Cleanup: apply "cascade if..." inspection (+ some others)

compiler/backend/src/org/jetbrains/kotlin/codegen/codegenUtil.kt

@@ -292,14 +292,10 @@ fun calcTypeForIEEE754ArithmeticIfNeeded(expression: KtExpression?, bindingConte
     val dataFlow = DataFlowValueFactory.createDataFlowValue(expression!!, ktType, bindingContext, descriptor)
     val stableTypes = bindingContext.getDataFlowInfoBefore(expression).getStableTypes(dataFlow)
     return stableTypes.firstNotNullResult {
-        if (KotlinBuiltIns.isDoubleOrNullableDouble(it)) {
-            TypeAndNullability(Type.DOUBLE_TYPE, TypeUtils.isNullableType(it))
-        }
-        else if (KotlinBuiltIns.isFloatOrNullableFloat(it)) {
-            TypeAndNullability(Type.FLOAT_TYPE, TypeUtils.isNullableType(it))
-        }
-        else {
-            null
+        when {
+            KotlinBuiltIns.isDoubleOrNullableDouble(it) -> TypeAndNullability(Type.DOUBLE_TYPE, TypeUtils.isNullableType(it))
+            KotlinBuiltIns.isFloatOrNullableFloat(it) -> TypeAndNullability(Type.FLOAT_TYPE, TypeUtils.isNullableType(it))
+            else -> null
         }
     }
 }

compiler/backend/src/org/jetbrains/kotlin/codegen/forLoop/ForLoopGenerators.kt

@@ -83,18 +83,16 @@ private fun ExpressionCodegen.createOptimizedForLoopGeneratorOrNull(
 private fun getLoopRangeResolvedCall(forExpression: KtForExpression, bindingContext: BindingContext): ResolvedCall<out CallableDescriptor>? {
     val loopRange = KtPsiUtil.deparenthesize(forExpression.loopRange)
 
-    if (loopRange is KtQualifiedExpression) {
-        val qualifiedExpression = loopRange as KtQualifiedExpression?
-        val selector = qualifiedExpression!!.selectorExpression
-        if (selector is KtCallExpression || selector is KtSimpleNameExpression) {
-            return selector.getResolvedCall(bindingContext)
+    when (loopRange) {
+        is KtQualifiedExpression -> {
+            val qualifiedExpression = loopRange as KtQualifiedExpression?
+            val selector = qualifiedExpression!!.selectorExpression
+            if (selector is KtCallExpression || selector is KtSimpleNameExpression) {
+                return selector.getResolvedCall(bindingContext)
+            }
         }
-    }
-    else if (loopRange is KtSimpleNameExpression || loopRange is KtCallExpression) {
-        return loopRange.getResolvedCall(bindingContext)
-    }
-    else if (loopRange is KtBinaryExpression) {
-        return loopRange.operationReference.getResolvedCall(bindingContext)
+        is KtSimpleNameExpression, is KtCallExpression -> return loopRange.getResolvedCall(bindingContext)
+        is KtBinaryExpression -> return loopRange.operationReference.getResolvedCall(bindingContext)
     }
 
     return null

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/InlineCodegen.kt

@@ -610,14 +610,10 @@ class PsiInlineCodegen(
 
     override fun putClosureParametersOnStack(next: LambdaInfo, functionReferenceReceiver: StackValue?) {
         activeLambda = next
-        if (next is ExpressionLambda) {
-            codegen.pushClosureOnStack(next.classDescriptor, true, this, functionReferenceReceiver)
-        }
-        else if (next is DefaultLambda) {
-            rememberCapturedForDefaultLambda(next)
-        }
-        else {
-            throw RuntimeException("Unknown lambda: $next")
+        when (next) {
+            is ExpressionLambda -> codegen.pushClosureOnStack(next.classDescriptor, true, this, functionReferenceReceiver)
+            is DefaultLambda -> rememberCapturedForDefaultLambda(next)
+            else -> throw RuntimeException("Unknown lambda: $next")
         }
         activeLambda = null
     }

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/SourceCompilerForInline.kt

@@ -408,23 +408,27 @@ class PsiSourceCompilerForInline(private val codegen: ExpressionCodegen, overrid
                     sourceFile
             )
 
-            if (descriptor is ScriptDescriptor) {
-                val earlierScripts = state.replSpecific.earlierScriptsForReplInterpreter
-                return parent.intoScript(
-                        descriptor,
-                        earlierScripts ?: emptyList(),
-                        descriptor as ClassDescriptor, state.typeMapper
-                )
-            }
-            else if (descriptor is ClassDescriptor) {
-                val kind = if (DescriptorUtils.isInterface(descriptor)) OwnerKind.DEFAULT_IMPLS else OwnerKind.IMPLEMENTATION
-                return parent.intoClass(descriptor, kind, state)
-            }
-            else if (descriptor is FunctionDescriptor) {
-                return parent.intoFunction(descriptor)
+            return when (descriptor) {
+                is ScriptDescriptor -> {
+                    val earlierScripts = state.replSpecific.earlierScriptsForReplInterpreter
+                    parent.intoScript(
+                            descriptor,
+                            earlierScripts ?: emptyList(),
+                            descriptor as ClassDescriptor, state.typeMapper
+                    )
+                }
+                is ClassDescriptor -> {
+                    val kind = if (DescriptorUtils.isInterface(descriptor)) OwnerKind.DEFAULT_IMPLS else OwnerKind.IMPLEMENTATION
+                    parent.intoClass(descriptor, kind, state)
+                }
+                is FunctionDescriptor -> {
+                    parent.intoFunction(descriptor)
+                }
+                else -> {
+                    throw IllegalStateException("Couldn't build context for " + descriptor)
+                }
             }
 
-            throw IllegalStateException("Couldn't build context for " + descriptor)
         }
     }
 }

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/inlineCodegenUtils.kt

@@ -171,33 +171,35 @@ private fun getInlineName(
         typeMapper: KotlinTypeMapper,
         fileClassesProvider: JvmFileClassesProvider
 ): String {
-    if (currentDescriptor is PackageFragmentDescriptor) {
-        val file = DescriptorToSourceUtils.getContainingFile(codegenContext.contextDescriptor)
+    when (currentDescriptor) {
+        is PackageFragmentDescriptor -> {
+            val file = DescriptorToSourceUtils.getContainingFile(codegenContext.contextDescriptor)
 
-        val implementationOwnerType: Type? =
-                if (file == null) {
-                    CodegenContextUtil.getImplementationOwnerClassType(codegenContext)
-                }
-                else fileClassesProvider.getFileClassType(file)
+            val implementationOwnerType: Type? =
+                    if (file == null) {
+                        CodegenContextUtil.getImplementationOwnerClassType(codegenContext)
+                    }
+                    else fileClassesProvider.getFileClassType(file)
 
-        if (implementationOwnerType == null) {
-            val contextDescriptor = codegenContext.contextDescriptor
-            throw RuntimeException(
-                    "Couldn't find declaration for " +
-                    contextDescriptor.containingDeclaration!!.name + "." + contextDescriptor.name +
-                    "; context: " + codegenContext
-            )
+            if (implementationOwnerType == null) {
+                val contextDescriptor = codegenContext.contextDescriptor
+                throw RuntimeException(
+                        "Couldn't find declaration for " +
+                        contextDescriptor.containingDeclaration!!.name + "." + contextDescriptor.name +
+                        "; context: " + codegenContext
+                )
+            }
+
+            return implementationOwnerType.internalName
         }
-
-        return implementationOwnerType.internalName
-    }
-    else if (currentDescriptor is ClassifierDescriptor) {
-        return typeMapper.mapType(currentDescriptor).internalName
-    }
-    else if (currentDescriptor is FunctionDescriptor) {
-        val descriptor = typeMapper.bindingContext.get(CodegenBinding.CLASS_FOR_CALLABLE, currentDescriptor)
-        if (descriptor != null) {
-            return typeMapper.mapType(descriptor).internalName
+        is ClassifierDescriptor -> {
+            return typeMapper.mapType(currentDescriptor).internalName
+        }
+        is FunctionDescriptor -> {
+            val descriptor = typeMapper.bindingContext.get(CodegenBinding.CLASS_FOR_CALLABLE, currentDescriptor)
+            if (descriptor != null) {
+                return typeMapper.mapType(descriptor).internalName
+            }
         }
     }
 

compiler/backend/src/org/jetbrains/kotlin/codegen/intrinsics/JavaClassProperty.kt

@@ -43,21 +43,23 @@ object JavaClassProperty : IntrinsicPropertyGetter() {
 
     fun generateImpl(v: InstructionAdapter, receiver: StackValue): Type {
         val type = receiver.type
-        if (type == Type.VOID_TYPE) {
-            receiver.put(Type.VOID_TYPE, v)
-            StackValue.unit().put(UNIT_TYPE, v)
-            v.invokevirtual("java/lang/Object", "getClass", "()Ljava/lang/Class;", false)
-        }
-        else if (isPrimitive(type)) {
-            if (!StackValue.couldSkipReceiverOnStaticCall(receiver)) {
-                receiver.put(type, v)
-                AsmUtil.pop(v, type)
+        when {
+            type == Type.VOID_TYPE -> {
+                receiver.put(Type.VOID_TYPE, v)
+                StackValue.unit().put(UNIT_TYPE, v)
+                v.invokevirtual("java/lang/Object", "getClass", "()Ljava/lang/Class;", false)
+            }
+            isPrimitive(type) -> {
+                if (!StackValue.couldSkipReceiverOnStaticCall(receiver)) {
+                    receiver.put(type, v)
+                    AsmUtil.pop(v, type)
+                }
+                v.getstatic(boxType(type).internalName, "TYPE", "Ljava/lang/Class;")
+            }
+            else -> {
+                receiver.put(type, v)
+                v.invokevirtual("java/lang/Object", "getClass", "()Ljava/lang/Class;", false)
             }
-            v.getstatic(boxType(type).internalName, "TYPE", "Ljava/lang/Class;")
-        }
-        else {
-            receiver.put(type, v)
-            v.invokevirtual("java/lang/Object", "getClass", "()Ljava/lang/Class;", false)
         }
 
         return getType(Class::class.java)

