println("type variables:")
                 for (typeVariable in inferenceContext.typeVariables) {
-                    println("${typeVariable.name} := ${typeVariable.state}")
+                    if (typeVariable.state != State.UNUSED) {
+                        println("${typeVariable.name} := ${typeVariable.state}")
+                    }
                 }
                 println("---------------\n")
             }
@@ -33,6 +35,7 @@ internal class Solver(
 
     fun solveConstraints(constraints: List<Constraint>) {
         val mutableConstraints = constraints.toMutableList()
+        mutableConstraints.filterOutConstraintsWithUnusedState()
         var currentStep = ConstraintPriority.values().first()
 
         var i = 0
@@ -144,11 +147,11 @@ internal class Solver(
                 val (lower, upper) = constraint
                 if (lower is TypeVariableBound && lower.typeVariable.isFixed) {
                     somethingChanged = true
-                    constraint.subtype = lower.typeVariable.state.constraintBound()
+                    constraint.subtype = lower.typeVariable.state.constraintBound() ?: continue
                 }
                 if (upper is TypeVariableBound && upper.typeVariable.isFixed) {
                     somethingChanged = true
-                    constraint.supertype = upper.typeVariable.state.constraintBound()
+                    constraint.supertype = upper.typeVariable.state.constraintBound() ?: continue
                 }
             }
         }
@@ -190,5 +193,14 @@ internal class Solver(
         }
         return null
     }
+
+    private fun MutableList<Constraint>.filterOutConstraintsWithUnusedState() {
+        removeIf { constraint ->
+            when (constraint) {
+                is SubtypeConstraint -> constraint.subtype.isUnused || constraint.supertype.isUnused
+                is EqualsConstraint -> constraint.left.isUnused || constraint.right.isUnused
+            }
+        }
+    }
 }
 

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/State.kt

@@ -6,7 +6,14 @@
 package org.jetbrains.kotlin.nj2k.inference.common
 
 enum class State {
+    // lower state in the terms of subtyping relation,
+    // e.g., for nullability this is not null type as T <: T?
+    // for mutability this is MutableCollection as MutableCollection <: Collection
     LOWER,
+    // the same as with lower but upper
     UPPER,
-    UNKNOWN
+    // the type variable state is needed to be calculated
+    UNKNOWN,
+    // we don't need to infer state of that type variable
+    UNUSED
 }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/StateUpdater.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.nj2k.inference.common
 
+import org.jetbrains.kotlin.idea.util.application.runWriteAction
 import org.jetbrains.kotlin.psi.psiUtil.isAncestor
 
 abstract class StateUpdater {
@@ -14,12 +15,14 @@ abstract class StateUpdater {
         val deepComparator = Comparator<TypeElementBasedTypeVariable> { o1, o2 ->
             if (o1.typeElement.typeElement.isAncestor(o2.typeElement.typeElement)) 1 else -1
         }
-        for (typeVariable in inferenceContext
-            .typeVariables
+        val typeVariablesSortedByDeep = inferenceContext.typeVariables
             .filterIsInstance<TypeElementBasedTypeVariable>()
             .sortedWith(deepComparator)
-        ) {
-            typeVariable.updateState()
+
+        runWriteAction {
+            for (typeVariable in typeVariablesSortedByDeep) {
+                typeVariable.updateState()
+            }
         }
     }
 

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/SuperTypesSubstitutor.kt

@@ -14,12 +14,12 @@ import org.jetbrains.kotlin.psi.KtClassOrObject
 import org.jetbrains.kotlin.psi.KtTypeElement
 import org.jetbrains.kotlin.resolve.BindingContext
 
-class ClassSubstitutor(private val superTypes: Map<ClassifierDescriptor, Map<TypeParameterDescriptor, KtTypeElement>>) {
+class SuperTypesSubstitutor(private val superTypes: Map<ClassifierDescriptor, Map<TypeParameterDescriptor, KtTypeElement>>) {
     operator fun get(klass: ClassDescriptor, typeParameter: TypeParameterDescriptor): KtTypeElement? =
         superTypes[klass]?.get(typeParameter)
 
     companion object {
-        fun createFromKtClass(klass: KtClassOrObject, resolutionFacade: ResolutionFacade): ClassSubstitutor? {
+        fun createFromKtClass(klass: KtClassOrObject, resolutionFacade: ResolutionFacade): SuperTypesSubstitutor? {
             val superTypes =
                 klass.superTypeListEntries.map { superType ->
                     val typeReference = superType.typeReference ?: return null
@@ -31,7 +31,7 @@ class ClassSubstitutor(private val superTypes: Map<ClassifierDescriptor, Map<Typ
                         parameter to (argument.typeElement ?: return null)
                     }.toMap()
                 }.toMap()
-            return ClassSubstitutor(superTypes)
+            return SuperTypesSubstitutor(superTypes)
         }
     }
 }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/collectors/CommonConstraintsCollector.kt

@@ -10,10 +10,7 @@ import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptorIfAny
 import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
-import org.jetbrains.kotlin.nj2k.inference.common.BoundTypeCalculator
-import org.jetbrains.kotlin.nj2k.inference.common.ConstraintBuilder
-import org.jetbrains.kotlin.nj2k.inference.common.ConstraintPriority
-import org.jetbrains.kotlin.nj2k.inference.common.InferenceContext
+import org.jetbrains.kotlin.nj2k.inference.common.*
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.asAssignment
 import org.jetbrains.kotlin.resolve.bindingContextUtil.getTargetFunction
@@ -108,8 +105,9 @@ class CommonConstraintsCollector : ConstraintsCollector() {
                                 contextBoundType = loopRangeBoundType,
                                 inferenceContext = inferenceContext
                             ) ?: return
-                    loopParameterTypeVariable.isSubtypeOf(
-                        boundType.typeParameters.firstOrNull()?.boundType ?: return,
+
+                    boundType.typeParameters.firstOrNull()?.boundType?.isSubtypeOf(
+                        loopParameterTypeVariable.asBoundType(),
                         ConstraintPriority.ASSIGNMENT
                     )
                 }
@@ -131,5 +129,6 @@ class CommonConstraintsCollector : ConstraintsCollector() {
             ?.firstOrNull { it.valueParameters.isEmpty() }
             ?.original
             ?.returnType
+
     }
 }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/collectors/FunctionConstraintsCollector.kt

@@ -34,7 +34,7 @@ class FunctionConstraintsCollector(
         val classDescriptor = ktClass.resolveToDescriptorIfAny(resolutionFacade) ?: return
 
         val superFunctions = superFunctionsProvider.provideSuperFunctionDescriptors(element) ?: return
-        val substitutor = inferenceContext.classSubstitutions[classDescriptor] ?: return
+        val substitutor = inferenceContext.superTypesSubstitutions[classDescriptor] ?: return
 
         for (superFunction in superFunctions) {
             val superClass = superFunction.containingDeclaration as? ClassDescriptor ?: continue
@@ -68,7 +68,7 @@ class FunctionConstraintsCollector(
         typeElement: KtTypeElement,
         superType: KotlinType,
         superTypeElement: KtTypeElement?,
-        substitutor: ClassSubstitutor,
+        substitutor: SuperTypesSubstitutor,
         superClass: ClassDescriptor,
         inferenceContext: InferenceContext
     ) {

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/common/utils.kt

@@ -7,14 +7,10 @@ package org.jetbrains.kotlin.nj2k.inference.common
 
 import com.intellij.psi.PsiComment
 import com.intellij.psi.PsiElement
-import org.jetbrains.kotlin.idea.refactoring.isInterfaceClass
-import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.nj2k.*
-import org.jetbrains.kotlin.psi.KtFunction
 import org.jetbrains.kotlin.psi.KtTypeElement
 import org.jetbrains.kotlin.psi.KtTypeProjection
 import org.jetbrains.kotlin.psi.KtTypeReference
-import org.jetbrains.kotlin.psi.psiUtil.containingClassOrObject
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 fun PsiElement.getLabel(): JKElementInfoLabel? =
@@ -33,12 +29,12 @@ fun PsiElement.elementInfo(converterContext: NewJ2kConverterContext): List<JKEle
     }
 
 
-private fun KtTypeReference.hasUnknownLabel(context: NewJ2kConverterContext, unknownLabel: JKElementInfo) =
+inline fun KtTypeReference.hasUnknownLabel(context: NewJ2kConverterContext, isUnknownLabel: (JKTypeInfo) -> Boolean) =
     getLabel()?.let { label ->
-        unknownLabel in context.elementsInfoStorage.getInfoForLabel(label).orEmpty()
+        context.elementsInfoStorage.getInfoForLabel(label)?.any { it.safeAs<JKTypeInfo>()?.let(isUnknownLabel) == true }
     } ?: false
 
-fun KtTypeElement.hasUnknownLabel(context: NewJ2kConverterContext, unknownLabel: JKElementInfo) =
+inline fun KtTypeElement.hasUnknownLabel(context: NewJ2kConverterContext, isUnknownLabel: (JKTypeInfo) -> Boolean) =
     parent
         ?.safeAs<KtTypeReference>()
-        ?.hasUnknownLabel(context, unknownLabel) == true
+        ?.hasUnknownLabel(context, isUnknownLabel) == true

