Eliminate a set of warnings, mostly nullability ones

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/repl/GenericReplCompilingEvaluator.kt

@@ -63,10 +63,8 @@ class GenericReplCompilingEvaluator(val compiler: ReplCompiler,
                         is ReplEvalResult.ValueResult,
                         is ReplEvalResult.UnitResult ->
                             result
-                        else -> throw IllegalStateException("Unknown evaluator result type $compiled")
                     }
                 }
-                else -> throw IllegalStateException("Unknown compiler result type $compiled")
             }
         }
     }

compiler/daemon/daemon-client/src/org/jetbrains/kotlin/daemon/client/KotlinCompilerClient.kt

@@ -325,7 +325,7 @@ object KotlinCompilerClient {
                 if (err != null) {
                     reportingTargets.report(DaemonReportCategory.INFO,
                                             (if (attempts >= DAEMON_CONNECT_CYCLE_ATTEMPTS || !autostart) "no more retries on: " else "retrying($attempts) on: ")
-                                            + err?.toString())
+                                            + err.toString())
                 }
 
                 if (attempts++ > DAEMON_CONNECT_CYCLE_ATTEMPTS || !autostart) {

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/ExternalFunChecker.kt

@@ -51,8 +51,7 @@ class ExternalFunChecker : SimpleDeclarationChecker {
         if (DescriptorUtils.isInterface(descriptor.containingDeclaration)) {
             diagnosticHolder.report(ErrorsJvm.EXTERNAL_DECLARATION_IN_INTERFACE.on(declaration))
         }
-        else if (descriptor is CallableMemberDescriptor &&
+        else if (descriptor.modality == Modality.ABSTRACT) {
-                 descriptor.modality == Modality.ABSTRACT) {
             if (declaration is KtPropertyAccessor) {
                 diagnosticHolder.report(ErrorsJvm.EXTERNAL_DECLARATION_CANNOT_BE_ABSTRACT.on(declaration.property))
             }

compiler/frontend/src/org/jetbrains/kotlin/psi/KtCodeFragment.kt

@@ -163,7 +163,7 @@ abstract class KtCodeFragment(
     }
 
     fun getContextContainingFile(): KtFile? {
-        return (getOriginalContext() as? KtElement)?.containingKtFile
+        return getOriginalContext()?.containingKtFile
     }
 
     fun getOriginalContext(): KtElement? {

compiler/frontend/src/org/jetbrains/kotlin/psi/KtEnumEntrySuperclassReferenceExpression.kt

@@ -40,7 +40,7 @@ class KtEnumEntrySuperclassReferenceExpression :
             get() = calcReferencedElement()!!
 
     private fun calcReferencedElement(): KtClass? {
-        val owner = this.getStrictParentOfType<KtEnumEntry>() as? KtEnumEntry
+        val owner = this.getStrictParentOfType<KtEnumEntry>()
         return owner?.parent?.parent as? KtClass
     }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ConstModifierChecker.kt

@@ -65,7 +65,7 @@ object ConstModifierChecker : SimpleDeclarationChecker {
             return Errors.CONST_VAL_WITH_DELEGATE.on(declaration.delegate!!).nonApplicable()
         }
 
-        if (descriptor is PropertyDescriptor && !descriptor.getter!!.isDefault) {
+        if (!descriptor.getter!!.isDefault) {
             return Errors.CONST_VAL_WITH_GETTER.on(declaration.getter!!).nonApplicable()
         }
 

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/LabelResolver.kt

@@ -90,6 +90,7 @@ object LabelResolver {
 
         if (parent is KtValueArgument) {
             // f ({}) or f(p = {}) or f (fun () {})
+            // NB: parent of KtElement is really nullable!!!
             val argList = parent.parent ?: return null
             val call = argList.parent
             if (call is KtCallExpression) {

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/IncrementalJvmCompilerRunner.kt

@@ -272,7 +272,6 @@ class IncrementalJvmCompilerRunner(
                 // there is no point in updating annotation file since all files will be compiled anyway
                 kaptAnnotationsFileUpdater = null
             }
-            else -> throw IllegalStateException("Unknown CompilationMode ${compilationMode::class.java}")
         }
 
         val currentBuildInfo = BuildInfo(startTS = System.currentTimeMillis())

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/DefaultArgumentStubGenerator.kt