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowInformationProvider.kt

@@ -1123,15 +1123,10 @@ class ControlFlowInformationProvider private constructor(
                 kind
             }
             else {
-                if (check(kind, existingKind, IN_TRY, TAIL_CALL)) {
-                    IN_TRY
-                }
-                else if (check(kind, existingKind, IN_TRY, NON_TAIL)) {
-                    IN_TRY
-                }
-                else {
-                    // TAIL_CALL, NON_TAIL
-                    NON_TAIL
+                when {
+                    check(kind, existingKind, IN_TRY, TAIL_CALL) -> IN_TRY
+                    check(kind, existingKind, IN_TRY, NON_TAIL) -> IN_TRY
+                    else -> NON_TAIL // TAIL_CALL, NON_TAIL
                 }
             }
         }

compiler/frontend/src/org/jetbrains/kotlin/cfg/UnreachableCode.kt

@@ -107,15 +107,17 @@ class UnreachableCodeImpl(
             currentTextRange, element ->
 
             val elementRange = element.textRange!!
-            if (currentTextRange == null) {
-                elementRange
-            }
-            else if (currentTextRange.endOffset == elementRange.startOffset) {
-                currentTextRange.union(elementRange)
-            }
-            else {
-                result.add(currentTextRange)
-                elementRange
+            when {
+                currentTextRange == null -> {
+                    elementRange
+                }
+                currentTextRange.endOffset == elementRange.startOffset -> {
+                    currentTextRange.union(elementRange)
+                }
+                else -> {
+                    result.add(currentTextRange)
+                    elementRange
+                }
             }
         }
         if (lastRange != null) {

compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/SyntheticFieldDescriptor.kt

@@ -47,4 +47,8 @@ class SyntheticFieldDescriptor private constructor(
 }
 
 val DeclarationDescriptor.referencedProperty: PropertyDescriptor?
-    get() = if (this is SyntheticFieldDescriptor) this.propertyDescriptor else if (this is PropertyDescriptor) this else null
+    get() = when (this) {
+        is SyntheticFieldDescriptor -> this.propertyDescriptor
+        is PropertyDescriptor -> this
+        else -> null
+    }

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/Renderers.kt

@@ -458,7 +458,11 @@ object Renderers {
 
     private fun renderTypeBounds(typeBounds: TypeBounds, short: Boolean): String {
         val renderBound = { bound: Bound ->
-            val arrow = if (bound.kind == LOWER_BOUND) ">: " else if (bound.kind == UPPER_BOUND) "<: " else ":= "
+            val arrow = when (bound.kind) {
+                LOWER_BOUND -> ">: "
+                UPPER_BOUND -> "<: "
+                else -> ":= "
+            }
             val renderer = if (short) DescriptorRenderer.SHORT_NAMES_IN_TYPES else DescriptorRenderer.FQ_NAMES_IN_TYPES
             val renderedBound = arrow + renderer.renderType(bound.constrainingType) +  if (!bound.isProper) "*" else ""
             if (short) renderedBound else renderedBound + '(' + bound.position + ')'

compiler/frontend/src/org/jetbrains/kotlin/resolve/AnnotationChecker.kt

@@ -202,32 +202,28 @@ class AnnotationChecker(private val additionalCheckers: Iterable<AdditionalAnnot
                     (descriptor as? ClassDescriptor)?.let { TargetList(KotlinTarget.classActualTargets(it)) } ?: TargetLists.T_CLASSIFIER
                 is KtDestructuringDeclarationEntry -> TargetLists.T_LOCAL_VARIABLE
                 is KtProperty -> {
-                    if (annotated.isLocal)
-                        TargetLists.T_LOCAL_VARIABLE
-                    else if (annotated.isMember)
-                        TargetLists.T_MEMBER_PROPERTY(descriptor.hasBackingField(trace), annotated.hasDelegate())
-                    else
-                        TargetLists.T_TOP_LEVEL_PROPERTY(descriptor.hasBackingField(trace), annotated.hasDelegate())
+                    when {
+                        annotated.isLocal -> TargetLists.T_LOCAL_VARIABLE
+                        annotated.isMember -> TargetLists.T_MEMBER_PROPERTY(descriptor.hasBackingField(trace), annotated.hasDelegate())
+                        else -> TargetLists.T_TOP_LEVEL_PROPERTY(descriptor.hasBackingField(trace), annotated.hasDelegate())
+                    }
                 }
                 is KtParameter -> {
                     val destructuringDeclaration = annotated.destructuringDeclaration
-                    if (destructuringDeclaration != null)
-                        TargetLists.T_DESTRUCTURING_DECLARATION
-                    else if (annotated.hasValOrVar())
-                        TargetLists.T_VALUE_PARAMETER_WITH_VAL
-                    else
-                        TargetLists.T_VALUE_PARAMETER_WITHOUT_VAL
+                    when {
+                        destructuringDeclaration != null -> TargetLists.T_DESTRUCTURING_DECLARATION
+                        annotated.hasValOrVar() -> TargetLists.T_VALUE_PARAMETER_WITH_VAL
+                        else -> TargetLists.T_VALUE_PARAMETER_WITHOUT_VAL
+                    }
                 }
                 is KtConstructor<*> -> TargetLists.T_CONSTRUCTOR
                 is KtFunction -> {
-                    if (ExpressionTypingUtils.isFunctionExpression(descriptor))
-                        TargetLists.T_FUNCTION_EXPRESSION
-                    else if (annotated.isLocal)
-                        TargetLists.T_LOCAL_FUNCTION
-                    else if (annotated.parent is KtClassOrObject || annotated.parent is KtClassBody)
-                        TargetLists.T_MEMBER_FUNCTION
-                    else
-                        TargetLists.T_TOP_LEVEL_FUNCTION
+                    when {
+                        ExpressionTypingUtils.isFunctionExpression(descriptor) -> TargetLists.T_FUNCTION_EXPRESSION
+                        annotated.isLocal -> TargetLists.T_LOCAL_FUNCTION
+                        annotated.parent is KtClassOrObject || annotated.parent is KtClassBody -> TargetLists.T_MEMBER_FUNCTION
+                        else -> TargetLists.T_TOP_LEVEL_FUNCTION
+                    }
                 }
                 is KtTypeAlias -> TargetLists.T_TYPEALIAS
                 is KtPropertyAccessor -> if (annotated.isGetter) TargetLists.T_PROPERTY_GETTER else TargetLists.T_PROPERTY_SETTER
@@ -266,18 +262,20 @@ class AnnotationChecker(private val additionalCheckers: Iterable<AdditionalAnnot
             }
 
             fun T_MEMBER_PROPERTY(backingField: Boolean, delegate: Boolean) =
-                    targetList(if (backingField) MEMBER_PROPERTY_WITH_BACKING_FIELD
-                               else if (delegate) MEMBER_PROPERTY_WITH_DELEGATE
-                               else MEMBER_PROPERTY_WITHOUT_FIELD_OR_DELEGATE,
-                               MEMBER_PROPERTY, PROPERTY) {
+                    targetList(when {
+                        backingField -> MEMBER_PROPERTY_WITH_BACKING_FIELD
+                        delegate -> MEMBER_PROPERTY_WITH_DELEGATE
+                        else -> MEMBER_PROPERTY_WITHOUT_FIELD_OR_DELEGATE
+                    }, MEMBER_PROPERTY, PROPERTY) {
                         propertyTargets(backingField, delegate)
                     }
 
             fun T_TOP_LEVEL_PROPERTY(backingField: Boolean, delegate: Boolean) =
-                    targetList(if (backingField) TOP_LEVEL_PROPERTY_WITH_BACKING_FIELD
-                               else if (delegate) TOP_LEVEL_PROPERTY_WITH_DELEGATE
-                               else TOP_LEVEL_PROPERTY_WITHOUT_FIELD_OR_DELEGATE,
-                               TOP_LEVEL_PROPERTY, PROPERTY) {
+                    targetList(when {
+                        backingField -> TOP_LEVEL_PROPERTY_WITH_BACKING_FIELD
+                        delegate -> TOP_LEVEL_PROPERTY_WITH_DELEGATE
+                        else -> TOP_LEVEL_PROPERTY_WITHOUT_FIELD_OR_DELEGATE
+                    }, TOP_LEVEL_PROPERTY, PROPERTY) {
                         propertyTargets(backingField, delegate)
                     }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationsChecker.kt

@@ -418,19 +418,19 @@ class DeclarationsChecker(
         FiniteBoundRestrictionChecker.check(aClass, classDescriptor, trace)
         NonExpansiveInheritanceRestrictionChecker.check(aClass, classDescriptor, trace)
 
-        if (aClass.isInterface()) {
-            checkConstructorInInterface(aClass)
-            checkMethodsOfAnyInInterface(classDescriptor)
-            if (aClass.isLocal && classDescriptor.containingDeclaration !is ClassDescriptor) {
-                trace.report(LOCAL_INTERFACE_NOT_ALLOWED.on(aClass, classDescriptor))
+        when {
+            aClass.isInterface() -> {
+                checkConstructorInInterface(aClass)
+                checkMethodsOfAnyInInterface(classDescriptor)
+                if (aClass.isLocal && classDescriptor.containingDeclaration !is ClassDescriptor) {
+                    trace.report(LOCAL_INTERFACE_NOT_ALLOWED.on(aClass, classDescriptor))
+                }
             }
-        }
-        else if (classDescriptor.kind == ClassKind.ANNOTATION_CLASS) {
-            checkAnnotationClassWithBody(aClass)
-            checkValOnAnnotationParameter(aClass)
-        }
-        else if (aClass is KtEnumEntry) {
-            checkEnumEntry(aClass, classDescriptor)
+            classDescriptor.kind == ClassKind.ANNOTATION_CLASS -> {
+                checkAnnotationClassWithBody(aClass)
+                checkValOnAnnotationParameter(aClass)
+            }
+            aClass is KtEnumEntry -> checkEnumEntry(aClass, classDescriptor)
         }
     }
 
@@ -692,17 +692,11 @@ class DeclarationsChecker(
         val delegate = property.delegate
         val isHeader = propertyDescriptor.isHeader
         if (initializer != null) {
-            if (inInterface) {
-                trace.report(PROPERTY_INITIALIZER_IN_INTERFACE.on(initializer))
-            }
-            else if (isHeader) {
-                trace.report(HEADER_PROPERTY_INITIALIZER.on(initializer))
-            }
-            else if (!backingFieldRequired) {
-                trace.report(PROPERTY_INITIALIZER_NO_BACKING_FIELD.on(initializer))
-            }
-            else if (property.receiverTypeReference != null) {
-                trace.report(EXTENSION_PROPERTY_WITH_BACKING_FIELD.on(initializer))
+            when {
+                inInterface -> trace.report(PROPERTY_INITIALIZER_IN_INTERFACE.on(initializer))
+                isHeader -> trace.report(HEADER_PROPERTY_INITIALIZER.on(initializer))
+                !backingFieldRequired -> trace.report(PROPERTY_INITIALIZER_NO_BACKING_FIELD.on(initializer))
+                property.receiverTypeReference != null -> trace.report(EXTENSION_PROPERTY_WITH_BACKING_FIELD.on(initializer))
             }
         }
         else if (delegate != null) {

compiler/frontend/src/org/jetbrains/kotlin/resolve/DelegatingBindingTrace.kt

@@ -69,12 +69,11 @@ open class DelegatingBindingTrace(
     private val bindingContext = MyBindingContext()
 
     init {
-        this.mutableDiagnostics = if (filter.ignoreDiagnostics)
-            null
-        else if (withParentDiagnostics)
-            MutableDiagnosticsWithSuppression(bindingContext, parentContext.diagnostics)
-        else
-            MutableDiagnosticsWithSuppression(bindingContext)
+        this.mutableDiagnostics = when {
+            filter.ignoreDiagnostics -> null
+            withParentDiagnostics -> MutableDiagnosticsWithSuppression(bindingContext, parentContext.diagnostics)
+            else -> MutableDiagnosticsWithSuppression(bindingContext)
+        }
     }
 
     constructor(parentContext: BindingContext,

compiler/frontend/src/org/jetbrains/kotlin/resolve/FunctionDescriptorResolver.kt

@@ -122,14 +122,13 @@ class FunctionDescriptorResolver(
         assert(function.typeReference == null) {
             "Return type must be initialized early for function: " + function.text + ", at: " + DiagnosticUtils.atLocation(function) }
 