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/CallResolver.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.descriptors.CallableDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.resolveToCall
+import org.jetbrains.kotlin.idea.references.mainReference
+import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtReferenceExpression
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
+
+class CallResolver(private val fqNames: Set<FqName>) {
+    private val shortNames = fqNames.map { it.shortName().identifier }.toSet()
+
+    private fun CallableDescriptor.isMutatorCall(): Boolean {
+        if (fqNameOrNull() in fqNames) return true
+        return overriddenDescriptors.any { it.isMutatorCall() }
+    }
+
+    fun isNeededCall(expression: KtExpression, resolutionFacade: ResolutionFacade): Boolean {
+        val shortName = when (expression) {
+            is KtCallExpression -> expression.calleeExpression?.text
+            is KtReferenceExpression -> expression.text
+            else -> null
+        } ?: return false
+        if (shortName !in shortNames) return false
+        val call = expression.resolveToCall(resolutionFacade) ?: return false
+        return call.candidateDescriptor.isMutatorCall()
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityBoundTypeCalculator.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns.FQ_NAMES
+import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.nj2k.inference.common.BoundType
+import org.jetbrains.kotlin.nj2k.inference.common.BoundTypeCalculatorImpl
+import org.jetbrains.kotlin.nj2k.inference.common.BoundTypeEnhancer
+import org.jetbrains.kotlin.nj2k.inference.common.InferenceContext
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtQualifiedExpression
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
+
+class MutabilityBoundTypeCalculator(
+    private val resolutionFacade: ResolutionFacade,
+    enhancer: BoundTypeEnhancer
+) : BoundTypeCalculatorImpl(resolutionFacade, enhancer) {
+
+    private val callResolver = CallResolver(PRESERVING_MUTABILITY_FQ_NAMES)
+
+    override fun interceptCalculateBoundType(inferenceContext: InferenceContext, expression: KtExpression): BoundType? {
+        return when (expression) {
+            is KtQualifiedExpression -> {
+                val selector = expression.selectorExpression ?: return null
+                if (callResolver.isNeededCall(selector, resolutionFacade))
+                    expression.receiverExpression.boundType(inferenceContext)
+                else null
+            }
+            else -> null
+        }
+    }
+
+    companion object {
+        private val PRESERVING_MUTABILITY_FQ_NAMES = setOf(
+            FQ_NAMES.collection.child(Name.identifier("iterator")),
+            FQ_NAMES.list.child(Name.identifier("listIterator")),
+            FQ_NAMES.map.child(Name.identifier("entries")),
+            FQ_NAMES.map.child(Name.identifier("values"))
+        )
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityBoundTypeEnhancer.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.nj2k.inference.common.*
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
+import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.isFlexible
+
+class MutabilityBoundTypeEnhancer : BoundTypeEnhancer() {
+    override fun enhance(
+        expression: KtExpression,
+        boundType: BoundType,
+        inferenceContext: InferenceContext
+    ): BoundType = boundType
+
+    override fun enhanceKotlinType(
+        type: KotlinType,
+        boundType: BoundType,
+        allowLowerEnhancement: Boolean,
+        inferenceContext: InferenceContext
+    ): BoundType {
+        if (type.isFlexible()) return boundType
+        val fqName = type.constructor.declarationDescriptor?.fqNameOrNull()
+        val enhancement = when {
+            fqName in MutabilityStateUpdater.mutableToImmutable && allowLowerEnhancement -> State.LOWER
+            fqName in MutabilityStateUpdater.immutableToMutable -> State.UPPER
+            else -> null
+        }
+        return boundType.enhanceWith(enhancement)
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityConstraintBoundProvider.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.nj2k.inference.common.*
+
+class MutabilityConstraintBoundProvider : ConstraintBoundProviderImpl() {
+    override fun BoundTypeLabel.constraintBound(): ConstraintBound? = when (this) {
+        is TypeVariableLabel -> typeVariable.constraintBound()
+        is TypeParameterLabel -> null
+        is GenericLabel -> null
+        StarProjectionLabel -> null
+        NullLiteralLabel -> null
+        LiteralLabel -> null
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityConstraintsCollector.kt

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import com.intellij.psi.CommonClassNames
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns.FQ_NAMES
+import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.nj2k.inference.common.*
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.ConstraintsCollector
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtElement
+import org.jetbrains.kotlin.psi.KtQualifiedExpression
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
+
+class MutabilityConstraintsCollector : ConstraintsCollector() {
+    private val callResolver = CallResolver(MUTATOR_CALL_FQ_NAMES)
+
+    override fun ConstraintBuilder.collectConstraints(
+        element: KtElement,
+        boundTypeCalculator: BoundTypeCalculator,
+        inferenceContext: InferenceContext,
+        resolutionFacade: ResolutionFacade
+    ) {
+        when (element) {
+            is KtQualifiedExpression -> {
+                val callExpression = element.selectorExpression?.safeAs<KtCallExpression>() ?: return
+                if (callResolver.isNeededCall(callExpression, resolutionFacade)) {
+                    element.receiverExpression.isTheSameTypeAs(State.LOWER, ConstraintPriority.USE_AS_RECEIVER)
+                }
+            }
+        }
+    }
+
+    companion object {
+        private val MUTATOR_CALL_FQ_NAMES = setOf(
+            FQ_NAMES.mutableCollection.child(Name.identifier("add")),
+            FQ_NAMES.mutableCollection.child(Name.identifier("addAll")),
+            FQ_NAMES.mutableCollection.child(Name.identifier("remove")),
+            FQ_NAMES.mutableCollection.child(Name.identifier("removeAll")),
+            FQ_NAMES.mutableCollection.child(Name.identifier("retainAll")),
+            FQ_NAMES.mutableCollection.child(Name.identifier("clear")),
+            FQ_NAMES.mutableCollection.child(Name.identifier("removeIf")),
+
+            FQ_NAMES.mutableList.child(Name.identifier("addAll")),
+            FQ_NAMES.mutableList.child(Name.identifier("set")),
+
+            FQ_NAMES.mutableMap.child(Name.identifier("put")),
+            FQ_NAMES.mutableMap.child(Name.identifier("remove")),
+            FQ_NAMES.mutableMap.child(Name.identifier("putAll")),
+            FQ_NAMES.mutableMap.child(Name.identifier("clear")),
+            FQ_NAMES.mutableMap.child(Name.identifier("putIfAbsent")),
+            FQ_NAMES.mutableMap.child(Name.identifier("replace")),
+            FQ_NAMES.mutableMap.child(Name.identifier("replaceAll")),
+            FQ_NAMES.mutableMap.child(Name.identifier("computeIfAbsent")),
+            FQ_NAMES.mutableMap.child(Name.identifier("computeIfPresent")),
+            FQ_NAMES.mutableMap.child(Name.identifier("compute")),
+            FQ_NAMES.mutableMap.child(Name.identifier("merge")),
+
+            FQ_NAMES.mutableMapEntry.child(Name.identifier("setValue")),
+
+            FQ_NAMES.mutableIterator.child(Name.identifier("remove")),
+
+            FQ_NAMES.mutableListIterator.child(Name.identifier("set")),
+            FQ_NAMES.mutableListIterator.child(Name.identifier("add"))
+        )
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityContextCollector.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
+import org.jetbrains.kotlin.nj2k.NewJ2kConverterContext
+import org.jetbrains.kotlin.nj2k.inference.common.ClassReference
+import org.jetbrains.kotlin.nj2k.inference.common.ContextCollector
+import org.jetbrains.kotlin.nj2k.inference.common.State
+import org.jetbrains.kotlin.nj2k.inference.common.hasUnknownLabel
+import org.jetbrains.kotlin.psi.KtTypeElement
+
+class MutabilityContextCollector(
+    resolutionFacade: ResolutionFacade,
+    private val converterContext: NewJ2kConverterContext
+) : ContextCollector(resolutionFacade) {
+    override fun ClassReference.getState(typeElement: KtTypeElement?): State = when {
+        typeElement == null -> State.UNUSED
+        typeElement.hasUnknownLabel(converterContext) { it.unknownMutability } -> State.UNKNOWN
+        else -> State.UNUSED
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityDefaultStateProvider.kt

@@ -0,0 +1,15 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.nj2k.inference.common.DefaultStateProvider
+import org.jetbrains.kotlin.nj2k.inference.common.State
+import org.jetbrains.kotlin.nj2k.inference.common.TypeVariable
+
+class MutabilityDefaultStateProvider : DefaultStateProvider() {
+    override fun defaultStateFor(typeVariable: TypeVariable): State =
+        State.UPPER
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityStateUpdater.kt

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.nj2k.inference.common.State
+import org.jetbrains.kotlin.nj2k.inference.common.StateUpdater
+import org.jetbrains.kotlin.nj2k.inference.common.TypeElementBasedTypeVariable
+import org.jetbrains.kotlin.psi.KtNullableType
+import org.jetbrains.kotlin.psi.KtPsiFactory
+import org.jetbrains.kotlin.psi.KtTypeElement
+import org.jetbrains.kotlin.psi.KtUserType
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
+import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.SimpleType
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
+
+class MutabilityStateUpdater : StateUpdater() {
+    override fun TypeElementBasedTypeVariable.updateState() = when (state) {
+        State.LOWER -> changeState(toMutable = true)
+        State.UPPER -> changeState(toMutable = false)
+        else -> Unit
+    }
+
+    companion object {
+        fun TypeElementBasedTypeVariable.changeState(toMutable: Boolean) {
+            changeState(typeElement.typeElement, typeElement.type, toMutable)
+        }
+
+        fun changeState(typeElement: KtTypeElement, type: KotlinType, toMutable: Boolean) {
+            if (type !is SimpleType) return
+            val userTypeElement = when (typeElement) {
+                is KtUserType -> typeElement
+                is KtNullableType -> typeElement.innerType as? KtUserType
+                else -> null
+            } ?: return
+            val initialFqName = type.constructor
+                .declarationDescriptor
+                .safeAs<ClassDescriptor>()
+                ?.fqNameOrNull()
+                ?: return
+            val newFqName = when {
+                !toMutable && initialFqName in mutableToImmutable -> mutableToImmutable[initialFqName]
+                toMutable && initialFqName in immutableToMutable -> immutableToMutable[initialFqName]
+                else -> null
+            } ?: return
+            val factory = KtPsiFactory(typeElement)
+            userTypeElement.referenceExpression?.replace(factory.createSimpleName(newFqName.shortName().identifier))
+            userTypeElement.qualifier.safeAs<KtUserType>()?.replace(factory.createType(newFqName.parent().asString()).typeElement ?: return)
+        }
+
+        val mutableToImmutable = mapOf(
+            KotlinBuiltIns.FQ_NAMES.mutableIterator to KotlinBuiltIns.FQ_NAMES.iterator,
+            KotlinBuiltIns.FQ_NAMES.mutableCollection to KotlinBuiltIns.FQ_NAMES.collection,
+            KotlinBuiltIns.FQ_NAMES.mutableList to KotlinBuiltIns.FQ_NAMES.list,
+            KotlinBuiltIns.FQ_NAMES.mutableListIterator to KotlinBuiltIns.FQ_NAMES.listIterator,
+            KotlinBuiltIns.FQ_NAMES.mutableSet to KotlinBuiltIns.FQ_NAMES.set,
+            KotlinBuiltIns.FQ_NAMES.mutableMap to KotlinBuiltIns.FQ_NAMES.map,
+            KotlinBuiltIns.FQ_NAMES.mutableMapEntry to KotlinBuiltIns.FQ_NAMES.mapEntry
+        )
+
+        val immutableToMutable = mutableToImmutable.map { (key, value) -> value to key }.toMap()
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/nullability/NullabilityBoundTypeEnhancer.kt