@@ -195,7 +195,7 @@ private fun Scope.createTemporaryVariable(symbol: IrVariableSymbol, initializer:
         }
 
 private fun getDefaultParameterExpressionBody(irFunction: IrFunction, valueParameter: ValueParameterDescriptor):IrExpressionBody {
-    return irFunction.getDefault(valueParameter) as? IrExpressionBody ?: TODO("FIXME!!!")
+    return irFunction.getDefault(valueParameter) ?: TODO("FIXME!!!")
 }
 
 private fun maskParameterDescriptor(function: IrFunction, number: Int) =

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/CompareTo.kt

@@ -23,7 +23,6 @@ import org.jetbrains.kotlin.codegen.AsmUtil.comparisonOperandType
 import org.jetbrains.kotlin.codegen.AsmUtil.isPrimitive
 import org.jetbrains.kotlin.codegen.OwnerKind
 import org.jetbrains.kotlin.codegen.StackValue
-import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrMemberAccessExpression
 import org.jetbrains.kotlin.ir.expressions.IrStatementOrigin
@@ -68,10 +67,10 @@ class IrCompareTo : IntrinsicMethod() {
         val rightType = argTypes[1]
         val parameterType = comparisonOperandType(leftType, rightType)
 
-        val newSignature = context.state.typeMapper.mapSignatureSkipGeneric(compareCall.descriptor as FunctionDescriptor, OwnerKind.IMPLEMENTATION)
+        val newSignature = context.state.typeMapper.mapSignatureSkipGeneric(compareCall.descriptor, OwnerKind.IMPLEMENTATION)
         return object : IrIntrinsicFunction(compareCall, newSignature, context, listOf(parameterType, parameterType)) {
             override fun invoke(v: InstructionAdapter, codegen: ExpressionCodegen, data: BlockInfo): StackValue {
-                val isPrimitiveIntrinsic = codegen.intrinsics.intrinsics.getIntrinsic(compareCall.descriptor as FunctionDescriptor) != null
+                val isPrimitiveIntrinsic = codegen.intrinsics.intrinsics.getIntrinsic(compareCall.descriptor) != null
                 val operationType: Type
                 val leftValue: StackValue
                 val rightValue: StackValue

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/SyntheticAccessorLowering.kt

@@ -81,7 +81,7 @@ class ContextAnnotator(val state: GenerationState) : ClassLowerWithContext() {
 
     override fun lowerBefore(irClass: IrClass, data: IrClassContext) {
         val descriptor = irClass.descriptor
-        val newContext: CodegenContext<*> = if (descriptor is FileClassDescriptor || descriptor !is ClassDescriptor) {
+        val newContext: CodegenContext<*> = if (descriptor is FileClassDescriptor) {
             StubCodegenContext(descriptor, data.parent?.codegenContext, data)
         }
         else {

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFieldImpl.kt

@@ -59,6 +59,6 @@ class IrFieldImpl(
     }
 
     override fun <D> transformChildren(transformer: IrElementTransformer<D>, data: D) {
-        initializer = initializer?.transform(transformer, data) as? IrExpressionBody
+        initializer = initializer?.transform(transformer, data)
     }
 }

compiler/light-classes/src/org/jetbrains/kotlin/asJava/elements/KtLightMethodImpl.kt

@@ -114,7 +114,7 @@ class KtLightMethodImpl private constructor(
         if (calculatingReturnType.get() == true) {
             return KotlinJavaPsiFacade.getInstance(project).emptyModifierList
         }
-        return super.getModifierList()!!
+        return super.getModifierList()
     }
 
     override fun getParameterList() = paramsList
@@ -235,7 +235,7 @@ fun KtLightMethod.isTraitFakeOverride(): Boolean {
     }
 
     val parentOfMethodOrigin = PsiTreeUtil.getParentOfType(methodOrigin, KtClassOrObject::class.java)
-    val thisClassDeclaration = (this.containingClass as KtLightClass).kotlinOrigin
+    val thisClassDeclaration = this.containingClass.kotlinOrigin
 
     // Method was generated from declaration in some other trait
     return (parentOfMethodOrigin != null && thisClassDeclaration !== parentOfMethodOrigin && KtPsiUtil.isTrait(parentOfMethodOrigin))

compiler/tests/org/jetbrains/kotlin/daemon/CompilerDaemonTest.kt

@@ -670,7 +670,7 @@ class CompilerDaemonTest : KotlinIntegrationTestBase() {
 
     fun testDaemonReplLocalEvalNoParams() {
         withDaemon { daemon ->
-            val repl = KotlinRemoteReplCompilerClient(daemon!!, null, CompileService.TargetPlatform.JVM,
+            val repl = KotlinRemoteReplCompilerClient(daemon, null, CompileService.TargetPlatform.JVM,
                                                       emptyArray(),
                                                       TestMessageCollector(),
                                                       classpathFromClassloader(),
@@ -685,7 +685,7 @@ class CompilerDaemonTest : KotlinIntegrationTestBase() {
 