-        val returnType = if (function.hasBlockBody()) {
-            builtIns.unitType
-        }
-        else if (function.hasBody()) {
-            descriptorResolver.inferReturnTypeFromExpressionBody(trace, scope, dataFlowInfo, function, functionDescriptor)
-        }
-        else {
-            ErrorUtils.createErrorType("No type, no body")
+        val returnType = when {
+            function.hasBlockBody() ->
+                builtIns.unitType
+            function.hasBody() ->
+                descriptorResolver.inferReturnTypeFromExpressionBody(trace, scope, dataFlowInfo, function, functionDescriptor)
+            else ->
+                ErrorUtils.createErrorType("No type, no body")
         }
         functionDescriptor.setReturnType(returnType)
     }

compiler/frontend/src/org/jetbrains/kotlin/resolve/ModifiersChecker.kt

@@ -340,14 +340,10 @@ object ModifierCheckerCore {
                 checkCompatibility(trace, first, second, list.owner, incorrectNodes)
             }
             if (second !in incorrectNodes) {
-                if (!checkTarget(trace, second, actualTargets)) {
-                    incorrectNodes += second
-                }
-                else if (!checkParent(trace, second, parentDescriptor)) {
-                    incorrectNodes += second
-                }
-                else if (!checkLanguageLevelSupport(trace, second, languageVersionSettings, actualTargets)) {
-                    incorrectNodes += second
+                when {
+                    !checkTarget(trace, second, actualTargets) -> incorrectNodes += second
+                    !checkParent(trace, second, parentDescriptor) -> incorrectNodes += second
+                    !checkLanguageLevelSupport(trace, second, languageVersionSettings, actualTargets) -> incorrectNodes += second
                 }
             }
         }

compiler/frontend/src/org/jetbrains/kotlin/resolve/QualifiedExpressionResolver.kt

@@ -568,15 +568,17 @@ class QualifiedExpressionResolver {
     ) {
         if (descriptors.size > 1) {
             val visibleDescriptors = descriptors.filter { isVisible(it, shouldBeVisibleFrom, position) }
-            if (visibleDescriptors.isEmpty()) {
-                val descriptor = descriptors.first() as DeclarationDescriptorWithVisibility
-                trace.report(Errors.INVISIBLE_REFERENCE.on(referenceExpression, descriptor, descriptor.visibility, descriptor))
-            }
-            else if (visibleDescriptors.size > 1) {
-                trace.record(BindingContext.AMBIGUOUS_REFERENCE_TARGET, referenceExpression, visibleDescriptors)
-            }
-            else {
-                storeResult(trace, referenceExpression, visibleDescriptors.single(), null, position, isQualifier)
+            when {
+                visibleDescriptors.isEmpty() -> {
+                    val descriptor = descriptors.first() as DeclarationDescriptorWithVisibility
+                    trace.report(Errors.INVISIBLE_REFERENCE.on(referenceExpression, descriptor, descriptor.visibility, descriptor))
+                }
+                visibleDescriptors.size > 1 -> {
+                    trace.record(BindingContext.AMBIGUOUS_REFERENCE_TARGET, referenceExpression, visibleDescriptors)
+                }
+                else -> {
+                    storeResult(trace, referenceExpression, visibleDescriptors.single(), null, position, isQualifier)
+                }
             }
         }
         else {

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/InlineChecker.kt

@@ -155,21 +155,23 @@ internal class InlineChecker(private val descriptor: FunctionDescriptor) : CallC
 
         val varDescriptor: CallableDescriptor?
         val receiverExpression: KtExpression?
-        if (receiver is ExpressionReceiver) {
-            receiverExpression = receiver.expression
-            varDescriptor = getCalleeDescriptor(context, receiverExpression, true)
-        }
-        else if (receiver is ExtensionReceiver) {
-            val extension = receiver.declarationDescriptor
+        when (receiver) {
+            is ExpressionReceiver -> {
+                receiverExpression = receiver.expression
+                varDescriptor = getCalleeDescriptor(context, receiverExpression, true)
+            }
+            is ExtensionReceiver -> {
+                val extension = receiver.declarationDescriptor
 
-            varDescriptor = extension.extensionReceiverParameter
-            assert(varDescriptor != null) { "Extension should have receiverParameterDescriptor: " + extension }
+                varDescriptor = extension.extensionReceiverParameter
+                assert(varDescriptor != null) { "Extension should have receiverParameterDescriptor: " + extension }
 
-            receiverExpression = expression
-        }
-        else {
-            varDescriptor = null
-            receiverExpression = null
+                receiverExpression = expression
+            }
+            else -> {
+                varDescriptor = null
+                receiverExpression = null
+            }
         }
 
         if (inlinableParameters.contains(varDescriptor)) {

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/resolvedCallUtil.kt

@@ -50,18 +50,18 @@ fun ResolvedCall<*>.hasThisOrNoDispatchReceiver(
     if (resultingDescriptor.dispatchReceiverParameter == null || dispatchReceiverValue == null) return true
 
     var dispatchReceiverDescriptor: DeclarationDescriptor? = null
-    if (dispatchReceiverValue is ImplicitReceiver) {
-        // foo() -- implicit receiver
-        dispatchReceiverDescriptor = dispatchReceiverValue.declarationDescriptor
-    }
-    else if (dispatchReceiverValue is ClassValueReceiver) {
-        dispatchReceiverDescriptor = dispatchReceiverValue.classQualifier.descriptor
-    }
-    else if (dispatchReceiverValue is ExpressionReceiver) {
-        val expression = KtPsiUtil.deparenthesize(dispatchReceiverValue.expression)
-        if (expression is KtThisExpression) {
-            // this.foo() -- explicit receiver
-            dispatchReceiverDescriptor = context.get(BindingContext.REFERENCE_TARGET, expression.instanceReference)
+    when (dispatchReceiverValue) {
+        is ImplicitReceiver -> // foo() -- implicit receiver
+            dispatchReceiverDescriptor = dispatchReceiverValue.declarationDescriptor
+        is ClassValueReceiver -> {
+            dispatchReceiverDescriptor = dispatchReceiverValue.classQualifier.descriptor
+        }
+        is ExpressionReceiver -> {
+            val expression = KtPsiUtil.deparenthesize(dispatchReceiverValue.expression)
+            if (expression is KtThisExpression) {
+                // this.foo() -- explicit receiver
+                dispatchReceiverDescriptor = context.get(BindingContext.REFERENCE_TARGET, expression.instanceReference)
+            }
         }
     }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/DelegatingDataFlowInfo.kt

@@ -283,9 +283,11 @@ internal class DelegatingDataFlowInfo private constructor(
     private fun Set<KotlinType>.containsNothing() = any { KotlinBuiltIns.isNothing(it) }
 
     private fun Set<KotlinType>.intersect(other: Set<KotlinType>) =
-            if (other.containsNothing()) this
-            else if (this.containsNothing()) other
-            else Sets.intersection(this, other)
+            when {
+                other.containsNothing() -> this
+                this.containsNothing() -> other
+                else -> Sets.intersection(this, other)
+            }
 
     override fun or(other: DataFlowInfo): DataFlowInfo {
         if (other === DataFlowInfo.EMPTY) return DataFlowInfo.EMPTY

compiler/frontend/src/org/jetbrains/kotlin/resolve/diagnostics/KotlinSuppressCache.kt

@@ -145,14 +145,10 @@ abstract class KotlinSuppressCache {
         var suppressor: Suppressor? = suppressors[annotated]
         if (suppressor == null) {
             val strings = getSuppressingStrings(annotated)
-            if (strings.isEmpty()) {
-                suppressor = EmptySuppressor(annotated)
-            }
-            else if (strings.size == 1) {
-                suppressor = SingularSuppressor(annotated, strings.iterator().next())
-            }
-            else {
-                suppressor = MultiSuppressor(annotated, strings)
+            suppressor = when {
+                strings.isEmpty() -> EmptySuppressor(annotated)
+                strings.size == 1 -> SingularSuppressor(annotated, strings.iterator().next())
+                else -> MultiSuppressor(annotated, strings)
             }
             suppressors.put(annotated, suppressor)
         }

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/AbstractLazyMemberScope.kt

@@ -169,46 +169,48 @@ protected constructor(
         val declarations = declarationProvider.getDeclarations(kindFilter, nameFilter)
         val result = LinkedHashSet<DeclarationDescriptor>(declarations.size)
         for (declaration in declarations) {
-            if (declaration is KtClassOrObject) {
-                val name = declaration.nameAsSafeName
-                if (nameFilter(name)) {
-                    result.addAll(classDescriptors(name))
+            when (declaration) {
+                is KtClassOrObject -> {
+                    val name = declaration.nameAsSafeName
+                    if (nameFilter(name)) {
+                        result.addAll(classDescriptors(name))
+                    }
                 }
-            }
-            else if (declaration is KtFunction) {
-                val name = declaration.nameAsSafeName
-                if (nameFilter(name)) {
-                    result.addAll(getContributedFunctions(name, location))
+                is KtFunction -> {
+                    val name = declaration.nameAsSafeName
+                    if (nameFilter(name)) {
+                        result.addAll(getContributedFunctions(name, location))
+                    }
                 }
-            }
-            else if (declaration is KtProperty) {
-                val name = declaration.nameAsSafeName
-                if (nameFilter(name)) {
-                    result.addAll(getContributedVariables(name, location))
+                is KtProperty -> {
+                    val name = declaration.nameAsSafeName
+                    if (nameFilter(name)) {
+                        result.addAll(getContributedVariables(name, location))
+                    }
                 }
-            }
-            else if (declaration is KtParameter) {
-                val name = declaration.nameAsSafeName
-                if (nameFilter(name)) {
-                    result.addAll(getContributedVariables(name, location))
+                is KtParameter -> {
+                    val name = declaration.nameAsSafeName
+                    if (nameFilter(name)) {
+                        result.addAll(getContributedVariables(name, location))
+                    }
                 }
-            }
-            else if (declaration is KtTypeAlias) {
-                val name = declaration.nameAsSafeName
-                if (nameFilter(name)) {
-                    result.addAll(getContributedTypeAliasDescriptors(name, location))
+                is KtTypeAlias -> {
+                    val name = declaration.nameAsSafeName
+                    if (nameFilter(name)) {
+                        result.addAll(getContributedTypeAliasDescriptors(name, location))
+                    }
                 }
-            }
-            else if (declaration is KtScript) {
-                val name = declaration.nameAsSafeName
-                if (nameFilter(name)) {
-                    result.addAll(classDescriptors(name))
+                is KtScript -> {
+                    val name = declaration.nameAsSafeName
+                    if (nameFilter(name)) {
+                        result.addAll(classDescriptors(name))
+                    }
                 }
+                is KtDestructuringDeclaration -> {
+                    // MultiDeclarations are not supported on global level
+                }
+                else -> throw IllegalArgumentException("Unsupported declaration kind: " + declaration)
             }
-            else if (declaration is KtDestructuringDeclaration) {
-                // MultiDeclarations are not supported on global level
-            }
-            else throw IllegalArgumentException("Unsupported declaration kind: " + declaration)
         }
         return result.toList()
     }