@@ -30,19 +30,17 @@ class NullabilityBoundTypeEnhancer(private val resolutionFacade: ResolutionFacad
         expression: KtExpression,
         boundType: BoundType,
         inferenceContext: InferenceContext
-    ): BoundType {
-        return when {
-            expression.isNullExpression() ->
-                WithForcedStateBoundType(boundType, State.UPPER)
-            expression is KtCallExpression -> enhanceCallExpression(expression, boundType, inferenceContext)
-            expression is KtQualifiedExpression && expression.selectorExpression is KtCallExpression ->
-                enhanceCallExpression(expression.selectorExpression as KtCallExpression, boundType, inferenceContext)
-            expression is KtNameReferenceExpression ->
-                boundType.enhanceWith(expression.smartCastEnhancement())
-            expression is KtLambdaExpression ->
-                WithForcedStateBoundType(boundType, State.LOWER)
-            else -> boundType
-        }
+    ): BoundType = when {
+        expression.isNullExpression() ->
+            WithForcedStateBoundType(boundType, State.UPPER)
+        expression is KtCallExpression -> enhanceCallExpression(expression, boundType, inferenceContext)
+        expression is KtQualifiedExpression && expression.selectorExpression is KtCallExpression ->
+            enhanceCallExpression(expression.selectorExpression as KtCallExpression, boundType, inferenceContext)
+        expression is KtNameReferenceExpression ->
+            boundType.enhanceWith(expression.smartCastEnhancement())
+        expression is KtLambdaExpression ->
+            WithForcedStateBoundType(boundType, State.LOWER)
+        else -> boundType
     }
 
     private fun enhanceCallExpression(

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/nullability/NullabilityContextCollector.kt

@@ -7,20 +7,19 @@ package org.jetbrains.kotlin.nj2k.inference.nullability
 
 import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
 import org.jetbrains.kotlin.nj2k.NewJ2kConverterContext
-import org.jetbrains.kotlin.nj2k.UnknownNullability
 import org.jetbrains.kotlin.nj2k.inference.common.*
 import org.jetbrains.kotlin.psi.KtNullableType
 import org.jetbrains.kotlin.psi.KtTypeElement
-import org.jetbrains.kotlin.psi.KtTypeReference
-import org.jetbrains.kotlin.utils.addToStdlib.safeAs
+import org.jetbrains.kotlin.types.typeUtil.isUnit
 
 class NullabilityContextCollector(
     resolutionFacade: ResolutionFacade,
     private val converterContext: NewJ2kConverterContext
 ) : ContextCollector(resolutionFacade) {
-    override fun ClassReference.getState(typeElement: KtTypeElement?): State? = when {
+    override fun ClassReference.getState(typeElement: KtTypeElement?): State = when {
+        descriptor?.defaultType?.isUnit() == true -> State.LOWER
         typeElement == null -> State.UNKNOWN
-        typeElement.hasUnknownLabel(converterContext, UnknownNullability) -> State.UNKNOWN
+        typeElement.hasUnknownLabel(converterContext) { it.unknownNullability } -> State.UNKNOWN
         typeElement is KtNullableType -> State.UPPER
         else -> State.LOWER
     }

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/inference/nullability/NullabilityStateUpdater.kt

@@ -5,23 +5,18 @@
 
 package org.jetbrains.kotlin.nj2k.inference.nullability
 
-import org.jetbrains.kotlin.nj2k.inference.common.*
+import org.jetbrains.kotlin.nj2k.inference.common.State
+import org.jetbrains.kotlin.nj2k.inference.common.StateUpdater
+import org.jetbrains.kotlin.nj2k.inference.common.TypeElementBasedTypeVariable
 import org.jetbrains.kotlin.psi.KtNullableType
 import org.jetbrains.kotlin.psi.KtPsiFactory
 import org.jetbrains.kotlin.psi.KtTypeElement
-import org.jetbrains.kotlin.psi.psiUtil.isAncestor
 
 class NullabilityStateUpdater : StateUpdater() {
     override fun TypeElementBasedTypeVariable.updateState() = when (state) {
         State.LOWER -> changeState(toNullable = false)
         State.UPPER -> changeState(toNullable = true)
-        State.UNKNOWN -> {
-            if (typeElement is TypeParameterElementData) {
-                changeState(toNullable = false)
-            } else {
-                changeState(toNullable = true)
-            }
-        }
+        else -> Unit
     }
 
     private fun TypeElementBasedTypeVariable.changeState(toNullable: Boolean) {

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/postProcessing/J2kPostProcessor.kt

@@ -245,8 +245,9 @@ private val processings: List<NamedPostProcessingGroup> = listOf(
                 ),
                 runSingleTime = true
             ),
-            nullabilityProcessing,
-            clearUndefinedLabelsProcessing
+            NullabilityInferenceProcessing(),
+            MutabilityInferenceProcessing(),
+            clearUnknownLabelsProcessing
         )
     ),
     NamedPostProcessingGroup(
@@ -255,7 +256,7 @@ private val processings: List<NamedPostProcessingGroup> = listOf(
     ),
     NamedPostProcessingGroup(
         "Shortening fully-qualified references",
-        listOf(shortenReferencesProcessing)
+        listOf(ShortenReferenceProcessing())
     ),
     NamedPostProcessingGroup(
         "Converting POJOs to data classes",
@@ -285,7 +286,7 @@ private val processings: List<NamedPostProcessingGroup> = listOf(
         "Optimizing imports",
         listOf(
             optimizeImportsProcessing,
-            shortenReferencesProcessing
+            ShortenReferenceProcessing()
         )
     ),
     NamedPostProcessingGroup(

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/postProcessing/processings/InferenceProcessing.kt

@@ -0,0 +1,94 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.postProcessing.processings
+
+import com.intellij.openapi.command.CommandProcessor
+import com.intellij.openapi.editor.RangeMarker
+import kotlinx.coroutines.withContext
+import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
+import org.jetbrains.kotlin.idea.core.util.EDT
+import org.jetbrains.kotlin.idea.core.util.range
+import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
+import org.jetbrains.kotlin.idea.util.application.runReadAction
+import org.jetbrains.kotlin.nj2k.NewJ2kConverterContext
+import org.jetbrains.kotlin.nj2k.inference.common.BoundTypeCalculatorImpl
+import org.jetbrains.kotlin.nj2k.inference.common.ByInfoSuperFunctionsProvider
+import org.jetbrains.kotlin.nj2k.inference.common.ConstraintsCollectorAggregator
+import org.jetbrains.kotlin.nj2k.inference.common.InferenceFacade
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.CallExpressionConstraintCollector
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.CommonConstraintsCollector
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.FunctionConstraintsCollector
+import org.jetbrains.kotlin.nj2k.inference.mutability.*
+import org.jetbrains.kotlin.nj2k.inference.nullability.*
+import org.jetbrains.kotlin.nj2k.postProcessing.GeneralPostProcessing
+import org.jetbrains.kotlin.psi.KtElement
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.psiUtil.elementsInRange
+
+abstract class InferenceProcessing : GeneralPostProcessing {
+    final override suspend fun runProcessing(file: KtFile, rangeMarker: RangeMarker?, converterContext: NewJ2kConverterContext) {
+        val elements = if (rangeMarker != null) {
+            val range = rangeMarker.range ?: return
+            runReadAction { file.elementsInRange(range) }.filterIsInstance<KtElement>()
+        } else listOf(file)
+        val resolutionFacade = runReadAction { file.getResolutionFacade() }
+
+        withContext(EDT) {
+            CommandProcessor.getInstance().runUndoTransparentAction {
+                createInferenceFacade(resolutionFacade, converterContext).runOn(elements)
+            }
+        }
+    }
+
+    abstract fun createInferenceFacade(
+        resolutionFacade: ResolutionFacade,
+        converterContext: NewJ2kConverterContext
+    ): InferenceFacade
+}
+
+class NullabilityInferenceProcessing : InferenceProcessing() {
+    override fun createInferenceFacade(
+        resolutionFacade: ResolutionFacade,
+        converterContext: NewJ2kConverterContext
+    ): InferenceFacade = InferenceFacade(
+        NullabilityContextCollector(resolutionFacade, converterContext),
+        ConstraintsCollectorAggregator(
+            resolutionFacade,
+            NullabilityConstraintBoundProvider(),
+            listOf(
+                CommonConstraintsCollector(),
+                CallExpressionConstraintCollector(),
+                FunctionConstraintsCollector(ByInfoSuperFunctionsProvider(resolutionFacade, converterContext)),
+                NullabilityConstraintsCollector()
+            )
+        ),
+        BoundTypeCalculatorImpl(resolutionFacade, NullabilityBoundTypeEnhancer(resolutionFacade)),
+        NullabilityStateUpdater(),
+        NullabilityDefaultStateProvider()
+    )
+}
+
+class MutabilityInferenceProcessing : InferenceProcessing() {
+    override fun createInferenceFacade(
+        resolutionFacade: ResolutionFacade,
+        converterContext: NewJ2kConverterContext
+    ): InferenceFacade = InferenceFacade(
+        MutabilityContextCollector(resolutionFacade, converterContext),
+        ConstraintsCollectorAggregator(
+            resolutionFacade,
+            MutabilityConstraintBoundProvider(),
+            listOf(
+                CommonConstraintsCollector(),
+                CallExpressionConstraintCollector(),
+                FunctionConstraintsCollector(ByInfoSuperFunctionsProvider(resolutionFacade, converterContext)),
+                MutabilityConstraintsCollector()
+            )
+        ),
+        MutabilityBoundTypeCalculator(resolutionFacade, MutabilityBoundTypeEnhancer()),
+        MutabilityStateUpdater(),
+        MutabilityDefaultStateProvider()
+    )
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/postProcessing/processings/ShortenReferenceProcessing.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.postProcessing.processings
+
+import com.intellij.openapi.editor.RangeMarker
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.idea.core.ShortenReferences
+import org.jetbrains.kotlin.idea.refactoring.fqName.getKotlinFqName
+import org.jetbrains.kotlin.idea.references.mainReference
+import org.jetbrains.kotlin.nj2k.ImportStorage
+import org.jetbrains.kotlin.nj2k.NewJ2kConverterContext
+import org.jetbrains.kotlin.nj2k.postProcessing.SimplePostProcessing
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtQualifiedExpression
+
+class ShortenReferenceProcessing : SimplePostProcessing() {
+    private val filter = filter@{ element: PsiElement ->
+        when (element) {
+            is KtQualifiedExpression -> {
+                val fqName = element.selectorExpression?.mainReference?.resolve()?.getKotlinFqName()
+                    ?: return@filter ShortenReferences.FilterResult.PROCESS
+                if (ImportStorage.isImportNeeded(fqName)) ShortenReferences.FilterResult.PROCESS
+                else ShortenReferences.FilterResult.SKIP
+            }
+            else -> ShortenReferences.FilterResult.PROCESS
+        }
+    }
+
+    override fun applySimpleProcessing(file: KtFile, rangeMarker: RangeMarker?, converterContext: NewJ2kConverterContext) {
+        if (rangeMarker != null) {
+            if (rangeMarker.isValid) {
+                ShortenReferences.DEFAULT.process(file, rangeMarker.startOffset, rangeMarker.endOffset, filter)
+            }
+        } else {
+            ShortenReferences.DEFAULT.process(file, filter)
+        }
+    }
+}

nj2k/nj2k-services/src/org/jetbrains/kotlin/nj2k/postProcessing/processings/processings.kt