     fun testDaemonReplLocalEvalStandardTemplate() {
         withDaemon { daemon ->
-            val repl = KotlinRemoteReplCompilerClient(daemon!!, null, CompileService.TargetPlatform.JVM, emptyArray(),
+            val repl = KotlinRemoteReplCompilerClient(daemon, null, CompileService.TargetPlatform.JVM, emptyArray(),
                                                       TestMessageCollector(),
                                                       classpathFromClassloader(),
                                                       "kotlin.script.templates.standard.ScriptTemplateWithArgs")

idea/ide-common/src/org/jetbrains/kotlin/idea/util/CallType.kt

@@ -278,8 +278,6 @@ fun CallTypeAndReceiver<*, *>.receiverTypesWithIndex(
         is CallTypeAndReceiver.ANNOTATION,
         is CallTypeAndReceiver.UNKNOWN ->
             return null
-
-        else -> throw RuntimeException() //TODO: see KT-9394
     }
 
     val resolutionScope = contextElement.getResolutionScope(bindingContext, resolutionFacade)

idea/ide-common/src/org/jetbrains/kotlin/util/descriptorUtils.kt

@@ -73,7 +73,7 @@ fun ClassDescriptor.findCallableMemberBySignature(
                 if (it.containingDeclaration != this) return@firstOrNull false
                 val overridability = OverridingUtil.DEFAULT.isOverridableBy(it as CallableDescriptor, signature, null).result
                 overridability == OVERRIDABLE || (allowOverridabilityConflicts && overridability == CONFLICT)
-            } as? CallableMemberDescriptor
+            }
 }
 
 fun TypeConstructor.supertypesWithAny(): Collection<KotlinType> {

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/resolve/JavaResolveExtension.kt

@@ -128,7 +128,7 @@ private fun JavaDescriptorResolver.resolveConstructor(constructor: JavaConstruct
 }
 
 private fun JavaDescriptorResolver.resolveField(field: JavaField): PropertyDescriptor? {
-    return getContainingScope(field)?.getContributedVariables(field.name, NoLookupLocation.FROM_IDE)?.findByJavaElement(field) as? PropertyDescriptor
+    return getContainingScope(field)?.getContributedVariables(field.name, NoLookupLocation.FROM_IDE)?.findByJavaElement(field)
 }
 
 private fun JavaDescriptorResolver.getContainingScope(member: JavaMember): MemberScope? {

idea/idea-analysis/src/org/jetbrains/kotlin/idea/compiler/configuration/BaseKotlinCompilerSettings.kt

@@ -64,7 +64,7 @@ abstract class BaseKotlinCompilerSettings<T : Freezable> protected constructor()
     override fun getState() = XmlSerializer.serialize(_settings, SKIP_DEFAULT_VALUES)
 
     override fun loadState(state: Element) {
-        _settings = XmlSerializer.deserialize(state, _settings.javaClass) ?: createSettings()
+        _settings = XmlSerializer.deserialize(state, _settings.javaClass)
     }
 
     public override fun clone(): Any = super.clone()

idea/idea-analysis/src/org/jetbrains/kotlin/idea/search/usagesSearch/ExpressionsOfTypeProcessor.kt

@@ -139,7 +139,7 @@ class ExpressionsOfTypeProcessor(
         if (runReadAction { searchScope is GlobalSearchScope && !FileTypeIndex.containsFileOfType(KotlinFileType.INSTANCE, searchScope) }) return
 
         // for class from library always use plain search because we cannot search usages in compiled code (we could though)
-        if (classToSearch == null || !runReadAction { classToSearch.isValid && ProjectRootsUtil.isInProjectSource(classToSearch) }) {
+        if (!runReadAction { classToSearch.isValid && ProjectRootsUtil.isInProjectSource(classToSearch) }) {
             possibleMatchesInScopeHandler(searchScope)
             return
         }

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KeywordCompletion.kt

@@ -254,14 +254,14 @@ object KeywordCompletion {
                 is KtDeclarationWithInitializer -> {
                     val initializer = parent.initializer
                     if (prevParent == initializer) {
-                        return buildFilterWithContext("val v = ", initializer!!, position)
+                        return buildFilterWithContext("val v = ", initializer, position)
                     }
                 }
 
                 is KtParameter -> {
                     val default = parent.defaultValue
                     if (prevParent == default) {
-                        return buildFilterWithContext("val v = ", default!!, position)
+                        return buildFilterWithContext("val v = ", default, position)
                     }
                 }
 

idea/idea-core/src/org/jetbrains/kotlin/idea/core/ExpectedInfos.kt

@@ -568,7 +568,6 @@ class ExpectedInfos(
             }
 
             is PropertyGetterDescriptor -> {
-                if (descriptor !is PropertyGetterDescriptor) return null
                 val property = descriptor.correspondingProperty
                 ExpectedInfo.createForReturnValue(returnTypeToUse(property, hasExplicitReturnType), property)
             }

idea/idea-gradle/src/org/jetbrains/kotlin/idea/inspections/gradle/KotlinGradleInspectionVisitor.kt