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

@@ -137,44 +137,45 @@ object LabelResolver {
 
         val declarationsByLabel = context.scope.getDeclarationsByLabel(labelName)
         val size = declarationsByLabel.size
-        if (size == 1) {
-            val declarationDescriptor = declarationsByLabel.single()
-            val thisReceiver = when (declarationDescriptor) {
-                is ClassDescriptor -> declarationDescriptor.thisAsReceiverParameter
-                is FunctionDescriptor -> declarationDescriptor.extensionReceiverParameter
-                is PropertyDescriptor -> declarationDescriptor.extensionReceiverParameter
-                else -> throw UnsupportedOperationException("Unsupported descriptor: " + declarationDescriptor) // TODO
-            }
-
-            val element = DescriptorToSourceUtils.descriptorToDeclaration(declarationDescriptor) ?: error("No PSI element for descriptor: " + declarationDescriptor)
-            context.trace.record(LABEL_TARGET, targetLabel, element)
-            context.trace.record(REFERENCE_TARGET, referenceExpression, declarationDescriptor)
-
-            if (declarationDescriptor is ClassDescriptor) {
-                if (!DescriptorResolver.checkHasOuterClassInstance(context.scope, context.trace, targetLabel, declarationDescriptor)) {
-                    return LabeledReceiverResolutionResult.labelResolutionFailed()
+        when (size) {
+            1 -> {
+                val declarationDescriptor = declarationsByLabel.single()
+                val thisReceiver = when (declarationDescriptor) {
+                    is ClassDescriptor -> declarationDescriptor.thisAsReceiverParameter
+                    is FunctionDescriptor -> declarationDescriptor.extensionReceiverParameter
+                    is PropertyDescriptor -> declarationDescriptor.extensionReceiverParameter
+                    else -> throw UnsupportedOperationException("Unsupported descriptor: " + declarationDescriptor) // TODO
                 }
-            }
 
-            return LabeledReceiverResolutionResult.labelResolutionSuccess(thisReceiver)
-        }
-        else if (size == 0) {
-            val element = resolveNamedLabel(labelName, targetLabel, context.trace)
-            val declarationDescriptor = context.trace.bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, element]
-            if (declarationDescriptor is FunctionDescriptor) {
-                val thisReceiver = declarationDescriptor.extensionReceiverParameter
-                if (thisReceiver != null) {
-                    context.trace.record(LABEL_TARGET, targetLabel, element)
-                    context.trace.record(REFERENCE_TARGET, referenceExpression, declarationDescriptor)
+                val element = DescriptorToSourceUtils.descriptorToDeclaration(declarationDescriptor)
+                              ?: error("No PSI element for descriptor: " + declarationDescriptor)
+                context.trace.record(LABEL_TARGET, targetLabel, element)
+                context.trace.record(REFERENCE_TARGET, referenceExpression, declarationDescriptor)
+
+                if (declarationDescriptor is ClassDescriptor) {
+                    if (!DescriptorResolver.checkHasOuterClassInstance(context.scope, context.trace, targetLabel, declarationDescriptor)) {
+                        return LabeledReceiverResolutionResult.labelResolutionFailed()
+                    }
                 }
+
                 return LabeledReceiverResolutionResult.labelResolutionSuccess(thisReceiver)
             }
-            else {
-                context.trace.report(UNRESOLVED_REFERENCE.on(targetLabel, targetLabel))
+            0 -> {
+                val element = resolveNamedLabel(labelName, targetLabel, context.trace)
+                val declarationDescriptor = context.trace.bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, element]
+                if (declarationDescriptor is FunctionDescriptor) {
+                    val thisReceiver = declarationDescriptor.extensionReceiverParameter
+                    if (thisReceiver != null) {
+                        context.trace.record(LABEL_TARGET, targetLabel, element)
+                        context.trace.record(REFERENCE_TARGET, referenceExpression, declarationDescriptor)
+                    }
+                    return LabeledReceiverResolutionResult.labelResolutionSuccess(thisReceiver)
+                }
+                else {
+                    context.trace.report(UNRESOLVED_REFERENCE.on(targetLabel, targetLabel))
+                }
             }
-        }
-        else {
-            BindingContextUtils.reportAmbiguousLabel(context.trace, targetLabel, declarationsByLabel)
+            else -> BindingContextUtils.reportAmbiguousLabel(context.trace, targetLabel, declarationsByLabel)
         }
         return LabeledReceiverResolutionResult.labelResolutionFailed()
     }

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

@@ -38,9 +38,11 @@ object SenselessComparisonChecker {
             getNullability: (DataFlowValue) -> Nullability
     ) {
         val expr =
-                if (KtPsiUtil.isNullConstant(left)) right
-                else if (KtPsiUtil.isNullConstant(right)) left
-                else return
+                when {
+                    KtPsiUtil.isNullConstant(left) -> right
+                    KtPsiUtil.isNullConstant(right) -> left
+                    else -> return
+                }
 
         val type = getType(expr)
         if (type == null || type.isError) return
@@ -52,10 +54,12 @@ object SenselessComparisonChecker {
         val nullability = getNullability(value)
 
         val expressionIsAlways =
-                if (nullability == Nullability.NULL) equality
-                else if (nullability == Nullability.NOT_NULL) !equality
-                else if (nullability == Nullability.IMPOSSIBLE) false
-                else return
+                when (nullability) {
+                    Nullability.NULL -> equality
+                    Nullability.NOT_NULL -> !equality
+                    Nullability.IMPOSSIBLE -> false
+                    else -> return
+                }
 
         context.trace.report(Errors.SENSELESS_COMPARISON.on(expression, expression, expressionIsAlways))
     }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -632,22 +632,20 @@ class ExpressionCodegen(
 
         val stackElement = data.peek()
 
-        if (stackElement is TryInfo) {
-            //noinspection ConstantConditions
-            genFinallyBlockOrGoto(stackElement, null, afterBreakContinueLabel, data)
-        }
-        else if (stackElement is LoopInfo) {
-            val loop = expression.loop
-            //noinspection ConstantConditions
-            if (loop == stackElement.loop) {
-                val label = if (expression is IrBreak) stackElement.breakLabel else stackElement.continueLabel
-                mv.fixStackAndJump(label)
-                mv.mark(afterBreakContinueLabel)
-                return
+        when (stackElement) {
+            is TryInfo -> //noinspection ConstantConditions
+                genFinallyBlockOrGoto(stackElement, null, afterBreakContinueLabel, data)
+            is LoopInfo -> {
+                val loop = expression.loop
+                //noinspection ConstantConditions
+                if (loop == stackElement.loop) {
+                    val label = if (expression is IrBreak) stackElement.breakLabel else stackElement.continueLabel
+                    mv.fixStackAndJump(label)
+                    mv.mark(afterBreakContinueLabel)
+                    return
+                }
             }
-        }
-        else {
-            throw UnsupportedOperationException("Wrong BlockStackElement in processing stack")
+            else -> throw UnsupportedOperationException("Wrong BlockStackElement in processing stack")
         }
 
         data.pop()
@@ -829,14 +827,12 @@ class ExpressionCodegen(
     private fun doFinallyOnReturn(afterReturnLabel: Label, data: BlockInfo) {
         if (!data.isEmpty()) {
             val stackElement = data.peek()
-            if (stackElement is TryInfo) {
-                genFinallyBlockOrGoto(stackElement, null, afterReturnLabel, data)
-            }
-            else if (stackElement is LoopInfo) {
+            when (stackElement) {
+                is TryInfo -> genFinallyBlockOrGoto(stackElement, null, afterReturnLabel, data)
+                is LoopInfo -> {
 
-            }
-            else {
-                throw UnsupportedOperationException("Wrong BlockStackElement in processing stack")
+                }
+                else -> throw UnsupportedOperationException("Wrong BlockStackElement in processing stack")
             }
 
             data.pop()

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/StatementGenerator.kt

@@ -163,16 +163,18 @@ class StatementGenerator(
             }
             else {
                 val label = expression.getTargetLabel()
-                if (label != null) {
-                    val labelTarget = getOrFail(BindingContext.LABEL_TARGET, label)
-                    val labelTargetDescriptor = getOrFail(BindingContext.DECLARATION_TO_DESCRIPTOR, labelTarget)
-                    labelTargetDescriptor as CallableDescriptor
-                }
-                else if (ExpressionTypingUtils.isFunctionLiteral(scopeOwner)) {
-                    BindingContextUtils.getContainingFunctionSkipFunctionLiterals(scopeOwner, true).first
-                }
-                else {
-                    scopeOwnerAsCallable()
+                when {
+                    label != null -> {
+                        val labelTarget = getOrFail(BindingContext.LABEL_TARGET, label)
+                        val labelTargetDescriptor = getOrFail(BindingContext.DECLARATION_TO_DESCRIPTOR, labelTarget)
+                        labelTargetDescriptor as CallableDescriptor
+                    }
+                    ExpressionTypingUtils.isFunctionLiteral(scopeOwner) -> {
+                        BindingContextUtils.getContainingFunctionSkipFunctionLiterals(scopeOwner, true).first
+                    }
+                    else -> {
+                        scopeOwnerAsCallable()
+                    }
                 }
             }
 

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/tower/ScopeTowerProcessors.kt