@@ -10,29 +10,12 @@ import com.intellij.psi.PsiComment
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiElementVisitor
 import com.intellij.psi.codeStyle.CodeStyleManager
-import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
-import org.jetbrains.kotlin.idea.core.ShortenReferences
 import org.jetbrains.kotlin.idea.core.util.range
 import org.jetbrains.kotlin.idea.formatter.commitAndUnblockDocument
-import org.jetbrains.kotlin.idea.refactoring.fqName.getKotlinFqName
-import org.jetbrains.kotlin.idea.references.mainReference
-import org.jetbrains.kotlin.nj2k.ImportStorage
 import org.jetbrains.kotlin.nj2k.asLabel
-import org.jetbrains.kotlin.nj2k.inference.common.BoundTypeCalculatorImpl
-import org.jetbrains.kotlin.nj2k.inference.common.ByInfoSuperFunctionsProvider
-import org.jetbrains.kotlin.nj2k.inference.common.ConstraintsCollectorAggregator
-import org.jetbrains.kotlin.nj2k.inference.common.InferenceFacade
-import org.jetbrains.kotlin.nj2k.inference.common.collectors.CallExpressionConstraintCollector
-import org.jetbrains.kotlin.nj2k.inference.common.collectors.CommonConstraintsCollector
-import org.jetbrains.kotlin.nj2k.inference.common.collectors.FunctionConstraintsCollector
-import org.jetbrains.kotlin.nj2k.inference.nullability.NullabilityBoundTypeEnhancer
-import org.jetbrains.kotlin.nj2k.inference.nullability.NullabilityConstraintsCollector
-import org.jetbrains.kotlin.nj2k.inference.nullability.NullabilityContextCollector
-import org.jetbrains.kotlin.nj2k.inference.nullability.NullabilityStateUpdater
 import org.jetbrains.kotlin.nj2k.postProcessing.postProcessing
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.elementsInRange
-import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 val formatCodeProcessing =
     postProcessing { file, rangeMarker, _ ->
@@ -47,33 +30,7 @@ val formatCodeProcessing =
         }
     }
 
-val nullabilityProcessing =
-    postProcessing { file, rangeMarker, converterContext ->
-        val resolutionFacade = file.getResolutionFacade()
-        val inferenceFacade = InferenceFacade(
-            NullabilityContextCollector(resolutionFacade, converterContext),
-            ConstraintsCollectorAggregator(
-                resolutionFacade,
-                NullabilityConstraintBoundProvider(),
-                listOf(
-                    CommonConstraintsCollector(),
-                    CallExpressionConstraintCollector(),
-                    FunctionConstraintsCollector(ByInfoSuperFunctionsProvider(resolutionFacade, converterContext)),
-                    NullabilityConstraintsCollector()
-                )
-            ),
-            BoundTypeCalculatorImpl(resolutionFacade, NullabilityBoundTypeEnhancer(resolutionFacade)),
-            NullabilityStateUpdater(),
-            NullabilityDefaultStateProvider()
-        )
-        val elements = if (rangeMarker != null) {
-            file.elementsInRange(rangeMarker.range ?: return@postProcessing).filterIsInstance<KtElement>()
-        } else listOf(file)
-
-        inferenceFacade.runOn(elements)
-    }
-
-val clearUndefinedLabelsProcessing =
+val clearUnknownLabelsProcessing =
     postProcessing { file, _, _ ->
         file.clearUndefinedLabels()
     }
@@ -94,23 +51,6 @@ private fun KtFile.clearUndefinedLabels() {
     comments.forEach { it.delete() }
 }
 
-val shortenReferencesProcessing =
-    postProcessing { file, rangeMarker, _ ->
-        val filter = filter@{ element: PsiElement ->
-            if (element !is KtQualifiedExpression) return@filter ShortenReferences.FilterResult.PROCESS
-            val fqName = element.selectorExpression?.mainReference?.resolve()?.getKotlinFqName()
-                ?: return@filter ShortenReferences.FilterResult.PROCESS
-            if (ImportStorage.isImportNeeded(fqName)) ShortenReferences.FilterResult.PROCESS
-            else ShortenReferences.FilterResult.SKIP
-        }
-        if (rangeMarker != null) {
-            if (rangeMarker.isValid) {
-                ShortenReferences.DEFAULT.process(file, rangeMarker.startOffset, rangeMarker.endOffset, filter)
-            }
-        } else {
-            ShortenReferences.DEFAULT.process(file, filter)
-        }
-    }
 
 val optimizeImportsProcessing =
     postProcessing { file, rangeMarker, _ ->

nj2k/src/org/jetbrains/kotlin/nj2k/GenerateJKTreeVisitorAndTransformer.kt

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+import java.io.File
+
+
+private val JK_ROOT = File("./nj2k/src/org/jetbrains/kotlin/nj2k/tree")
+
+private val JK_OUT_ROOT = File(JK_ROOT, "visitors")
+
+private val JK_TREE_FILES = listOf(
+    "declarations.kt",
+    "elements.kt",
+    "expressions.kt",
+    "modifiers.kt",
+    "statements.kt"
+).map { File(JK_ROOT, it) }
+
+
+val elementRegex = """(class|object)\s+(JK[\w]+)(\([\w\s:,<>=\(\)\\]+\))?\s*:\s*(JK[a-zA-Z]+)""".toRegex()
+
+
+data class InterfaceData(val name: String, val extends: String?)
+
+fun File.interfaceNames() =
+    sequenceOf(this)
+        .map { it.readText() }
+        .flatMap { elementRegex.findAll(it) }
+        .map { match ->
+            InterfaceData(
+                match.groupValues[2],
+                match.groupValues[4].let { if (it == "JKAnnotationMemberValue") "JKTreeElement" else it }
+            )
+        }.toList()
+
+
+fun String.safeVarName() = when (this) {
+    "class" -> "klass"
+    else -> this
+}
+
+fun genVisitors(
+    interfaceData: List<InterfaceData>,
+    visitorName: String
+) {
+    val pkg = "package org.jetbrains.kotlin.nj2k.tree.visitors"
+
+    File(JK_OUT_ROOT, "$visitorName.kt").writeText(buildString {
+        appendln(pkg)
+        appendln()
+        appendln("import org.jetbrains.kotlin.nj2k.tree.*")
+        appendln()
+        appendln("abstract class $visitorName {")
+        interfaceData.joinTo(this, separator = "\n") { (name, ext) ->
+            val nameWithoutPrefix = name.removePrefix("JK")
+            val argName = nameWithoutPrefix.decapitalize().safeVarName()
+            val generifyCall = if (name != "JKTreeElement") "= visit${ext?.removePrefix("JK") ?: error(name)}($argName)" else ""
+            val modifier = if (name == "JKTreeElement") "abstract" else "open"
+            """
+            |    $modifier fun visit$nameWithoutPrefix($argName: $name) $generifyCall
+            """.trimMargin()
+        }
+        appendln()
+        appendln("}")
+    })
+
+
+    File(JK_OUT_ROOT, "${visitorName}WithCommentsPrinting.kt").writeText(buildString {
+        appendln(pkg)
+        appendln()
+        appendln("import org.jetbrains.kotlin.nj2k.tree.*")
+        appendln()
+
+        appendln("abstract class ${visitorName}WithCommentsPrinting : $visitorName() {")
+        appendln(
+            """
+        |    abstract fun printLeftNonCodeElements(element: JKNonCodeElementsListOwner)
+        |    abstract fun printRightNonCodeElements(element: JKNonCodeElementsListOwner)
+        |
+        """.trimMargin()
+        )
+
+        interfaceData.joinTo(this, separator = "\n\n") { (name, ext) ->
+            val nameWithoutPrefix = name.removePrefix("JK")
+            val argName = nameWithoutPrefix.decapitalize().safeVarName()
+            val arg = "$argName: $name"
+            val rawVisitSuffix = "Raw"
+            val generifyCall = if (name != "JKTreeElement") "= visit${ext!!.removePrefix("JK")}$rawVisitSuffix($argName)" else ""
+            val modifier = if (name == "JKTreeElement") "abstract" else "open"
+            """
+            |    final override fun visit$nameWithoutPrefix($arg) {
+            |        printLeftNonCodeElements($argName)
+            |        visit$nameWithoutPrefix$rawVisitSuffix($argName)
+            |        printRightNonCodeElements($argName)
+            |    }
+            |
+            |    $modifier fun visit$nameWithoutPrefix$rawVisitSuffix($arg) $generifyCall
+            """.trimMargin()
+        }
+        appendln()
+        appendln("}")
+    })
+}
+
+fun main() {
+    genVisitors(JK_TREE_FILES.flatMap { it.interfaceNames() }, "JKVisitor")
+}
+

nj2k/src/org/jetbrains/kotlin/nj2k/JKElementInfoStorage.kt

@@ -6,7 +6,8 @@
 package org.jetbrains.kotlin.nj2k
 
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
-
+import org.jetbrains.kotlin.utils.SmartList
+import kotlin.random.Random
 
 interface JKElementInfo
 
@@ -16,8 +17,23 @@ data class InternalSuperFunctionInfo(val label: JKElementInfoLabel) : SuperFunct
 
 data class FunctionInfo(val superFunctions: List<SuperFunctionInfo>) : JKElementInfo
 