@@ -40,7 +40,7 @@ val KOTLIN_PLUGIN_CLASSPATH_MARKER = "${KotlinWithGradleConfigurator.GROUP_ID}:$
 
 abstract class KotlinGradleInspectionVisitor : BaseInspectionVisitor() {
     override fun visitFile(file: GroovyFileBase) {
-        if (file == null || !FileUtilRt.extensionEquals(file.name, GradleConstants.EXTENSION)) return
+        if (!FileUtilRt.extensionEquals(file.name, GradleConstants.EXTENSION)) return
 
         val fileIndex = ProjectRootManager.getInstance(file.project).fileIndex
 

idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/KotlinStdJSProjectDescriptor.kt

@@ -30,7 +30,7 @@ object KotlinStdJSProjectDescriptor : KotlinLightProjectDescriptor() {
     override fun getSdk(): Sdk? = null
 
     override fun configureModule(module: Module, model: ModifiableRootModel) {
-        val configuration = JSLibraryStdDescription(module.project).createNewLibraryForTests() ?: error("Configuration should exist")
+        val configuration = JSLibraryStdDescription(module.project).createNewLibraryForTests()
 
         val editor = NewLibraryEditor(configuration.libraryType, configuration.properties)
         configuration.addRoots(editor)

idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/testUtils.kt

@@ -69,7 +69,6 @@ fun Module.configureAs(kind: ModuleKind) {
             this.configureAs(KotlinStdJSProjectDescriptor)
         }
 
-        else -> throw IllegalArgumentException("Unknown kind=$kind")
     }
 }
 

idea/src/org/jetbrains/kotlin/idea/intentions/ConvertFunctionTypeReceiverToParameterIntention.kt

@@ -62,7 +62,7 @@ class ConvertFunctionTypeReceiverToParameterIntention : SelfTargetingRangeIntent
 
     class FunctionDefinitionInfo(element: KtFunction) : AbstractProcessableUsageInfo<KtFunction, ConversionData>(element) {
         override fun process(data: ConversionData, elementsToShorten: MutableList<KtElement>) {
-            val function = element as? KtFunction ?: return
+            val function = element ?: return
             val functionParameter = function.valueParameters.getOrNull(data.functionParameterIndex) ?: return
             val functionType = functionParameter.typeReference?.typeElement as? KtFunctionType ?: return
             val functionTypeParameterList = functionType.parameterList ?: return

idea/src/org/jetbrains/kotlin/idea/intentions/DeprecatedCallableAddReplaceWithIntention.kt

@@ -196,7 +196,7 @@ class DeprecatedCallableAddReplaceWithIntention : SelfTargetingRangeIntention<Kt
         val body = bodyExpression ?: return null
         if (!hasBlockBody()) return body
         val block = body as? KtBlockExpression ?: return null
-        val statement = block.statements.singleOrNull() as? KtExpression ?: return null
+        val statement = block.statements.singleOrNull() ?: return null
         val returnsUnit = (analyze()[BindingContext.DECLARATION_TO_DESCRIPTOR, this] as? FunctionDescriptor)?.returnType?.isUnit() ?: return null
         return when (statement) {
             is KtReturnExpression -> statement.returnedExpression

idea/src/org/jetbrains/kotlin/idea/quickfix/ChangeSuspendInHierarchyFix.kt

@@ -150,7 +150,7 @@ class ChangeSuspendInHierarchyFix(
 
             return DFS.dfs(
                     listOf(this),
-                    { (it as? FunctionDescriptor)?.getOverridables() ?: emptyList() },
+                    { it?.getOverridables() ?: emptyList() },
                     object : DFS.CollectingNodeHandler<FunctionDescriptor, FunctionDescriptor, ArrayList<FunctionDescriptor>>(ArrayList()) {
                         override fun afterChildren(current: FunctionDescriptor) {
                             if (current.getOverridables().isEmpty()) {
@@ -173,7 +173,7 @@ class ChangeSuspendInHierarchyFix(
                         containingClassDescriptor.defaultType,
                         currentClassDescriptor.defaultType
                 ) ?: return@filter false
-                val signatureInCurrentClass = it.substitute(substitutor) as? FunctionDescriptor ?: return@filter false
+                val signatureInCurrentClass = it.substitute(substitutor) ?: return@filter false
                 OverridingUtil.DEFAULT.isOverridableBy(signatureInCurrentClass, currentDescriptor, null).result ==
                         OverridingUtil.OverrideCompatibilityInfo.Result.CONFLICT
             }

idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/CallableBuilder.kt

@@ -586,7 +586,6 @@ class CallableBuilder(val config: CallableBuilderConfiguration) {
             if (returnTypeRefs.isNotEmpty()) {
                 val returnType = typeCandidates[callableInfo.returnTypeInfo]!!.getTypeByRenderedType(
                         returnTypeRefs.map { it.text }
-                        ?: throw AssertionError("Expression for return type shouldn't be empty: declaration = ${declaration.text}")
                 )
                 if (returnType != null) {
                     // user selected a given type
@@ -603,7 +602,6 @@ class CallableBuilder(val config: CallableBuilderConfiguration) {
                 if (parameterTypeRef != null) {
                     val parameterType = parameterTypeExpressions[i].typeCandidates.getTypeByRenderedType(
                             listOf(parameterTypeRef.text)
-                            ?: throw AssertionError("Expression for parameter type shouldn't be empty: declaration = ${declaration.text}")
                     )
                     if (parameterType != null) {
                         replaceWithLongerName(listOf(parameterTypeRef), parameterType)

idea/src/org/jetbrains/kotlin/idea/quickfix/createFromUsage/callableBuilder/CallableInfo.kt

@@ -102,7 +102,6 @@ abstract class TypeInfo(val variance: Variance) {
                 val classDeclaration = receiverClassDescriptor?.let { DescriptorToSourceUtils.getSourceFromDescriptor(it) }
                 if (!config.isExtension && classDeclaration != null) classDeclaration else config.currentFile
             }
-            else -> throw IllegalArgumentException("Unexpected placement: $placement")
         }
         return when (containingElement) {
             is KtClassOrObject -> (containingElement.resolveToDescriptor() as? ClassDescriptorWithResolutionScopes)?.scopeForMemberDeclarationResolution

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/usages/KotlinFunctionCallUsage.kt

@@ -334,7 +334,7 @@ class KotlinFunctionCallUsage(
             if (receiverValue is ExpressionReceiver && !receiverValue.expression.isValid) {
                 receiverValue = receiverValue.wrapInvalidated(element)
             }
-            ArgumentInfo(param, index, resolvedArgument, receiverValue as? ReceiverValue)
+            ArgumentInfo(param, index, resolvedArgument, receiverValue)
         }
 
         val lastParameterIndex = newParameters.lastIndex

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/ExtractionData.kt

@@ -182,7 +182,7 @@ data class ExtractionData(
     fun getPossibleTypes(expression: KtExpression, resolvedCall: ResolvedCall<*>?, context: BindingContext): Set<KotlinType> {
         val dataFlowInfo = context.getDataFlowInfoAfter(expression)
 
-        (resolvedCall?.getImplicitReceiverValue() as? ImplicitReceiver)?.let {
+        resolvedCall?.getImplicitReceiverValue()?.let {
             return dataFlowInfo.getCollectedTypes(DataFlowValueFactory.createDataFlowValueForStableReceiver(it))
         }
 

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceParameter/KotlinIntroduceParameterHandler.kt

@@ -282,7 +282,7 @@ open class KotlinIntroduceParameterHandler(
                             is KtExpression -> matchedElement
                             is KtStringTemplateEntryWithExpression -> matchedElement.expression
                             else -> null
-                        } as? KtExpression
+                        }
                         matchedExpr?.toRange()
                     }
         }

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceVariable/KotlinIntroduceVariableHandler.kt

@@ -211,7 +211,7 @@ object KotlinIntroduceVariableHandler : RefactoringActionHandler {
                     actualExpression = reference!!
                     diff = actualExpression.textRange.startOffset - emptyBody.textRange.startOffset
                     actualExpressionText = actualExpression.text
-                    emptyBody = anchor!!.replace(emptyBody) as KtBlockExpression
+                    emptyBody = anchor.replace(emptyBody) as KtBlockExpression
                     elem = findElementByOffsetAndText(diff, actualExpressionText, emptyBody)
                     if (elem != null) {
                         reference = elem as KtExpression
@@ -335,7 +335,7 @@ object KotlinIntroduceVariableHandler : RefactoringActionHandler {
                         is KtExpression -> candidate
                         is KtStringTemplateEntryWithExpression -> candidate.expression
                         else -> throw AssertionError("Unexpected candidate element: " + candidate.text)
-                    } as? KtExpression
+                    }
                 }
     }
 

idea/src/org/jetbrains/kotlin/idea/refactoring/kotlinRefactoringUtil.kt

@@ -953,7 +953,7 @@ fun checkSuperMethodsWithPopup(
             .setResizable(false)
             .setRequestFocus(true)
             .setItemChoosenCallback {
-                val value = list.selectedValue as? String ?: return@setItemChoosenCallback
+                val value = list.selectedValue ?: return@setItemChoosenCallback
                 val chosenElements = if (value == renameBase) deepestSuperMethods + declaration else listOf(declaration)
                 action(chosenElements)
             }

idea/src/org/jetbrains/kotlin/idea/refactoring/memberInfo/KotlinMemberInfoStorage.kt