@@ -168,25 +168,27 @@ private fun <C : Candidate> createSimpleProcessor(
         classValueReceiver: Boolean,
         collectCandidates: CandidatesCollector
 ) : ScopeTowerProcessor<C> {
-    if (explicitReceiver is ReceiverValueWithSmartCastInfo) {
-        return ExplicitReceiverScopeTowerProcessor(scopeTower, context, explicitReceiver, collectCandidates)
-    }
-    else if (explicitReceiver is QualifierReceiver) {
-        val qualifierProcessor = QualifierScopeTowerProcessor(scopeTower, context, explicitReceiver, collectCandidates)
-        if (!classValueReceiver) return qualifierProcessor
-
-        // todo enum entry, object.
-        val classValue = explicitReceiver.classValueReceiverWithSmartCastInfo ?: return qualifierProcessor
-        return CompositeScopeTowerProcessor(
-                qualifierProcessor,
-                ExplicitReceiverScopeTowerProcessor(scopeTower, context, classValue, collectCandidates)
-        )
-    }
-    else {
-        assert(explicitReceiver == null) {
-            "Illegal explicit receiver: $explicitReceiver(${explicitReceiver!!::class.java.simpleName})"
+    return when (explicitReceiver) {
+        is ReceiverValueWithSmartCastInfo -> {
+            ExplicitReceiverScopeTowerProcessor(scopeTower, context, explicitReceiver, collectCandidates)
+        }
+        is QualifierReceiver -> {
+            val qualifierProcessor = QualifierScopeTowerProcessor(scopeTower, context, explicitReceiver, collectCandidates)
+            if (!classValueReceiver) return qualifierProcessor
+
+            // todo enum entry, object.
+            val classValue = explicitReceiver.classValueReceiverWithSmartCastInfo ?: return qualifierProcessor
+            CompositeScopeTowerProcessor(
+                    qualifierProcessor,
+                    ExplicitReceiverScopeTowerProcessor(scopeTower, context, classValue, collectCandidates)
+            )
+        }
+        else -> {
+            assert(explicitReceiver == null) {
+                "Illegal explicit receiver: $explicitReceiver(${explicitReceiver!!::class.java.simpleName})"
+            }
+            NoExplicitReceiverScopeTowerProcessor(context, collectCandidates)
         }
-        return NoExplicitReceiverScopeTowerProcessor(context, collectCandidates)
     }
 }
 

core/descriptors/src/org/jetbrains/kotlin/types/checker/NewKotlinTypeChecker.kt

@@ -252,19 +252,21 @@ object NewKotlinTypeChecker : KotlinTypeChecker {
         anySupertype(baseType, { false }) {
             val current = captureFromArguments(it, CaptureStatus.FOR_SUBTYPING)
 
-            if (areEqualTypeConstructors(current.constructor, constructor)) {
-                if (result == null) {
-                    result = SmartList()
-                }
-                result!!.add(current)
+            when {
+                areEqualTypeConstructors(current.constructor, constructor) -> {
+                    if (result == null) {
+                        result = SmartList()
+                    }
+                    result!!.add(current)
 
-                SupertypesPolicy.None
-            }
-            else if (current.arguments.isEmpty()) {
-                SupertypesPolicy.LowerIfFlexible
-            }
-            else {
-                SupertypesPolicy.LowerIfFlexibleWithCustomSubstitutor(TypeConstructorSubstitution.create(current).buildSubstitutor())
+                    SupertypesPolicy.None
+                }
+                current.arguments.isEmpty() -> {
+                    SupertypesPolicy.LowerIfFlexible
+                }
+                else -> {
+                    SupertypesPolicy.LowerIfFlexibleWithCustomSubstitutor(TypeConstructorSubstitution.create(current).buildSubstitutor())
+                }
             }
         }
 

core/reflection.jvm/src/kotlin/reflect/jvm/internal/RuntimeTypeMapper.kt

@@ -208,29 +208,33 @@ internal object RuntimeTypeMapper {
 
     fun mapPropertySignature(possiblyOverriddenProperty: PropertyDescriptor): JvmPropertySignature {
         val property = DescriptorUtils.unwrapFakeOverride(possiblyOverriddenProperty).original
-        if (property is DeserializedPropertyDescriptor) {
-            val proto = property.proto
-            if (!proto.hasExtension(JvmProtoBuf.propertySignature)) {
-                // If this property has no JVM signature, it must be from built-ins
-                throw KotlinReflectionInternalError("Reflection on built-in Kotlin types is not yet fully supported. " +
-                                                    "No metadata found for $property")
-            }
-            return JvmPropertySignature.KotlinProperty(
-                    property, proto, proto.getExtension(JvmProtoBuf.propertySignature), property.nameResolver, property.typeTable
-            )
-        }
-        else if (property is JavaPropertyDescriptor) {
-            val element = (property.source as? JavaSourceElement)?.javaElement
-            when (element) {
-                is ReflectJavaField -> return JvmPropertySignature.JavaField(element.member)
-                is ReflectJavaMethod -> return JvmPropertySignature.JavaMethodProperty(
-                        element.member,
-                        ((property.setter?.source as? JavaSourceElement)?.javaElement as? ReflectJavaMethod)?.member
+        return when (property) {
+            is DeserializedPropertyDescriptor -> {
+                val proto = property.proto
+                if (!proto.hasExtension(JvmProtoBuf.propertySignature)) {
+                    // If this property has no JVM signature, it must be from built-ins
+                    throw KotlinReflectionInternalError("Reflection on built-in Kotlin types is not yet fully supported. " +
+                                                        "No metadata found for $property")
+                }
+                JvmPropertySignature.KotlinProperty(
+                        property, proto, proto.getExtension(JvmProtoBuf.propertySignature), property.nameResolver, property.typeTable
                 )
-                else -> throw KotlinReflectionInternalError("Incorrect resolution sequence for Java field $property (source = $element)")
+            }
+            is JavaPropertyDescriptor -> {
+                val element = (property.source as? JavaSourceElement)?.javaElement
+                when (element) {
+                    is ReflectJavaField -> JvmPropertySignature.JavaField(element.member)
+                    is ReflectJavaMethod -> JvmPropertySignature.JavaMethodProperty(
+                            element.member,
+                            ((property.setter?.source as? JavaSourceElement)?.javaElement as? ReflectJavaMethod)?.member
+                    )
+                    else -> throw KotlinReflectionInternalError("Incorrect resolution sequence for Java field $property (source = $element)")
+                }
+            }
+            else -> {
+                throw KotlinReflectionInternalError("Unknown origin of $property (${property.javaClass})")
             }
         }
-        else throw KotlinReflectionInternalError("Unknown origin of $property (${property.javaClass})")
     }
 
     private fun mapIntrinsicFunctionSignature(function: FunctionDescriptor): JvmFunctionSignature? {

eval4j/src/org/jetbrains/eval4j/interpreter.kt

@@ -181,13 +181,10 @@ class SingleInstructionInterpreter(private val eval: Eval) : Interpreter<Value>(
 
             CHECKCAST -> {
                 val targetType = Type.getObjectType((insn as TypeInsnNode).desc)
-                if (value == NULL_VALUE) {
-                    NULL_VALUE
-                } else if (eval.isInstanceOf(value, targetType)) {
-                    ObjectValue(value.obj(), targetType)
-                }
-                else {
-                    throwEvalException(ClassCastException("${value.asmType.className} cannot be cast to ${targetType.className}"))
+                when {
+                    value == NULL_VALUE -> NULL_VALUE
+                    eval.isInstanceOf(value, targetType) -> ObjectValue(value.obj(), targetType)
+                    else -> throwEvalException(ClassCastException("${value.asmType.className} cannot be cast to ${targetType.className}"))
                 }
             }
 

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

@@ -212,14 +212,13 @@ class OptimizedImportsBuilder(
         val explicitImportPath = ImportPath(fqName, false)
         val starImportPath = ImportPath(fqName.parent(), true)
         val importPaths = file.importDirectives.map { it.importPath }
-        if (explicitImportPath in importPaths) {
-            importRules.add(ImportRule.Add(explicitImportPath))
-        }
-        else if (starImportPath in importPaths) {
-            importRules.add(ImportRule.Add(starImportPath))
-        }
-        else { // there is no import for this descriptor in the original import list, so do not allow to import it by star-import
-            importRules.add(ImportRule.DoNotAdd(starImportPath))
+        when {
+            explicitImportPath in importPaths ->
+                importRules.add(ImportRule.Add(explicitImportPath))
+            starImportPath in importPaths ->
+                importRules.add(ImportRule.Add(starImportPath))
+            else -> // there is no import for this descriptor in the original import list, so do not allow to import it by star-import
+                importRules.add(ImportRule.DoNotAdd(starImportPath))
         }
     }
 
@@ -277,14 +276,10 @@ class OptimizedImportsBuilder(
         val iterator1 = tower1.iterator()
         val iterator2 = tower2.iterator()
         while (true) {
-            if (!iterator1.hasNext()) {
-                return !iterator2.hasNext()
-            }
-            else if (!iterator2.hasNext()) {
-                return false
-            }
-            else {
-                if (!areTargetsEqual(iterator1.next(), iterator2.next())) return false
+            when {
+                !iterator1.hasNext() -> return !iterator2.hasNext()
+                !iterator2.hasNext() -> return false
+                else -> if (!areTargetsEqual(iterator1.next(), iterator2.next())) return false
             }
         }
     }

idea/ide-common/src/org/jetbrains/kotlin/resolve/lazy/PartialBodyResolveFilter.kt

@@ -271,18 +271,18 @@ class PartialBodyResolveFilter(
                 val left = condition.left ?: return emptyResult
                 val right = condition.right ?: return emptyResult
 
-                fun smartCastInEq(): Pair<Set<SmartCastName>, Set<SmartCastName>> {
-                    if (left.isNullLiteral()) {
-                        return Pair(setOf(), right.smartCastExpressionName().singletonOrEmptySet())
+                fun smartCastInEq(): Pair<Set<SmartCastName>, Set<SmartCastName>> = when {
+                    left.isNullLiteral() -> {
+                        Pair(setOf(), right.smartCastExpressionName().singletonOrEmptySet())
                     }
-                    else if (right.isNullLiteral()) {
-                        return Pair(setOf(), left.smartCastExpressionName().singletonOrEmptySet())
+                    right.isNullLiteral() -> {
+                        Pair(setOf(), left.smartCastExpressionName().singletonOrEmptySet())
                     }
-                    else {
+                    else -> {
                         val leftName = left.smartCastExpressionName()
                         val rightName = right.smartCastExpressionName()
                         val names = listOfNotNull(leftName, rightName).toSet()
-                        return Pair(names, setOf())
+                        Pair(names, setOf())
                     }
                 }
 