-object UnknownNullability : JKElementInfo
-object UnknownMutability : JKElementInfo
+enum class JKTypeInfo(val unknownNullability: Boolean, val unknownMutability: Boolean) : JKElementInfo {
+    KNOWN_NULLABILITY_KNOWN_MUTABILITY(false, false),
+    UNKNOWN_NULLABILITY_KNOWN_MUTABILITY(true, false),
+    KNOWN_NULLABILITY_UNKNOWN_MUTABILITY(false, true),
+    UNKNOWN_NULLABILITY_UNKNOWN_MUTABILITY(true, true)
+    ;
+
+    companion object {
+        operator fun invoke(unknownNullability: Boolean, unknownMutability: Boolean) = when {
+            !unknownNullability && !unknownMutability -> KNOWN_NULLABILITY_KNOWN_MUTABILITY
+            unknownNullability && !unknownMutability -> UNKNOWN_NULLABILITY_KNOWN_MUTABILITY
+            !unknownNullability && unknownMutability -> KNOWN_NULLABILITY_UNKNOWN_MUTABILITY
+            else -> UNKNOWN_NULLABILITY_UNKNOWN_MUTABILITY
+        }
+    }
+}
+
 
 inline class JKElementInfoLabel(val label: String) {
     fun render(): String = "/*@@$label@@*/"
@@ -31,22 +47,18 @@ fun String.asLabel(): JKElementInfoLabel? =
     JKElementInfoLabel.LABEL_REGEX.matchEntire(this)?.groupValues?.getOrNull(1)?.let { JKElementInfoLabel(it) }
 
 class JKElementInfoStorage {
-    private val labelToInfo = mutableMapOf<JKElementInfoLabel, List<JKElementInfo>>()
+    private val labelToInfo = mutableMapOf<JKElementInfoLabel, MutableList<JKElementInfo>>()
     private val elementToLabel = mutableMapOf<Any, JKElementInfoLabel>()
 
     fun getOrCreateInfoForElement(element: Any): JKElementInfoLabel =
         elementToLabel.getOrPut(element) { JKElementInfoLabel(createRandomString()) }
 
-    fun getOrCreateInfoForLabel(label: JKElementInfoLabel): List<JKElementInfo> =
-        labelToInfo.getOrPut(label) { emptyList() }
-
     fun getInfoForLabel(label: JKElementInfoLabel): List<JKElementInfo>? =
         labelToInfo[label]
 
-
     fun addEntry(element: Any, info: JKElementInfo) {
         val label = elementToLabel.getOrPut(element) { JKElementInfoLabel(createRandomString()) }
-        labelToInfo[label] = labelToInfo[label].orEmpty() + info
+        labelToInfo.getOrPut(label) { SmartList() } += info
         elementToLabel[element] = label
     }
 
@@ -54,11 +66,8 @@ class JKElementInfoStorage {
         private val charPool = ('a'..'z').toList()
         private const val generatedStringLength = 6
 
-        private fun createRandomString(): String {
-            return (1..generatedStringLength)
-                .map { kotlin.random.Random.nextInt(0, charPool.size) }
-                .map(charPool::get)
-                .joinToString("")
+        private fun createRandomString() = (1..generatedStringLength).joinToString("") {
+            charPool[Random.nextInt(0, charPool.size)].toString()
         }
     }
 }

nj2k/src/org/jetbrains/kotlin/nj2k/conversions/AddElementsInfoConversion.kt

@@ -6,22 +6,22 @@
 package org.jetbrains.kotlin.nj2k.conversions
 
 import com.intellij.psi.PsiMethod
-import com.intellij.psi.impl.light.LightMethod
 import org.jetbrains.kotlin.asJava.elements.KtLightMethod
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptorIfAny
 import org.jetbrains.kotlin.idea.caches.resolve.util.getJavaMethodDescriptor
 import org.jetbrains.kotlin.j2k.ast.Nullability
 import org.jetbrains.kotlin.js.resolve.diagnostics.findPsi
-import org.jetbrains.kotlin.load.java.descriptors.JavaMethodDescriptor
 import org.jetbrains.kotlin.nj2k.*
 import org.jetbrains.kotlin.nj2k.symbols.JKUniverseMethodSymbol
 import org.jetbrains.kotlin.nj2k.tree.*
 import org.jetbrains.kotlin.nj2k.tree.impl.JKCapturedType
 import org.jetbrains.kotlin.nj2k.tree.impl.psi
+import org.jetbrains.kotlin.nj2k.types.JKParametrizedType
+import org.jetbrains.kotlin.nj2k.types.JKStarProjectionType
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
-class AddElementsInfoConversion(private val context: NewJ2kConverterContext) : RecursiveApplicableConversionBase() {
+class AddElementsInfoConversion(context: NewJ2kConverterContext) : RecursiveApplicableConversionBase(context) {
     override fun applyToElement(element: JKTreeElement): JKTreeElement {
         when (element) {
             is JKTypeElement -> addInfoForTypeElement(element)
@@ -33,14 +33,10 @@ class AddElementsInfoConversion(private val context: NewJ2kConverterContext) : R
 
     private fun addInfoForTypeElement(typeElement: JKTypeElement) {
         typeElement.type.forAllInnerTypes { type ->
-            if (type.nullability == Nullability.Default
-                || type.safeAs<JKCapturedType>()?.wildcardType is JKStarProjectionType
-            ) {
-                context.elementsInfoStorage.addEntry(type, UnknownNullability)
-            }
-            if (type.isCollectionType) {
-                context.elementsInfoStorage.addEntry(type, UnknownMutability)
-            }
+            val hasUnknownNullability =
+                type.nullability == Nullability.Default || type.safeAs<JKCapturedType>()?.wildcardType is JKStarProjectionType
+            val hasUnknownMutability = type.isCollectionType
+            context.elementsInfoStorage.addEntry(type, JKTypeInfo(hasUnknownNullability, hasUnknownMutability))
         }
     }
 
@@ -48,7 +44,7 @@ class AddElementsInfoConversion(private val context: NewJ2kConverterContext) : R
         val superMethods = function.superMethods() ?: return
         val superDescriptorsInfo = superMethods.map { superDescriptor ->
             val superPsi = superDescriptor.original.findPsi()
-            when (val symbol = context.symbolProvider.symbolsByPsi[superPsi]) {
+            when (val symbol = symbolProvider.symbolsByPsi[superPsi]) {
                 is JKUniverseMethodSymbol ->
                     InternalSuperFunctionInfo(context.elementsInfoStorage.getOrCreateInfoForElement(symbol.target))
                 else -> ExternalSuperFunctionInfo(superDescriptor)
@@ -59,8 +55,8 @@ class AddElementsInfoConversion(private val context: NewJ2kConverterContext) : R
 
     private fun JKMethod.superMethods(): Collection<FunctionDescriptor>? {
         val psiMethod = psi<PsiMethod>() ?: return null
-        psiMethod.getJavaMethodDescriptor()?.let { descriptor ->
-            return descriptor.overriddenDescriptors
+        psiMethod.getJavaMethodDescriptor()?.let {
+            return it.overriddenDescriptors
         }
         return psiMethod.findSuperMethods().mapNotNull { superMethod ->
             when (superMethod) {

nj2k/src/org/jetbrains/kotlin/nj2k/conversions/TypeMappingConversion.kt

@@ -112,6 +112,7 @@ class TypeMappingConversion(val context: NewJ2kConverterContext) : RecursiveAppl
 
     private fun JKClassSymbol.mapClassSymbol(typeElement: JKTypeElement?): JKClassSymbol {
         if (this is JKUniverseClassSymbol) return this
+        if (typeElement?.parentOfType<JKInheritanceInfo>() != null) return this
         val newFqName = kotlinCollectionClassName()
             ?: kotlinStandardType()
             ?: fqName

nj2k/testData/copyPaste/AddImports.expected.kt

@@ -1,5 +1,5 @@
 import java.io.File
 
-internal fun foo(file: File?): List<String> {
-    return emptyList()
+internal fun foo(file: File?): List<String?>? {
+    return emptyList<String>()
 }

nj2k/testData/copyPaste/AddImportsWithExplicitImports.expected.kt

@@ -1,7 +1,7 @@
 import java.io.File
 
 class C {
-    private fun memberFun(file: File?) {}
+    private fun memberFun(file: File) {}
 
     companion object {
         @JvmStatic

nj2k/testData/copyPaste/MethodWithNoAnnotation.expected.kt

@@ -1,5 +1,5 @@
 package to
 
-fun foo(): String {
+fun foo(): String? {
     return ""
 }

nj2k/testData/copyPaste/MethodWithOnlyOneAnnotation.expected.kt

@@ -1,6 +1,6 @@
 package to
 
 @SomeAnnotation
-fun foo(): String {
+fun foo(): String? {
     return ""
 }

nj2k/testData/copyPaste/SeveralMethodsSample.expected.kt

@@ -23,12 +23,12 @@ class A {
         return JetRefactoringUtil.formatPsiMethod(element as PsiMethod, true, false)
     }
 
-    protected fun getDimensionServiceKey(): String {
+    protected fun getDimensionServiceKey(): String? {
         return "#org.jetbrains.kotlin.idea.refactoring.safeDelete.KotlinOverridingDialog"
     }
 
-    fun getSelected(): ArrayList<UsageInfo> {
-        val result: ArrayList<UsageInfo> = ArrayList<UsageInfo?>()
+    fun getSelected(): ArrayList<UsageInfo>? {
+        val result: ArrayList<UsageInfo> = ArrayList<UsageInfo>()
         for (i in 0 until myChecked.length) {
             if (myChecked.get(i)) {
                 result.add(myOverridingMethods.get(i))

nj2k/testData/copyPastePlainText/AsExpression.expected.kt

@@ -3,5 +3,5 @@ import java.util.ArrayList
 
 
 fun foo() {
-    bar(ArrayList<String?>())
+    bar(ArrayList<String>())
 }

nj2k/testData/copyPastePlainText/AsExpressionBody.expected.kt

@@ -2,4 +2,4 @@
 import java.util.ArrayList
 
 
-fun foo() = ArrayList<String?>()
+fun foo() = ArrayList<String>()

nj2k/testData/copyPastePlainText/KT13529_1.expected.kt

@@ -3,5 +3,5 @@ import java.util.ArrayList
 
 
 fun foo() {
-    bar(/*comment*/ArrayList<String?>())
+    bar(/*comment*/ArrayList<String>())
 }

nj2k/testData/copyPastePlainText/PostProcessing.expected.kt

@@ -5,7 +5,7 @@ import java.util.ArrayList
 
 
 class JavaClass {
-    internal fun foo(file: File?, target: List<String?>?) {
+    internal fun foo(file: File?, target: MutableList<String>?) {
         val list = ArrayList<String>()
         if (file != null) {
             list.add(file.name)

nj2k/testData/inference/common/forLoop.kt

@@ -7,4 +7,4 @@ fun test() {
 
 //T0 <: T1 due to 'INITIALIZER'
 //T2 <: T4 due to 'INITIALIZER'
-//T3 <: T1 due to 'ASSIGNMENT'
+//T1 <: T3 due to 'ASSIGNMENT'

nj2k/testData/inference/common/newExpression.kt

@@ -0,0 +1,5 @@
+class Test {
+    val x: /*T2@*/List</*T1@*/Int> = ArrayList</*T0@*/Int>()/*ArrayList<T0@Int>*/
+}
+
+//T1 := T0 due to 'INITIALIZER'

nj2k/testData/inference/mutability/IteratorMutableCalls.kt

@@ -0,0 +1,8 @@
+fun a(
+    l0: /*T1@*/MutableIterator</*T0@*/Int>
+) {
+    l0/*T1@MutableIterator<T0@Int>*/.remove()
+}
+
+//T0 <: T0 due to 'RECEIVER_PARAMETER'
+//T1 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/arrayList.kt