@@ -100,8 +100,6 @@ fun extractClassMembers(
                 .mapTo(result) { KotlinMemberInfo(it as KtNamedDeclaration, isCompanionMember = isCompanion) }
     }
 
-    if (aClass !is KtClassOrObject) return emptyList()
-
     val result = ArrayList<KotlinMemberInfo>()
 
     if (collectSuperTypeEntries) {

idea/src/org/jetbrains/kotlin/idea/refactoring/move/moveFilesUtil.kt

@@ -50,7 +50,7 @@ fun invokeMoveFilesOrDirectoriesRefactoring(
 
     project.executeCommand(MoveHandler.REFACTORING_NAME) {
         val selectedDir = (if (moveDialog != null) moveDialog.targetDirectory else initialTargetDirectory) ?: return@executeCommand
-        val updatePackageDirective = (moveDialog as? KotlinAwareMoveFilesOrDirectoriesDialog)?.updatePackageDirective
+        val updatePackageDirective = moveDialog?.updatePackageDirective
 
         try {
             val choice = if (elements.size > 1 || elements[0] is PsiDirectory) intArrayOf(-1) else null

idea/src/org/jetbrains/kotlin/idea/refactoring/pullUp/markingUtils.kt

@@ -76,7 +76,6 @@ fun markElements(
                                    ?: resolvedCall.extensionReceiver
                                    ?: resolvedCall.dispatchReceiver
                                    ?: return
-                    if (receiver !is ReceiverValue) return
 
                     val implicitThis = receiver.type.constructor.declarationDescriptor as? ClassDescriptor ?: return
                     if (implicitThis.isCompanionObject

idea/src/org/jetbrains/kotlin/idea/refactoring/rename/RenameImportAliasByReferenceHandler.kt

@@ -24,7 +24,7 @@ import org.jetbrains.kotlin.psi.KtSimpleNameExpression
 
 class RenameImportAliasByReferenceHandler : AbstractReferenceSubstitutionRenameHandler(VariableInplaceRenameHandler()) {
     override fun getElementToRename(dataContext: DataContext): PsiElement? {
-        val refExpr = getReferenceExpression(dataContext) as? KtSimpleNameExpression ?: return null
+        val refExpr = getReferenceExpression(dataContext) ?: return null
         return refExpr.mainReference.getImportAlias()
     }
 }

idea/src/org/jetbrains/kotlin/idea/search/ideaExtensions/KotlinOverridingMethodsWithGenericsSearcher.kt

@@ -47,7 +47,7 @@ class KotlinOverridingMethodsWithGenericsSearcher : QueryExecutor<PsiMethod, Ove
         // we do additional search for such methods.
         if (!callDescriptor.valueParameters.any { it.type.constructor.declarationDescriptor is TypeParameterDescriptor }) return true
 
-        val parentClass = runReadAction { method.containingClass }!!
+        val parentClass = runReadAction { method.containingClass }
 
         return ClassInheritorsSearch.search(parentClass, p.scope, true).forEach(Processor { inheritor: PsiClass ->
             val found = runReadAction {

idea/tests/org/jetbrains/kotlin/idea/configuration/AbstractConfigureKotlinTest.kt

@@ -153,13 +153,10 @@ abstract class AbstractConfigureKotlinTest : PlatformTestCase() {
             collector.showNotification()
         }
 
-        private fun getPathToJar(runtimeState: FileState, jarFromDist: String, jarFromTemp: String): String {
+        private fun getPathToJar(runtimeState: FileState, jarFromDist: String, jarFromTemp: String) = when (runtimeState) {
-            when (runtimeState) {
+            KotlinWithLibraryConfigurator.FileState.EXISTS -> jarFromDist
-                KotlinWithLibraryConfigurator.FileState.EXISTS -> return jarFromDist
+            KotlinWithLibraryConfigurator.FileState.COPY -> jarFromTemp
-                KotlinWithLibraryConfigurator.FileState.COPY -> return jarFromTemp
+            KotlinWithLibraryConfigurator.FileState.DO_NOT_COPY -> jarFromDist
-                KotlinWithLibraryConfigurator.FileState.DO_NOT_COPY -> return jarFromDist
-            }
-            return jarFromDist
         }
 
         protected fun configure(module: Module, jarState: FileState, configurator: KotlinProjectConfigurator) {

idea/tests/org/jetbrains/kotlin/idea/refactoring/InplaceRenameTest.kt

@@ -102,7 +102,7 @@ class InplaceRenameTest : LightPlatformCodeInsightTestCase() {
         val element = file.findElementForRename<KtNameReferenceExpression>(editor.caretModel.offset)!!
         assertNotNull(element)
 