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

@@ -217,26 +217,26 @@ object IDELightClassContexts {
             }
 
             for (declaration in file.declarations) {
-                if (declaration is KtFunction) {
-                    val name = declaration.nameAsSafeName
-                    val functions = packageDescriptor.memberScope.getContributedFunctions(name, NoLookupLocation.FROM_IDE)
-                    for (descriptor in functions) {
-                        ForceResolveUtil.forceResolveAllContents(descriptor)
+                when (declaration) {
+                    is KtFunction -> {
+                        val name = declaration.nameAsSafeName
+                        val functions = packageDescriptor.memberScope.getContributedFunctions(name, NoLookupLocation.FROM_IDE)
+                        for (descriptor in functions) {
+                            ForceResolveUtil.forceResolveAllContents(descriptor)
+                        }
                     }
-                }
-                else if (declaration is KtProperty) {
-                    val name = declaration.nameAsSafeName
-                    val properties = packageDescriptor.memberScope.getContributedVariables(name, NoLookupLocation.FROM_IDE)
-                    for (descriptor in properties) {
-                        ForceResolveUtil.forceResolveAllContents(descriptor)
+                    is KtProperty -> {
+                        val name = declaration.nameAsSafeName
+                        val properties = packageDescriptor.memberScope.getContributedVariables(name, NoLookupLocation.FROM_IDE)
+                        for (descriptor in properties) {
+                            ForceResolveUtil.forceResolveAllContents(descriptor)
+                        }
                     }
-                }
-                else if (declaration is KtClassOrObject || declaration is KtTypeAlias || declaration is KtDestructuringDeclaration) {
-                    // Do nothing: we are not interested in classes or type aliases,
-                    // and all destructuring declarations are erroneous at top level
-                }
-                else {
-                    LOG.error("Unsupported declaration kind: " + declaration + " in file " + file.name + "\n" + file.text)
+                    is KtClassOrObject, is KtTypeAlias, is KtDestructuringDeclaration -> {
+                        // Do nothing: we are not interested in classes or type aliases,
+                        // and all destructuring declarations are erroneous at top level
+                    }
+                    else -> LOG.error("Unsupported declaration kind: " + declaration + " in file " + file.name + "\n" + file.text)
                 }
             }
 

idea/idea-analysis/src/org/jetbrains/kotlin/idea/findUsages/UsageTypeUtils.kt

@@ -101,11 +101,18 @@ object UsageTypeUtils {
                     CLASS_CAST_TO
 
                 with(refExpr.getNonStrictParentOfType<KtDotQualifiedExpression>()) {
-                    if (this == null) false
-                    else if (receiverExpression == refExpr) true
-                    else
-                        selectorExpression == refExpr
-                        && getParentOfTypeAndBranch<KtDotQualifiedExpression>(strict = true) { receiverExpression } != null
+                    when {
+                        this == null -> {
+                            false
+                        }
+                        receiverExpression == refExpr -> {
+                            true
+                        }
+                        else -> {
+                            selectorExpression == refExpr
+                            && getParentOfTypeAndBranch<KtDotQualifiedExpression>(strict = true) { receiverExpression } != null
+                        }
+                    }
                 } ->
                     CLASS_OBJECT_ACCESS
 

idea/idea-analysis/src/org/jetbrains/kotlin/idea/framework/CommonLibraryDetectionUtil.kt

@@ -49,12 +49,11 @@ object CommonLibraryDetectionUtil {
 
             var platform: TargetPlatform? = null
             VfsUtilCore.processFilesRecursively(root) { file ->
-                if (file.fileType == JavaClassFileType.INSTANCE)
-                    platform = JvmPlatform
-                else if (isKotlinMetadataFile(file))
-                    platform = TargetPlatform.Default
-                else if (KotlinJavaScriptLibraryDetectionUtil.isJsFileWithMetadata(file))
-                    platform = JsPlatform
+                when {
+                    file.fileType == JavaClassFileType.INSTANCE -> platform = JvmPlatform
+                    isKotlinMetadataFile(file) -> platform = TargetPlatform.Default
+                    KotlinJavaScriptLibraryDetectionUtil.isJsFileWithMetadata(file) -> platform = JsPlatform
+                }
 
                 platform == null
             }

idea/idea-analysis/src/org/jetbrains/kotlin/idea/quickfix/KotlinSuppressIntentionAction.kt

@@ -129,16 +129,12 @@ class KotlinSuppressIntentionAction private constructor(
         val args = entry.valueArgumentList
         val psiFactory = KtPsiFactory(entry)
         val newArgList = psiFactory.createCallArguments("($id)")
-        if (args == null) {
-            // new argument list
-            entry.addAfter(newArgList, entry.lastChild)
-        }
-        else if (args.arguments.isEmpty()) {
-            // replace '()' with a new argument list
-            args.replace(newArgList)
-        }
-        else {
-            args.addArgument(newArgList.arguments[0])
+        when {
+            args == null -> // new argument list
+                entry.addAfter(newArgList, entry.lastChild)
+            args.arguments.isEmpty() -> // replace '()' with a new argument list
+                args.replace(newArgList)
+            else -> args.addArgument(newArgList.arguments[0])
         }
     }
 

idea/idea-analysis/src/org/jetbrains/kotlin/idea/search/PsiBasedClassResolver.kt

@@ -151,14 +151,10 @@ class PsiBasedClassResolver @TestOnly constructor(private val targetClassFqName:
         val file = ref.containingKtFile
         var result: Result = Result.NothingFound
         val filePackage = file.packageFqName.asString()
-        if (filePackage == targetPackage) {
-            result = result.changeTo(Result.Found)
-        }
-        else if (filePackage in conflictingPackages) {
-            result = result.changeTo(Result.FoundOther)
-        }
-        else if (filePackage in packagesWithTypeAliases) {
-            return UNSURE
+        when (filePackage) {
+            targetPackage -> result = result.changeTo(Result.Found)
+            in conflictingPackages -> result = result.changeTo(Result.FoundOther)
+            in packagesWithTypeAliases -> return UNSURE
         }
 
         for (importPath in file.getDefaultImports()) {
@@ -202,14 +198,10 @@ class PsiBasedClassResolver @TestOnly constructor(private val targetClassFqName:
             }
         }
         else {
-            if (qName?.asString() == targetPackage) {
-                return result.changeTo(Result.Found)
-            }
-            else if (qName?.asString() in conflictingPackages) {
-                return result.changeTo(Result.FoundOther)
-            }
-            else if (qName?.asString() in packagesWithTypeAliases) {
-                return Result.Ambiguity
+            when {
+                qName?.asString() == targetPackage -> return result.changeTo(Result.Found)
+                qName?.asString() in conflictingPackages -> return result.changeTo(Result.FoundOther)
+                qName?.asString() in packagesWithTypeAliases -> return Result.Ambiguity
             }
         }
         return result

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

@@ -276,12 +276,11 @@ class BasicLookupElementFactory(
                 appendTailText(" for $receiverPresentation")
 
                 val container = descriptor.containingDeclaration
-                val containerPresentation = if (container is ClassDescriptor)
-                    DescriptorUtils.getFqNameFromTopLevelClass(container).toString()
-                else if (container is PackageFragmentDescriptor)
-                    container.fqName.toString()
-                else
-                    null
+                val containerPresentation = when (container) {
+                    is ClassDescriptor -> DescriptorUtils.getFqNameFromTopLevelClass(container).toString()
+                    is PackageFragmentDescriptor -> container.fqName.toString()
+                    else -> null
+                }
                 if (containerPresentation != null) {
                     appendTailText(" in $containerPresentation")
                 }

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

@@ -96,32 +96,29 @@ class CompletionBindingContextProvider(project: Project) {
         val psiElementsBeforeAndAfter = modificationScope?.let { collectPsiElementsBeforeAndAfter(modificationScope, inStatement) }
 
         val prevCompletionData = prevCompletionDataCache.value.data
-        if (prevCompletionData == null) {
-            log("No up-to-date data from previous completion\n")
-        }
-        else if (block != prevCompletionData.block) {
-            log("Not in the same block\n")
-        }
-        else if (prevStatement != prevCompletionData.prevStatement) {
-            log("Previous statement is not the same\n")
-        }
-        else if (psiElementsBeforeAndAfter != prevCompletionData.psiElementsBeforeAndAfter) {
-            log("PSI-tree has changed inside current scope\n")
-        }
-        else if (inStatement.isTooComplex()) {
-            log("Current statement is too complex to use optimization\n")
-        }
-        else {
-            log("Statement position is the same - analyzing only one statement:\n${inStatement.text.prependIndent("    ")}\n")
-            LOG.debug("Reusing data from completion of \"${prevCompletionData.debugText}\"")
+        when {
+            prevCompletionData == null ->
+                log("No up-to-date data from previous completion\n")
+            block != prevCompletionData.block ->
+                log("Not in the same block\n")
+            prevStatement != prevCompletionData.prevStatement ->
+                log("Previous statement is not the same\n")
+            psiElementsBeforeAndAfter != prevCompletionData.psiElementsBeforeAndAfter ->
+                log("PSI-tree has changed inside current scope\n")
+            inStatement.isTooComplex() ->
+                log("Current statement is too complex to use optimization\n")
+            else -> {
+                log("Statement position is the same - analyzing only one statement:\n${inStatement.text.prependIndent("    ")}\n")
+                LOG.debug("Reusing data from completion of \"${prevCompletionData.debugText}\"")
 
-            //TODO: expected type?
-            val statementContext = inStatement.analyzeInContext(scope = prevCompletionData.statementResolutionScope,
-                                                                contextExpression = block,
-                                                                dataFlowInfo = prevCompletionData.statementDataFlowInfo,
-                                                                isStatement = true)
-            // we do not update prevCompletionDataCache because the same data should work
-            return CompositeBindingContext.create(listOf(statementContext, prevCompletionData.bindingContext))
+                //TODO: expected type?
+                val statementContext = inStatement.analyzeInContext(scope = prevCompletionData.statementResolutionScope,
+                                                                    contextExpression = block,
+                                                                    dataFlowInfo = prevCompletionData.statementDataFlowInfo,
+                                                                    isStatement = true)
+                // we do not update prevCompletionDataCache because the same data should work
+                return CompositeBindingContext.create(listOf(statementContext, prevCompletionData.bindingContext))
+            }
         }
 
         val bindingContext = resolutionFacade.analyze(position.parentsWithSelf.firstIsInstance<KtElement>(), BodyResolveMode.PARTIAL_FOR_COMPLETION)

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

@@ -381,20 +381,17 @@ class LookupElementFactory(
         return CallableWeight(bestWeight, receiverIndexToUse)
     }
 