@@ -0,0 +1,7 @@
+import java.util.ArrayList
+
+fun a() {
+    val list: /*T2@*/List</*T1@*/Int> = ArrayList</*T0@*/Int>()/*ArrayList<T0@Int>*/
+}
+
+//T1 := T0 due to 'INITIALIZER'

nj2k/testData/inference/mutability/collectionMutableCalls.kt

@@ -0,0 +1,30 @@
+fun a(
+        l0: /*T1@*/MutableCollection</*T0@*/Int>,
+        l1: /*T3@*/MutableCollection</*T2@*/Int>,
+        l2: /*T5@*/MutableCollection</*T4@*/Int>,
+        l3: /*T7@*/MutableCollection</*T6@*/Int>,
+        l4: /*T9@*/MutableCollection</*T8@*/Int>
+) {
+    l0/*T1@MutableCollection<T0@Int>*/.add(1/*LIT*/)
+    l1/*T3@MutableCollection<T2@Int>*/.addAll(l1/*T3@MutableCollection<T2@Int>*/)
+    l2/*T5@MutableCollection<T4@Int>*/.clear()
+    l3/*T7@MutableCollection<T6@Int>*/.removeAll(l1/*T3@MutableCollection<T2@Int>*/)
+    l4/*T9@MutableCollection<T8@Int>*/.retainAll(l1/*T3@MutableCollection<T2@Int>*/)
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T1 := LOWER due to 'USE_AS_RECEIVER'
+//T2 := T2 due to 'RECEIVER_PARAMETER'
+//T2 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T3 := LOWER due to 'USE_AS_RECEIVER'
+//T4 := T4 due to 'RECEIVER_PARAMETER'
+//T5 := LOWER due to 'USE_AS_RECEIVER'
+//T6 := T6 due to 'RECEIVER_PARAMETER'
+//T6 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T7 := LOWER due to 'USE_AS_RECEIVER'
+//T8 := T8 due to 'RECEIVER_PARAMETER'
+//T8 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T9 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/covariance.kt

@@ -0,0 +1,8 @@
+class Nya {
+    private val hashMap: /*T6@*/Map</*T3@*/String, /*T5@*/List</*T4@*/Int>> =
+            HashMap</*T0@*/String, /*T2@*/List</*T1@*/Int>>()/*HashMap<T0@String, T2@MutableList<T1@Int>>*/
+}
+
+//T3 := T0 due to 'INITIALIZER'
+//T4 := T1 due to 'INITIALIZER'
+//T5 := T2 due to 'INITIALIZER'

nj2k/testData/inference/mutability/iteratorCall.kt

@@ -0,0 +1,10 @@
+fun a(l0: /*T1@*/MutableList</*T0@*/Int>) {
+    val iterator: /*T3@*/MutableIterator</*T2@*/Int> = l0/*T1@MutableList<T0@Int>*/.iterator()/*T1@MutableList<T0@Int>*/
+    iterator/*T3@MutableIterator<T2@Int>*/.remove()
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T2 := T0 due to 'INITIALIZER'
+//T1 <: T3 due to 'INITIALIZER'
+//T2 <: T2 due to 'RECEIVER_PARAMETER'
+//T3 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/list.kt

@@ -0,0 +1,4 @@
+class A {
+    val l: /*T1@*/List</*T0@*/Int>
+}
+

nj2k/testData/inference/mutability/listIteratorMutableCalls.kt

@@ -0,0 +1,16 @@
+fun a(
+        l0: /*T1@*/MutableListIterator</*T0@*/Int>,
+        l1: /*T3@*/MutableListIterator</*T2@*/Int>,
+        l2: /*T5@*/MutableListIterator</*T4@*/Int>
+) {
+    l0/*T1@MutableListIterator<T0@Int>*/.add(1/*LIT*/)
+    l1/*T3@MutableListIterator<T2@Int>*/.remove()
+    l2/*T5@MutableListIterator<T4@Int>*/.set(1/*LIT*/)
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T1 := LOWER due to 'USE_AS_RECEIVER'
+//T2 := T2 due to 'RECEIVER_PARAMETER'
+//T3 := LOWER due to 'USE_AS_RECEIVER'
+//T4 := T4 due to 'RECEIVER_PARAMETER'
+//T5 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/listMutableCalls.kt

@@ -0,0 +1,46 @@
+fun a(
+        l0: /*T1@*/MutableList</*T0@*/Int>,
+        l1: /*T3@*/MutableList</*T2@*/Int>,
+        l2: /*T5@*/MutableList</*T4@*/Int>,
+        l3: /*T7@*/MutableList</*T6@*/Int>,
+        l4: /*T9@*/MutableList</*T8@*/Int>,
+        l5: /*T11@*/MutableList</*T10@*/Int>,
+        l6: /*T13@*/MutableList</*T12@*/Int>,
+        l7: /*T15@*/MutableList</*T14@*/Int>
+) {
+    l0/*T1@MutableList<T0@Int>*/.add(1/*LIT*/)
+    l1/*T3@MutableList<T2@Int>*/.addAll(1/*LIT*/, l1/*T3@MutableList<T2@Int>*/)
+    l2/*T5@MutableList<T4@Int>*/.addAll(l1/*T3@MutableList<T2@Int>*/)
+    l3/*T7@MutableList<T6@Int>*/.clear()
+    l4/*T9@MutableList<T8@Int>*/.remove(1/*LIT*/)
+    l5/*T11@MutableList<T10@Int>*/.removeAll(l1/*T3@MutableList<T2@Int>*/)
+    l5/*T11@MutableList<T10@Int>*/.removeAt(0/*LIT*/)
+    l6/*T13@MutableList<T12@Int>*/.retainAll(l1/*T3@MutableList<T2@Int>*/)
+    l7/*T15@MutableList<T14@Int>*/.set(0/*LIT*/, 0/*LIT*/)
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T1 := LOWER due to 'USE_AS_RECEIVER'
+//T2 := T2 due to 'RECEIVER_PARAMETER'
+//T2 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T3 := LOWER due to 'USE_AS_RECEIVER'
+//T4 := T4 due to 'RECEIVER_PARAMETER'
+//T4 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T5 := LOWER due to 'USE_AS_RECEIVER'
+//T6 := T6 due to 'RECEIVER_PARAMETER'
+//T7 := LOWER due to 'USE_AS_RECEIVER'
+//T8 := T8 due to 'RECEIVER_PARAMETER'
+//T9 := LOWER due to 'USE_AS_RECEIVER'
+//T10 := T10 due to 'RECEIVER_PARAMETER'
+//T10 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T11 := LOWER due to 'USE_AS_RECEIVER'
+//T10 := T10 due to 'RECEIVER_PARAMETER'
+//T12 := T12 due to 'RECEIVER_PARAMETER'
+//T12 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T13 := LOWER due to 'USE_AS_RECEIVER'
+//T14 := T14 due to 'RECEIVER_PARAMETER'
+//T15 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/listOfListsForEach.kt

@@ -0,0 +1,15 @@
+import java.util.ArrayList
+
+fun test() {
+    val list: /*T4@*/List</*T3@*/MutableList</*T2@*/Int>> = ArrayList</*T1@*/MutableList</*T0@*/Int>>()/*ArrayList<T1@MutableList<T0@Int>>*/
+    for(l: /*T6@*/MutableList</*T5@*/Int> in list/*T4@MutableList<T3@MutableList<T2@Int>>*/) {
+        l/*T6@MutableList<T5@Int>*/.add(42/*LIT*/)
+    }
+}
+
+//T2 := T0 due to 'INITIALIZER'
+//T3 := T1 due to 'INITIALIZER'
+//T5 := T5 due to 'RECEIVER_PARAMETER'
+//T6 := LOWER due to 'USE_AS_RECEIVER'
+//T5 := T2 due to 'ASSIGNMENT'
+//T3 <: T6 due to 'ASSIGNMENT'

nj2k/testData/inference/mutability/listOfMutableList.kt

@@ -0,0 +1,14 @@
+import java.util.ArrayList
+
+fun a() {
+    val list: /*T4@*/List</*T3@*/MutableList</*T2@*/Int>> = ArrayList</*T1@*/MutableList</*T0@*/Int>>()/*ArrayList<T1@MutableList<T0@Int>>*/
+    list/*T4@MutableList<T3@MutableList<T2@Int>>*/.get(0/*LIT*/)/*T3@MutableList<T2@Int>*/.add(1/*LIT*/)
+}
+
+//T2 := T0 due to 'INITIALIZER'
+//T3 := T1 due to 'INITIALIZER'
+//T2 := T2 due to 'RECEIVER_PARAMETER'
+//T3 := T3 due to 'RECEIVER_PARAMETER'
+//T4 <: UPPER due to 'RECEIVER_PARAMETER'
+//T2 := T2 due to 'RECEIVER_PARAMETER'
+//T3 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/mapEntryMutableCalls.kt

@@ -0,0 +1,9 @@
+fun a(
+    l0: /*T2@*/MutableMap.MutableEntry</*T0@*/Int, /*T1@*/String>
+) {
+    l0/*T2@MutableEntry<T0@Int, T1@String>*/.setValue(1/*LIT*/, "nya")
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T1 := T1 due to 'RECEIVER_PARAMETER'
+//T2 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/mapMutableCalls.kt