-        val dataContext = SimpleDataContext.getSimpleContext(CommonDataKeys.PSI_ELEMENT.name, element!!,
+        val dataContext = SimpleDataContext.getSimpleContext(CommonDataKeys.PSI_ELEMENT.name, element,
                                                              getCurrentEditorDataContext())
         val handler = RenameKotlinImplicitLambdaParameter()
 

idea/tests/org/jetbrains/kotlin/idea/refactoring/changeSignature/KotlinChangeSignatureTest.kt

@@ -157,7 +157,7 @@ class KotlinChangeSignatureTest : KotlinLightCodeInsightFixtureTestCase() {
             val message = when {
                 e is BaseRefactoringProcessor.ConflictsInTestsException -> StringUtil.join(e.messages.sorted(), "\n")
                 e is CommonRefactoringUtil.RefactoringErrorHintException -> e.message
-                e is RuntimeException && e.message!!.startsWith("Refactoring cannot be performed") -> e.message
+                e.message!!.startsWith("Refactoring cannot be performed") -> e.message
                 else -> throw e
             }
             val conflictsFile = File(testDataPath + getTestName(false) + "Messages.txt")

j2k/src/org/jetbrains/kotlin/j2k/ForConverter.kt

@@ -235,7 +235,7 @@ class ForConverter(
         // check if it's iteration through list indices
         if (collectionSize is PsiMethodCallExpression && collectionSize.argumentList.expressions.isEmpty()) {
             val methodExpr = collectionSize.methodExpression
-            if (methodExpr is PsiReferenceExpression && methodExpr.referenceName == "size") {
+            if (methodExpr.referenceName == "size") {
                 val qualifier = methodExpr.qualifierExpression
                 if (qualifier is PsiReferenceExpression /* we don't convert to .indices if qualifier is method call or something because of possible side effects */) {
                     val collectionType = PsiElementFactory.SERVICE.getInstance(project).createTypeByFQClassName(CommonClassNames.JAVA_UTIL_COLLECTION)

j2k/src/org/jetbrains/kotlin/j2k/ast/TypeParameters.kt

@@ -72,7 +72,7 @@ private fun Converter.convertTypeParameter(typeParameter: PsiTypeParameter): Typ
 
 fun Converter.convertTypeParameterList(typeParameterList: PsiTypeParameterList?): TypeParameterList {
     return if (typeParameterList != null)
-        TypeParameterList(typeParameterList.typeParameters!!.toList().map { convertTypeParameter(it) }).assignPrototype(typeParameterList)
+        TypeParameterList(typeParameterList.typeParameters.toList().map { convertTypeParameter(it) }).assignPrototype(typeParameterList)
     else
         TypeParameterList.Empty
 }

jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/build/KotlinJpsBuildTest.kt

@@ -1094,8 +1094,6 @@ open class KotlinJpsBuildTest : AbstractKotlinJpsBuildTestCase() {
                     touch(file)
                 Operation.DELETE ->
                     assertTrue("Can not delete file \"" + file.absolutePath + "\"", file.delete())
-                else ->
-                    fail("Unknown operation")
             }
         }
     }

jps-plugin/src/org/jetbrains/kotlin/jps/model/Kotlin2JsCompilerArgumentsSerializer.kt

@@ -28,7 +28,7 @@ import org.jetbrains.kotlin.jps.JpsKotlinCompilerSettings
 internal class Kotlin2JsCompilerArgumentsSerializer : JpsProjectExtensionSerializer(KOTLIN_COMPILER_SETTINGS_FILE,
                                                                                     KOTLIN_TO_JS_COMPILER_ARGUMENTS_SECTION) {
     override fun loadExtension(project: JpsProject, componentTag: Element) {
-        val settings = XmlSerializer.deserialize(componentTag, K2JSCompilerArguments::class.java) ?: K2JSCompilerArguments()
+        val settings = XmlSerializer.deserialize(componentTag, K2JSCompilerArguments::class.java)
         JpsKotlinCompilerSettings.setK2JsCompilerArguments(project, settings)
     }
 

jps-plugin/src/org/jetbrains/kotlin/jps/model/Kotlin2JvmCompilerArgumentsSerializer.kt