-    private fun CallableDescriptor.callableWeightForReceiverType(receiverType: KotlinType, receiverParameterType: KotlinType): CallableWeightEnum? {
-        if (TypeUtils.equalTypes(receiverType, receiverParameterType)) {
-            return when {
-                isExtensionForTypeParameter() -> CallableWeightEnum.typeParameterExtension
-                isExtension -> CallableWeightEnum.thisTypeExtension
-                else -> CallableWeightEnum.thisClassMember
-            }
-        }
-        else if (receiverType.isSubtypeOf(receiverParameterType)) {
-            return if (isExtension) CallableWeightEnum.baseTypeExtension else CallableWeightEnum.baseClassMember
-        }
-        else {
-            return null
+    private fun CallableDescriptor.callableWeightForReceiverType(
+            receiverType: KotlinType,
+            receiverParameterType: KotlinType
+    ): CallableWeightEnum? = when {
+        TypeUtils.equalTypes(receiverType, receiverParameterType) -> when {
+            isExtensionForTypeParameter() -> CallableWeightEnum.typeParameterExtension
+            isExtension -> CallableWeightEnum.thisTypeExtension
+            else -> CallableWeightEnum.thisClassMember
         }
+        receiverType.isSubtypeOf(receiverParameterType) -> if (isExtension) CallableWeightEnum.baseTypeExtension else CallableWeightEnum.baseClassMember
+        else -> null
     }
 
     private fun CallableDescriptor.isExtensionForTypeParameter(): Boolean {

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

@@ -343,12 +343,11 @@ class ExpectedInfos(
         }
 
         val tail = if (argumentName == null) {
-            if (parameter == parameters.last())
-                rparenthTail
-            else if (parameters.dropWhile { it != parameter }.drop(1).any(::needCommaForParameter))
-                Tail.COMMA
-            else
-                null
+            when {
+                parameter == parameters.last() -> rparenthTail
+                parameters.dropWhile { it != parameter }.drop(1).any(::needCommaForParameter) -> Tail.COMMA
+                else -> null
+            }
         }
         else {
             namedArgumentTail(argumentToParameter, argumentName, descriptor)
@@ -404,12 +403,11 @@ class ExpectedInfos(
     private fun namedArgumentTail(argumentToParameter: Map<ValueArgument, ValueParameterDescriptor>, argumentName: Name, descriptor: FunctionDescriptor): Tail? {
         val usedParameterNames = (argumentToParameter.values.map { it.name } + listOf(argumentName)).toSet()
         val notUsedParameters = descriptor.valueParameters.filter { it.name !in usedParameterNames }
-        return if (notUsedParameters.isEmpty())
-            Tail.RPARENTH // named arguments no supported for []
-        else if (notUsedParameters.all { it.hasDefaultValue() })
-            null
-        else
-            Tail.COMMA
+        return when {
+            notUsedParameters.isEmpty() -> Tail.RPARENTH // named arguments no supported for []
+            notUsedParameters.all { it.hasDefaultValue() } -> null
+            else -> Tail.COMMA
+        }
     }
 
     private fun calculateForEqAndAssignment(expressionWithType: KtExpression): Collection<ExpectedInfo>? {

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

@@ -35,15 +35,14 @@ class ImportableFqNameClassifier(private val file: KtFile) {
         for (import in file.importDirectives) {
             val importPath = import.importPath ?: continue
             val fqName = importPath.fqName
-            if (importPath.isAllUnder) {
-                allUnderImports.add(fqName)
-            }
-            else if (!importPath.hasAlias()) {
-                preciseImports.add(fqName)
-                preciseImportPackages.add(fqName.parent())
-            } else {
-                excludedImports.add(fqName)
-                // TODO: support aliased imports in completion
+            when {
+                importPath.isAllUnder -> allUnderImports.add(fqName)
+                !importPath.hasAlias() -> {
+                    preciseImports.add(fqName)
+                    preciseImportPackages.add(fqName.parent())
+                }
+                else -> excludedImports.add(fqName)
+            // TODO: support aliased imports in completion
             }
         }
     }

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

@@ -174,79 +174,45 @@ object KotlinNameSuggester {
         val typeChecker = KotlinTypeChecker.DEFAULT
         if (ErrorUtils.containsErrorType(type)) return
 
-        if (typeChecker.equalTypes(builtIns.booleanType, type)) {
-            addName("b", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.intType, type)) {
-            addName("i", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.byteType, type)) {
-            addName("byte", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.longType, type)) {
-            addName("l", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.floatType, type)) {
-            addName("fl", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.doubleType, type)) {
-            addName("d", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.shortType, type)) {
-            addName("sh", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.charType, type)) {
-            addName("c", validator)
-        }
-        else if (typeChecker.equalTypes(builtIns.stringType, type)) {
-            addName("s", validator)
-        }
-        else if (KotlinBuiltIns.isArray(type) || KotlinBuiltIns.isPrimitiveArray(type)) {
-            val elementType = builtIns.getArrayElementType(type)
-            if (typeChecker.equalTypes(builtIns.booleanType, elementType)) {
-                addName("booleans", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.intType, elementType)) {
-                addName("ints", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.byteType, elementType)) {
-                addName("bytes", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.longType, elementType)) {
-                addName("longs", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.floatType, elementType)) {
-                addName("floats", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.doubleType, elementType)) {
-                addName("doubles", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.shortType, elementType)) {
-                addName("shorts", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.charType, elementType)) {
-                addName("chars", validator)
-            }
-            else if (typeChecker.equalTypes(builtIns.stringType, elementType)) {
-                addName("strings", validator)
-            }
-            else {
-                val classDescriptor = TypeUtils.getClassDescriptor(elementType)
-                if (classDescriptor != null) {
-                    val className = classDescriptor.name
-                    addName("arrayOf" + StringUtil.capitalize(className.asString()) + "s", validator)
+        when {
+            typeChecker.equalTypes(builtIns.booleanType, type) -> addName("b", validator)
+            typeChecker.equalTypes(builtIns.intType, type) -> addName("i", validator)
+            typeChecker.equalTypes(builtIns.byteType, type) -> addName("byte", validator)
+            typeChecker.equalTypes(builtIns.longType, type) -> addName("l", validator)
+            typeChecker.equalTypes(builtIns.floatType, type) -> addName("fl", validator)
+            typeChecker.equalTypes(builtIns.doubleType, type) -> addName("d", validator)
+            typeChecker.equalTypes(builtIns.shortType, type) -> addName("sh", validator)
+            typeChecker.equalTypes(builtIns.charType, type) -> addName("c", validator)
+            typeChecker.equalTypes(builtIns.stringType, type) -> addName("s", validator)
+            KotlinBuiltIns.isArray(type) || KotlinBuiltIns.isPrimitiveArray(type) -> {
+                val elementType = builtIns.getArrayElementType(type)
+                when {
+                    typeChecker.equalTypes(builtIns.booleanType, elementType) -> addName("booleans", validator)
+                    typeChecker.equalTypes(builtIns.intType, elementType) -> addName("ints", validator)
+                    typeChecker.equalTypes(builtIns.byteType, elementType) -> addName("bytes", validator)
+                    typeChecker.equalTypes(builtIns.longType, elementType) -> addName("longs", validator)
+                    typeChecker.equalTypes(builtIns.floatType, elementType) -> addName("floats", validator)
+                    typeChecker.equalTypes(builtIns.doubleType, elementType) -> addName("doubles", validator)
+                    typeChecker.equalTypes(builtIns.shortType, elementType) -> addName("shorts", validator)
+                    typeChecker.equalTypes(builtIns.charType, elementType) -> addName("chars", validator)
+                    typeChecker.equalTypes(builtIns.stringType, elementType) -> addName("strings", validator)
+                    else -> {
+                        val classDescriptor = TypeUtils.getClassDescriptor(elementType)
+                        if (classDescriptor != null) {
+                            val className = classDescriptor.name
+                            addName("arrayOf" + StringUtil.capitalize(className.asString()) + "s", validator)
+                        }
+                    }
                 }
             }
-        }
-        else if (type.isFunctionType) {
-            addName("function", validator)
-        }
-        else {
-            val descriptor = type.constructor.declarationDescriptor
-            if (descriptor != null) {
-                val className = descriptor.name
-                if (!className.isSpecial) {
-                    addCamelNames(className.asString(), validator)
+            type.isFunctionType -> addName("function", validator)
+            else -> {
+                val descriptor = type.constructor.declarationDescriptor
+                if (descriptor != null) {
+                    val className = descriptor.name
+                    if (!className.isSpecial) {
+                        addCamelNames(className.asString(), validator)
+                    }
                 }
             }
         }

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

@@ -204,25 +204,24 @@ fun KtModifierListOwner.setVisibility(visibilityModifier: KtModifierKeywordToken
 }
 
 fun KtDeclaration.implicitVisibility(): KtModifierKeywordToken? =
-        if (this is KtConstructor<*>) {
-            val klass = getContainingClassOrObject()
-            if (klass is KtClass && (klass.isEnum() || klass.isSealed())) KtTokens.PRIVATE_KEYWORD
-            else KtTokens.DEFAULT_VISIBILITY_KEYWORD
-        }
-        else if (hasModifier(KtTokens.OVERRIDE_KEYWORD)) {
-            (resolveToDescriptor(BodyResolveMode.PARTIAL) as? CallableMemberDescriptor)
-                    ?.overriddenDescriptors
-                    ?.let { OverridingUtil.findMaxVisibility(it) }
-                    ?.toKeywordToken()
-        }
-        else {
-            KtTokens.DEFAULT_VISIBILITY_KEYWORD
+        when {
+            this is KtConstructor<*> -> {
+                val klass = getContainingClassOrObject()
+                if (klass is KtClass && (klass.isEnum() || klass.isSealed())) KtTokens.PRIVATE_KEYWORD
+                else KtTokens.DEFAULT_VISIBILITY_KEYWORD
+            }
+            hasModifier(KtTokens.OVERRIDE_KEYWORD) -> {
+                (resolveToDescriptor(BodyResolveMode.PARTIAL) as? CallableMemberDescriptor)
+                        ?.overriddenDescriptors
+                        ?.let { OverridingUtil.findMaxVisibility(it) }
+                        ?.toKeywordToken()
+            }
+            else -> {
+                KtTokens.DEFAULT_VISIBILITY_KEYWORD
+            }
         }
 
-fun KtModifierListOwner.canBePrivate(): Boolean {
-    if (modifierList?.hasModifier(KtTokens.ABSTRACT_KEYWORD) ?: false) return false
-    return true
-}
+fun KtModifierListOwner.canBePrivate() = modifierList?.hasModifier(KtTokens.ABSTRACT_KEYWORD) != true
 
 fun KtModifierListOwner.canBeProtected(): Boolean {
     val parent = this.parent

idea/idea-maven/src/org/jetbrains/kotlin/idea/maven/actions/MavenPluginSourcesSwap.kt

@@ -75,12 +75,12 @@ class MavenPluginSourcesMoveToExecutionIntention : PsiElementBaseIntentionAction
         val domElement = DomManager.getDomManager(project).getDomElement(tag) as? GenericDomValue<*> ?: return
         val dir = domElement.rawText ?: return
 
-        val relevantExecutions = if (domElement.getParentOfType(MavenDomBuild::class.java, false)?.sourceDirectory === domElement) {
-            pomFile.findKotlinExecutions(PomFile.KotlinGoals.Compile, PomFile.KotlinGoals.Js)
-        } else if (domElement.getParentOfType(MavenDomBuild::class.java, false)?.testSourceDirectory === domElement) {
-            pomFile.findKotlinExecutions(PomFile.KotlinGoals.TestCompile, PomFile.KotlinGoals.TestJs)
-        } else {
-            emptyList()
+        val relevantExecutions = when {
+            domElement.getParentOfType(MavenDomBuild::class.java, false)?.sourceDirectory === domElement ->
+                pomFile.findKotlinExecutions(PomFile.KotlinGoals.Compile, PomFile.KotlinGoals.Js)
+            domElement.getParentOfType(MavenDomBuild::class.java, false)?.testSourceDirectory === domElement ->
+                pomFile.findKotlinExecutions(PomFile.KotlinGoals.TestCompile, PomFile.KotlinGoals.TestJs)
+            else -> emptyList()
         }
 
         if (relevantExecutions.isNotEmpty()) {

idea/src/org/jetbrains/kotlin/idea/configuration/KotlinWithLibraryConfigurator.kt