@@ -0,0 +1,27 @@
+fun a(
+        l0: /*T2@*/MutableMap</*T0@*/Int, /*T1@*/String>,
+        l1: /*T5@*/MutableMap</*T3@*/Int, /*T4@*/String>,
+        l2: /*T8@*/MutableMap</*T6@*/Int, /*T7@*/String>,
+        l3: /*T11@*/MutableMap</*T9@*/Int, /*T10@*/String>
+) {
+    l0/*T2@MutableMap<T0@Int, T1@String>*/.put(1)
+    l1/*T5@MutableMap<T3@Int, T4@String>*/.remove(1/*LIT*/, l1)
+    l2/*T8@MutableMap<T6@Int, T7@String>*/.putAll(l1/*T5@MutableMap<T3@Int, T4@String>*/)
+    l3/*T11@MutableMap<T9@Int, T10@String>*/.clear(1)
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T1 := T1 due to 'RECEIVER_PARAMETER'
+//T2 := LOWER due to 'USE_AS_RECEIVER'
+//T3 := T3 due to 'RECEIVER_PARAMETER'
+//T4 := T4 due to 'RECEIVER_PARAMETER'
+//T5 := LOWER due to 'USE_AS_RECEIVER'
+//T6 := T6 due to 'RECEIVER_PARAMETER'
+//T7 := T7 due to 'RECEIVER_PARAMETER'
+//T6 := T3 due to 'PARAMETER'
+//T7 := T4 due to 'PARAMETER'
+//T5 <: UPPER due to 'PARAMETER'
+//T8 := LOWER due to 'USE_AS_RECEIVER'
+//T9 := T9 due to 'RECEIVER_PARAMETER'
+//T10 := T10 due to 'RECEIVER_PARAMETER'
+//T11 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/mutability/setMutableCalls.kt

@@ -0,0 +1,30 @@
+fun a(
+        l0: /*T1@*/MutableSet</*T0@*/Int>,
+        l1: /*T3@*/MutableSet</*T2@*/Int>,
+        l2: /*T5@*/MutableSet</*T4@*/Int>,
+        l3: /*T7@*/MutableSet</*T6@*/Int>,
+        l4: /*T9@*/MutableSet</*T8@*/Int>
+) {
+    l0/*T1@MutableSet<T0@Int>*/.add(1/*LIT*/)
+    l1/*T3@MutableSet<T2@Int>*/.addAll(l1/*T3@MutableSet<T2@Int>*/)
+    l2/*T5@MutableSet<T4@Int>*/.clear()
+    l3/*T7@MutableSet<T6@Int>*/.removeAll(l1/*T3@MutableSet<T2@Int>*/)
+    l4/*T9@MutableSet<T8@Int>*/.retainAll(l1/*T3@MutableSet<T2@Int>*/)
+}
+
+//T0 := T0 due to 'RECEIVER_PARAMETER'
+//T1 := LOWER due to 'USE_AS_RECEIVER'
+//T2 := T2 due to 'RECEIVER_PARAMETER'
+//T2 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T3 := LOWER due to 'USE_AS_RECEIVER'
+//T4 := T4 due to 'RECEIVER_PARAMETER'
+//T5 := LOWER due to 'USE_AS_RECEIVER'
+//T6 := T6 due to 'RECEIVER_PARAMETER'
+//T6 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T7 := LOWER due to 'USE_AS_RECEIVER'
+//T8 := T8 due to 'RECEIVER_PARAMETER'
+//T8 := T2 due to 'PARAMETER'
+//T3 <: UPPER due to 'PARAMETER'
+//T9 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/nullability/loopIterator.kt

@@ -4,5 +4,5 @@ fun test(a: /*T1@*/List</*T0@*/Int?>) {
     }
 }
 
-//T2 <: T0 due to 'ASSIGNMENT'
+//T0 <: T2 due to 'ASSIGNMENT'
 //T1 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/inference/nullability/loops.kt

@@ -1,4 +1,4 @@
-fun bar(map: /*T2@*/HashMap</*T0@*/String?, /*T1@*/Int>, list1: /*T4@*/List</*T3@*/Int?>, list2: /*T6@*/List</*T5@*/String?>) {
+fun bar(map: /*T2@*/HashMap</*T0@*/String?, /*T1@*/Int>, list1: /*T4@*/List</*T3@*/Int>, list2: /*T6@*/List</*T5@*/String?>) {
     for (entry: /*T9@*/MutableMap.MutableEntry</*T7@*/String?, /*T8@*/Int> in map/*T2@HashMap<T0@String, T1@Int>*/.entries/*MutableSet<MutableEntry<T0@String, T1@Int>>*/) {
         val value: /*T10@*/Int = entry/*T9@MutableEntry<T7@String, T8@Int>*/.value/*T8@Int*/
         if (entry/*T9@MutableEntry<T7@String, T8@Int>*/.key/*T7@String*/ == null/*LIT*/) {
@@ -21,11 +21,11 @@ fun bar(map: /*T2@*/HashMap</*T0@*/String?, /*T1@*/Int>, list1: /*T4@*/List</*T3
 //T9 := LOWER due to 'USE_AS_RECEIVER'
 //T7 := UPPER due to 'COMPARE_WITH_NULL'
 //T10 := LOWER due to 'USE_AS_RECEIVER'
-//T0 := T7 due to 'ASSIGNMENT'
-//T1 := T8 due to 'ASSIGNMENT'
+//T7 := T0 due to 'ASSIGNMENT'
+//T8 := T1 due to 'ASSIGNMENT'
 //T11 := LOWER due to 'USE_AS_RECEIVER'
-//T11 <: T3 due to 'ASSIGNMENT'
+//T3 <: T11 due to 'ASSIGNMENT'
 //T4 := LOWER due to 'USE_AS_RECEIVER'
 //T12 := UPPER due to 'COMPARE_WITH_NULL'
-//T12 <: T5 due to 'ASSIGNMENT'
+//T5 <: T12 due to 'ASSIGNMENT'
 //T6 := LOWER due to 'USE_AS_RECEIVER'

nj2k/testData/newJ2k/detectProperties/Overrides.kt

@@ -18,19 +18,19 @@ internal open class B {
     open val fromB1: String
         get() = ""
 
-    open var fromB2: String
+    open var fromB2: String?
         get() = ""
         set(value) {}
 
-    open var fromB3: String
+    open var fromB3: String?
         get() = ""
         set(value) {}
 
-    open var fromB4: String
+    open var fromB4: String?
         get() = ""
         set(value) {}
 
-    open fun setFromB5(value: String) {}
+    open fun setFromB5(value: String?) {}
 }
 
 internal abstract class C(override val something1: Int) : B(), I {
@@ -59,19 +59,19 @@ internal abstract class C(override val something1: Int) : B(), I {
     override val fromB1: String
         get() = super.fromB1
 
-    override var fromB2: String
+    override var fromB2: String?
         get() = super.fromB2
         set(value) {
             super.fromB2 = value
         }
 
-    override var fromB3: String
+    override var fromB3: String?
         get() = super.fromB3
         set(fromB3) {
             super.fromB3 = fromB3
         }
 
-    override var fromB4: String
+    override var fromB4: String?
         get() = super.fromB4
         set(value) {
             super.fromB4 = value
@@ -81,7 +81,8 @@ internal abstract class C(override val something1: Int) : B(), I {
         return ""
     }
 
-    override fun setFromB5(value: String) {
+    override fun setFromB5(value: String?) {
         super.setFromB5(value)
     }
+
 }

nj2k/testData/newJ2k/detectProperties/commentInInitStatement.java

@@ -0,0 +1,8 @@
+public class Nya {
+    private int i;
+
+    public Nya(int i) {
+        /*comment before*/
+        this/*1*/./*2*/i/*3*/ = /*4*/i /* comment after*/; // and after again
+    }
+}

nj2k/testData/newJ2k/detectProperties/commentInInitStatement.kt

@@ -0,0 +1 @@
+class Nya /*comment before*/(/*1*//*3*/ /*4*/private val i: Int)

nj2k/testData/newJ2k/foreachStatement/nullableIterable.kt

@@ -1,5 +1,5 @@
 internal class A {
-    var list: List<String?>? = null
+    var list: List<String>? = null
     fun foo() {
         for (e in list!!) {
             println(e)

nj2k/testData/newJ2k/issues/kt-15791.kt

@@ -3,6 +3,6 @@ import java.util.ArrayList
 internal object A {
     @JvmStatic
     fun main(args: Array<String>) {
-        List::class.java.isAssignableFrom(ArrayList::class.java)
+        MutableList::class.java.isAssignableFrom(ArrayList::class.java)
     }
 }

nj2k/testData/newJ2k/issues/kt-5294.kt

@@ -1,4 +1,5 @@
-internal class X(private val list: MutableList<Y>) {
+internal class X(private val list: List<Y>) {
 
     internal inner class Y
+
 }

nj2k/testData/newJ2k/methodCallExpression/specialBuiltinMembers.kt

@@ -1,4 +1,3 @@
-// ERROR: Operator call corresponds to a dot-qualified call 'value.plus(1)' which is not allowed on a nullable receiver 'value'.
 import java.util.HashMap
 
 internal enum class E { A, B, C }
@@ -15,7 +14,7 @@ internal class A {
         val i = map.entries.iterator().next().key + 1
     }
 
-    fun bar(list: MutableList<String?>, map: HashMap<String?, Int?>) {
+    fun bar(list: MutableList<String?>, map: HashMap<String, Int>) {
         val c = "a"[0]
         val b = 10.toByte()
         val i = 10.1.toInt()

nj2k/testData/newJ2k/mutableCollections/implementMutableIterator.java

@@ -0,0 +1,17 @@
+import java.util.Iterator;
+
+public class TestMutableIterator implements Iterator<String> {
+    @Override
+    public boolean hasNext() {
+        return false;
+    }
+
+    @Override
+    public String next() {
+        return null;
+    }
+
+    @Override
+    public void remove() {
+    }
+}

nj2k/testData/newJ2k/mutableCollections/listOfMutableList.java

@@ -0,0 +1,11 @@
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+public class Test {
+    List<List<Integer>> list = new ArrayList<>();
+
+    public void test() {
+        list.get(0).add(1)
+    }
+}

nj2k/testData/newJ2k/mutableCollections/listOfMutableList.kt

@@ -0,0 +1,8 @@
+import java.util.ArrayList
+
+class Test {
+    internal var list: List<List<Int>> = ArrayList()
+    fun test() {
+        list[0].add(1)
+    }
+}

nj2k/testData/newJ2k/mutableCollections/mutableListInOtherClass.java

@@ -0,0 +1,12 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class Owner {
+    public List<String> list = new ArrayList<>();
+}
+
+public class Updater {
+    public void update(Owner owner) {
+        owner.list.add("");
+    }
+}

nj2k/testData/newJ2k/mutableCollections/mutableListInOtherClass.kt

@@ -0,0 +1,11 @@
+import java.util.ArrayList
+
+class Owner {
+    var list: MutableList<String> = ArrayList()
+}
+
+class Updater {
+    fun update(owner: Owner) {
+        owner.list.add("")
+    }
+}

nj2k/tests/org/jetbrains/kotlin/nj2k/NewJavaToKotlinConverterSingleFileTestGenerated.java