@@ -30,7 +30,7 @@ internal class Kotlin2JvmCompilerArgumentsSerializer : JpsProjectExtensionSerial
                                                                                      KOTLIN_TO_JVM_COMPILER_ARGUMENTS_SECTION) {
 
     override fun loadExtension(project: JpsProject, componentTag: Element) {
-        val settings = XmlSerializer.deserialize(componentTag, K2JVMCompilerArguments::class.java) ?: K2JVMCompilerArguments()
+        val settings = XmlSerializer.deserialize(componentTag, K2JVMCompilerArguments::class.java)
         JpsKotlinCompilerSettings.setK2JvmCompilerArguments(project, settings)
     }
 

jps-plugin/src/org/jetbrains/kotlin/jps/model/KotlinCommonCompilerArgumentsSerializer.kt

@@ -31,7 +31,6 @@ internal class KotlinCommonCompilerArgumentsSerializer : JpsProjectExtensionSeri
 
     override fun loadExtension(project: JpsProject, componentTag: Element) {
         val settings = XmlSerializer.deserialize(componentTag, CommonCompilerArguments.DummyImpl::class.java)
-                       ?: CommonCompilerArguments.DummyImpl()
         if (VersionComparatorUtil.compare(settings.languageVersion, settings.apiVersion) < 0) {
             settings.apiVersion = settings.languageVersion
         }

jps-plugin/src/org/jetbrains/kotlin/jps/model/KotlinCompilerSettingsSerializer.kt

@@ -30,7 +30,7 @@ internal class KotlinCompilerSettingsSerializer : JpsProjectExtensionSerializer(
                                                                                 KOTLIN_COMPILER_SETTINGS_SECTION) {
 
     override fun loadExtension(project: JpsProject, componentTag: Element) {
-        val settings = XmlSerializer.deserialize(componentTag, CompilerSettings::class.java) ?: CompilerSettings()
+        val settings = XmlSerializer.deserialize(componentTag, CompilerSettings::class.java)
         JpsKotlinCompilerSettings.setCompilerSettings(project, settings)
     }
 

js/js.tests/test/org/jetbrains/kotlin/js/test/BasicBoxTest.kt

@@ -397,9 +397,7 @@ abstract class BasicBoxTest(
                 FileUtil.writeToFile(File(incrementalDir, "$i.$METADATA_EXTENSION"), packagePart.proto)
             }
 
-            incrementalService.headerMetadata?.let {
+            FileUtil.writeToFile(File(incrementalDir, HEADER_FILE), incrementalService.headerMetadata)
-                FileUtil.writeToFile(File(incrementalDir, HEADER_FILE), it)
-            }
         }
 
         processJsProgram(translationResult.program, units.filterIsInstance<TranslationUnit.SourceFile>().map { it.file })

plugins/android-extensions/android-extensions-idea/src/org/jetbrains/kotlin/android/synthetic/idea/AndroidPsiTreeChangePreprocessor.kt

@@ -21,7 +21,6 @@ import com.intellij.openapi.roots.ProjectRootManager
 import com.intellij.openapi.util.SimpleModificationTracker
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.openapi.vfs.VirtualFileManager
-import com.intellij.psi.PsiDirectory
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiFile
 import com.intellij.psi.impl.PsiTreeChangeEventImpl
@@ -83,7 +82,7 @@ class AndroidPsiTreeChangePreprocessor : PsiTreeChangePreprocessor, SimpleModifi
 
             val projectFileIndex = ProjectRootManager.getInstance(xmlFile.project).fileIndex
             val module = projectFileIndex.getModuleForFile(xmlFile.virtualFile)
-                         ?: (element.parent as? PsiDirectory)?.let { projectFileIndex.getModuleForFile(it.virtualFile) }
+                         ?: element.parent?.let { projectFileIndex.getModuleForFile(it.virtualFile) }
 
             if (module != null && !module.isDisposed) {
                 val resourceManager = AndroidLayoutXmlFileManager.getInstance(module) ?: return false

plugins/uast-kotlin/src/org/jetbrains/uast/kotlin/KotlinUastLanguagePlugin.kt

@@ -59,13 +59,11 @@ class KotlinUastLanguagePlugin : UastLanguagePlugin {
     }
 
     override fun convertElement(element: PsiElement, parent: UElement?, requiredType: Class<out UElement>?): UElement? {
-        if (element !is PsiElement) return null
         return convertDeclaration(element, parent.toCallback(), requiredType)
                ?: KotlinConverter.convertPsiElement(element, parent.toCallback(), requiredType)
     }
     
     override fun convertElementWithParent(element: PsiElement, requiredType: Class<out UElement>?): UElement? {
-        if (element !is PsiElement) return null
         if (element is PsiFile) return convertDeclaration(element, null, requiredType)
         if (element is KtLightClassForFacade) return convertDeclaration(element, null, requiredType)