@@ -1376,6 +1376,11 @@ public class NewJavaToKotlinConverterSingleFileTestGenerated extends AbstractNew
             runTest("nj2k/testData/newJ2k/detectProperties/CannotDropOnlySetter.java");
         }
 
+        @TestMetadata("commentInInitStatement.java")
+        public void testCommentInInitStatement() throws Exception {
+            runTest("nj2k/testData/newJ2k/detectProperties/commentInInitStatement.java");
+        }
+
         @TestMetadata("Comments.java")
         public void testComments() throws Exception {
             runTest("nj2k/testData/newJ2k/detectProperties/Comments.java");
@@ -3628,6 +3633,16 @@ public class NewJavaToKotlinConverterSingleFileTestGenerated extends AbstractNew
             runTest("nj2k/testData/newJ2k/mutableCollections/Iterator2.java");
         }
 
+        @TestMetadata("listOfMutableList.java")
+        public void testListOfMutableList() throws Exception {
+            runTest("nj2k/testData/newJ2k/mutableCollections/listOfMutableList.java");
+        }
+
+        @TestMetadata("mutableListInOtherClass.java")
+        public void testMutableListInOtherClass() throws Exception {
+            runTest("nj2k/testData/newJ2k/mutableCollections/mutableListInOtherClass.java");
+        }
+
         @TestMetadata("Overrides.java")
         public void testOverrides() throws Exception {
             runTest("nj2k/testData/newJ2k/mutableCollections/Overrides.java");

nj2k/tests/org/jetbrains/kotlin/nj2k/inference/common/AbstractCommonConstraintCollectorTest.kt

@@ -17,7 +17,7 @@ abstract class AbstractCommonConstraintCollectorTest : AbstractConstraintCollect
     override fun createInferenceFacade(resolutionFacade: ResolutionFacade): InferenceFacade =
         InferenceFacade(
             object : ContextCollector(resolutionFacade) {
-                override fun ClassReference.getState(typeElement: KtTypeElement?): State? =
+                override fun ClassReference.getState(typeElement: KtTypeElement?): State =
                     State.UNKNOWN
             },
             ConstraintsCollectorAggregator(

nj2k/tests/org/jetbrains/kotlin/nj2k/inference/common/CommonConstraintCollectorTestGenerated.java

@@ -134,6 +134,11 @@ public class CommonConstraintCollectorTestGenerated extends AbstractCommonConstr
         runTest("nj2k/testData/inference/common/memberCall.kt");
     }
 
+    @TestMetadata("newExpression.kt")
+    public void testNewExpression() throws Exception {
+        runTest("nj2k/testData/inference/common/newExpression.kt");
+    }
+
     @TestMetadata("returnFromLambda.kt")
     public void testReturnFromLambda() throws Exception {
         runTest("nj2k/testData/inference/common/returnFromLambda.kt");

nj2k/tests/org/jetbrains/kotlin/nj2k/inference/mutability/AbstractMutabilityInferenceTest.kt

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability
+
+import com.intellij.openapi.application.runWriteAction
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.core.ShortenReferences
+import org.jetbrains.kotlin.idea.formatter.commitAndUnblockDocument
+import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
+import org.jetbrains.kotlin.nj2k.descriptorByFileDirective
+import org.jetbrains.kotlin.nj2k.inference.AbstractConstraintCollectorTest
+import org.jetbrains.kotlin.nj2k.inference.common.*
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.CallExpressionConstraintCollector
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.CommonConstraintsCollector
+import org.jetbrains.kotlin.nj2k.inference.common.collectors.FunctionConstraintsCollector
+import org.jetbrains.kotlin.psi.KtConstructorCalleeExpression
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtTypeElement
+import org.jetbrains.kotlin.psi.KtTypeReference
+import org.jetbrains.kotlin.psi.psiUtil.collectDescendantsOfType
+import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
+import java.io.File
+
+abstract class AbstractMutabilityInferenceTest : AbstractConstraintCollectorTest() {
+    override fun createInferenceFacade(resolutionFacade: ResolutionFacade): InferenceFacade {
+        val typeEnhancer = MutabilityBoundTypeEnhancer()
+        return InferenceFacade(
+            object : ContextCollector(resolutionFacade) {
+                override fun ClassReference.getState(typeElement: KtTypeElement?) =
+                    when (descriptor?.fqNameOrNull()) {
+                        in MutabilityStateUpdater.mutableToImmutable -> State.UNKNOWN
+                        in MutabilityStateUpdater.immutableToMutable -> State.UNKNOWN
+                        else -> State.UNUSED
+                    }
+            },
+            ConstraintsCollectorAggregator(
+                resolutionFacade,
+                MutabilityConstraintBoundProvider(),
+                listOf(
+                    CommonConstraintsCollector(),
+                    CallExpressionConstraintCollector(),
+                    FunctionConstraintsCollector(ResolveSuperFunctionsProvider(resolutionFacade)),
+                    MutabilityConstraintsCollector()
+                )
+            ),
+            MutabilityBoundTypeCalculator(resolutionFacade, typeEnhancer),
+            MutabilityStateUpdater(),
+            MutabilityDefaultStateProvider(),
+            renderDebugTypes = true,
+            printDebugConstraints = true
+        )
+    }
+
+    override fun KtFile.afterInference(): Unit = runWriteAction {
+        commitAndUnblockDocument()
+        ShortenReferences.DEFAULT.process(this)
+    }
+
+    override fun KtFile.prepareFile() = runWriteAction {
+        fun KtTypeReference.updateMutability() {
+            MutabilityStateUpdater.changeState(
+                typeElement ?: return,
+                analyze()[BindingContext.TYPE, this]!!,
+                toMutable = true
+            )
+            for (typeArgument in typeElement!!.typeArgumentsAsTypes) {
+                typeArgument.updateMutability()
+            }
+        }
+        for (typeReference in collectDescendantsOfType<KtTypeReference>()) {
+            if (typeReference.parent is KtConstructorCalleeExpression) continue
+            typeReference.updateMutability()
+        }
+        deleteComments()
+    }
+
+    override fun getProjectDescriptor() =
+        descriptorByFileDirective(File(testDataPath, fileName()), isAllFilesPresentInTest())
+}

nj2k/tests/org/jetbrains/kotlin/nj2k/inference/mutability/MutabilityInferenceTestGenerated.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.nj2k.inference.mutability;
+
+import com.intellij.testFramework.TestDataPath;
+import org.jetbrains.kotlin.test.JUnit3RunnerWithInners;
+import org.jetbrains.kotlin.test.KotlinTestUtils;
+import org.jetbrains.kotlin.test.TargetBackend;
+import org.jetbrains.kotlin.test.TestMetadata;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.util.regex.Pattern;
+
+/** This class is generated by {@link org.jetbrains.kotlin.generators.tests.TestsPackage}. DO NOT MODIFY MANUALLY */
+@SuppressWarnings("all")
+@TestMetadata("nj2k/testData/inference/mutability")
+@TestDataPath("$PROJECT_ROOT")
+@RunWith(JUnit3RunnerWithInners.class)
+public class MutabilityInferenceTestGenerated extends AbstractMutabilityInferenceTest {
+    private void runTest(String testDataFilePath) throws Exception {
+        KotlinTestUtils.runTest(this::doTest, TargetBackend.ANY, testDataFilePath);
+    }
+
+    public void testAllFilesPresentInMutability() throws Exception {
+        KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("nj2k/testData/inference/mutability"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
+    }
+
+    @TestMetadata("arrayList.kt")
+    public void testArrayList() throws Exception {
+        runTest("nj2k/testData/inference/mutability/arrayList.kt");
+    }
+
+    @TestMetadata("collectionMutableCalls.kt")
+    public void testCollectionMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/collectionMutableCalls.kt");
+    }
+
+    @TestMetadata("covariance.kt")
+    public void testCovariance() throws Exception {
+        runTest("nj2k/testData/inference/mutability/covariance.kt");
+    }
+
+    @TestMetadata("iteratorCall.kt")
+    public void testIteratorCall() throws Exception {
+        runTest("nj2k/testData/inference/mutability/iteratorCall.kt");
+    }
+
+    @TestMetadata("IteratorMutableCalls.kt")
+    public void testIteratorMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/IteratorMutableCalls.kt");
+    }
+
+    @TestMetadata("list.kt")
+    public void testList() throws Exception {
+        runTest("nj2k/testData/inference/mutability/list.kt");
+    }
+
+    @TestMetadata("listIteratorMutableCalls.kt")
+    public void testListIteratorMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/listIteratorMutableCalls.kt");
+    }
+
+    @TestMetadata("listMutableCalls.kt")
+    public void testListMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/listMutableCalls.kt");
+    }
+
+    @TestMetadata("listOfListsForEach.kt")
+    public void testListOfListsForEach() throws Exception {
+        runTest("nj2k/testData/inference/mutability/listOfListsForEach.kt");
+    }
+
+    @TestMetadata("listOfMutableList.kt")
+    public void testListOfMutableList() throws Exception {
+        runTest("nj2k/testData/inference/mutability/listOfMutableList.kt");
+    }
+
+    @TestMetadata("mapEntryMutableCalls.kt")
+    public void testMapEntryMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/mapEntryMutableCalls.kt");
+    }
+
+    @TestMetadata("mapMutableCalls.kt")
+    public void testMapMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/mapMutableCalls.kt");
+    }
+
+    @TestMetadata("setMutableCalls.kt")
+    public void testSetMutableCalls() throws Exception {
+        runTest("nj2k/testData/inference/mutability/setMutableCalls.kt");
+    }
+}

nj2k/tests/org/jetbrains/kotlin/nj2k/inference/nullability/AbstractNullabilityInferenceTest.kt

@@ -26,7 +26,7 @@ abstract class AbstractNullabilityInferenceTest : AbstractConstraintCollectorTes
         val typeEnhancer = NullabilityBoundTypeEnhancer(resolutionFacade)
         return InferenceFacade(
             object : ContextCollector(resolutionFacade) {
-                override fun ClassReference.getState(typeElement: KtTypeElement?): State? =
+                override fun ClassReference.getState(typeElement: KtTypeElement?): State =
                     State.UNKNOWN
             },
             ConstraintsCollectorAggregator(