@@ -263,19 +263,11 @@ abstract class KotlinWithLibraryConfigurator internal constructor() : KotlinProj
             targetFile: File,
             jarType: OrderRootType,
             useBundled: Boolean
-    ): FileState {
-        if (targetFile.exists()) {
-            return FileState.EXISTS
-        }
-        else if (getPathFromLibrary(project, jarType) != null) {
-            return FileState.COPY
-        }
-        else if (useBundled) {
-            return FileState.DO_NOT_COPY
-        }
-        else {
-            return FileState.COPY
-        }
+    ): FileState = when {
+        targetFile.exists() -> FileState.EXISTS
+        getPathFromLibrary(project, jarType) != null -> FileState.COPY
+        useBundled -> FileState.DO_NOT_COPY
+        else -> FileState.COPY
     }
 
     private fun getPathToCopyFileTo(

idea/src/org/jetbrains/kotlin/idea/debugger/DebuggerClassNameProvider.kt

@@ -120,26 +120,27 @@ class DebuggerClassNameProvider(
             }
             is KtClassOrObject -> {
                 val enclosingElementForLocal = runReadAction { KtPsiUtil.getEnclosingElementForLocalDeclaration(element) }
-                if (enclosingElementForLocal != null) { // A local class
-                    getOuterClassNamesForElement(enclosingElementForLocal)
-                }
-                else if (runReadAction { element.isObjectLiteral() }) {
-                    getOuterClassNamesForElement(element.relevantParentInReadAction)
-                }
-                else { // Guaranteed to be non-local class or object
-                    element.readAction {
-                        if (it is KtClass && runReadAction { it.isInterface() }) {
-                            val name = getNameForNonLocalClass(it)
+                when {
+                    enclosingElementForLocal != null ->
+                        // A local class
+                        getOuterClassNamesForElement(enclosingElementForLocal)
+                    runReadAction { element.isObjectLiteral() } ->
+                        getOuterClassNamesForElement(element.relevantParentInReadAction)
+                    else ->
+                        // Guaranteed to be non-local class or object
+                        element.readAction {
+                            if (it is KtClass && runReadAction { it.isInterface() }) {
+                                val name = getNameForNonLocalClass(it)
 
-                            if (name != null)
-                                Cached(listOf(name, name + JvmAbi.DEFAULT_IMPLS_SUFFIX))
-                            else
-                                ComputedClassNames.EMPTY
+                                if (name != null)
+                                    Cached(listOf(name, name + JvmAbi.DEFAULT_IMPLS_SUFFIX))
+                                else
+                                    ComputedClassNames.EMPTY
+                            }
+                            else {
+                                getNameForNonLocalClass(it)?.let { ComputedClassNames.Cached(it) } ?: ComputedClassNames.EMPTY
+                            }
                         }
-                        else {
-                            getNameForNonLocalClass(it)?.let { ComputedClassNames.Cached(it) } ?: ComputedClassNames.EMPTY
-                        }
-                    }
                 }
             }
             is KtProperty -> {

idea/src/org/jetbrains/kotlin/idea/debugger/evaluate/KotlinEvaluationBuilder.kt

@@ -300,14 +300,13 @@ class KotlinEvaluator(val codeFragment: KtCodeFragment, val sourcePosition: Sour
             val jdiValue = when (this) {
                 is ValueReturned -> result
                 is ExceptionThrown -> {
-                    if (this.kind == ExceptionThrown.ExceptionKind.FROM_EVALUATED_CODE) {
-                        exception(InvocationException(this.exception.value as ObjectReference))
-                    }
-                    else if (this.kind == ExceptionThrown.ExceptionKind.BROKEN_CODE) {
-                        throw exception.value as Throwable
-                    }
-                    else {
-                        exception(exception.toString())
+                    when {
+                        this.kind == ExceptionThrown.ExceptionKind.FROM_EVALUATED_CODE ->
+                            exception(InvocationException(this.exception.value as ObjectReference))
+                        this.kind == ExceptionThrown.ExceptionKind.BROKEN_CODE ->
+                            throw exception.value as Throwable
+                        else ->
+                            exception(exception.toString())
                     }
                 }
                 is AbnormalTermination -> exception(message)

idea/src/org/jetbrains/kotlin/idea/editor/KotlinLiteralCopyPasteProcessor.kt

@@ -187,33 +187,33 @@ private class TemplateTokenSequence(private val inputString: String) : Sequence<
         val wrapped = '"' + input.substring(from) + '"'
         val lexer = KotlinLexer().apply { start(wrapped) }.apply { advance() }
 
-        if (lexer.tokenType == KtTokens.SHORT_TEMPLATE_ENTRY_START) {
-            lexer.advance()
-            return if (lexer.tokenType == KtTokens.IDENTIFIER) {
-                from + lexer.tokenEnd - 1
-            }
-            else {
-                -1
-            }
-        }
-        else if (lexer.tokenType == KtTokens.LONG_TEMPLATE_ENTRY_START) {
-            var depth = 0
-            while (lexer.tokenType != null) {
-                if (lexer.tokenType == KtTokens.LONG_TEMPLATE_ENTRY_START) {
-                    depth++
-                }
-                else if (lexer.tokenType == KtTokens.LONG_TEMPLATE_ENTRY_END) {
-                    depth--
-                    if (depth == 0) {
-                        return from + lexer.currentPosition.offset
-                    }
-                }
+        when (lexer.tokenType) {
+            KtTokens.SHORT_TEMPLATE_ENTRY_START -> {
                 lexer.advance()
+                return if (lexer.tokenType == KtTokens.IDENTIFIER) {
+                    from + lexer.tokenEnd - 1
+                }
+                else {
+                    -1
+                }
             }
-            return -1
-        }
-        else {
-            return -1
+            KtTokens.LONG_TEMPLATE_ENTRY_START -> {
+                var depth = 0
+                while (lexer.tokenType != null) {
+                    if (lexer.tokenType == KtTokens.LONG_TEMPLATE_ENTRY_START) {
+                        depth++
+                    }
+                    else if (lexer.tokenType == KtTokens.LONG_TEMPLATE_ENTRY_END) {
+                        depth--
+                        if (depth == 0) {
+                            return from + lexer.currentPosition.offset
+                        }
+                    }
+                    lexer.advance()
+                }
+                return -1
+            }
+            else -> return -1
         }
     }
 

idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinRainbowVisitor.kt

@@ -40,32 +40,34 @@ class KotlinRainbowVisitor : RainbowVisitor() {
     override fun clone() = KotlinRainbowVisitor()
 
     override fun visit(element: PsiElement) {
-        if (element.isRainbowDeclaration()) {
-            val rainbowElement = (element as KtNamedDeclaration).nameIdentifier ?: return
-            addRainbowHighlight(element, rainbowElement)
-        }
-        else if (element is KtSimpleNameExpression) {
-            val qualifiedExpression = PsiTreeUtil.getParentOfType(element, KtQualifiedExpression::class.java, true,
-                                                                  KtLambdaExpression::class.java, KtValueArgumentList::class.java)
-            if (qualifiedExpression?.selectorExpression?.isAncestor(element) == true) return
+        when {
+            element.isRainbowDeclaration() -> {
+                val rainbowElement = (element as KtNamedDeclaration).nameIdentifier ?: return
+                addRainbowHighlight(element, rainbowElement)
+            }
+            element is KtSimpleNameExpression -> {
+                val qualifiedExpression = PsiTreeUtil.getParentOfType(element, KtQualifiedExpression::class.java, true,
+                                                                      KtLambdaExpression::class.java, KtValueArgumentList::class.java)
+                if (qualifiedExpression?.selectorExpression?.isAncestor(element) == true) return
 
-            val bindingContext = element.analyze(BodyResolveMode.PARTIAL_WITH_DIAGNOSTICS)
-            val targets = element.getReferenceTargets(bindingContext)
-            val targetVariable = targets.firstIsInstanceOrNull<VariableDescriptor>()
-            if (targetVariable != null) {
-                val targetElement = DescriptorToSourceUtils.getSourceFromDescriptor(targetVariable)
-                if (targetElement.isRainbowDeclaration()) {
-                    addRainbowHighlight(targetElement!!, element)
-                }
-                else if (targetElement == null && element.getReferencedName() == "it") {
-                    addRainbowHighlight(element, element)
+                val bindingContext = element.analyze(BodyResolveMode.PARTIAL_WITH_DIAGNOSTICS)
+                val targets = element.getReferenceTargets(bindingContext)
+                val targetVariable = targets.firstIsInstanceOrNull<VariableDescriptor>()
+                if (targetVariable != null) {
+                    val targetElement = DescriptorToSourceUtils.getSourceFromDescriptor(targetVariable)
+                    if (targetElement.isRainbowDeclaration()) {
+                        addRainbowHighlight(targetElement!!, element)
+                    }
+                    else if (targetElement == null && element.getReferencedName() == "it") {
+                        addRainbowHighlight(element, element)
+                    }
                 }
             }
-        }
-        else if (element is KDocName) {
-            val target = element.reference?.resolve() ?: return
-            if (target.isRainbowDeclaration()) {
-                addRainbowHighlight(target, element, KDOC_LINK)
+            element is KDocName -> {
+                val target = element.reference?.resolve() ?: return
+                if (target.isRainbowDeclaration()) {
+                    addRainbowHighlight(target, element, KDOC_LINK)
+                }
             }
         }
     }

idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt

@@ -95,14 +95,10 @@ class KotlinUnusedImportInspection : AbstractKotlinInspection() {
                 val importPath = directive.importPath ?: continue
                 if (importPath.alias != null) continue // highlighting of unused alias imports not supported yet
 
-                val isUsed = if (!importPaths.add(importPath)) {
-                    false
-                }
-                else if (importPath.isAllUnder) {
-                    importPath.fqName in parentFqNames
-                }
-                else {
-                    importPath.fqName in fqNames
+                val isUsed = when {
+                    !importPaths.add(importPath) -> false
+                    importPath.isAllUnder -> importPath.fqName in parentFqNames
+                    else -> importPath.fqName in fqNames
                 }
 
                 if (!isUsed) {

idea/src/org/jetbrains/kotlin/idea/inspections/NullableBooleanElvisInspection.kt

@@ -72,7 +72,11 @@ class NullableBooleanElvisInspection : AbstractKotlinInspection(), CleanupLocalI
             val constPart = element.right as? KtConstantExpression ?: return
             val exprPart = element.left ?: return
 
-            val constValue = if (KtPsiUtil.isTrueConstant(constPart)) true else if (KtPsiUtil.isFalseConstant(constPart)) false else return
+            val constValue = when {
+                KtPsiUtil.isTrueConstant(constPart) -> true
+                KtPsiUtil.isFalseConstant(constPart) -> false
+                else -> return
+            }
             val equalityCheckExpression = element.replaced(KtPsiFactory(constPart).buildExpression {
                 appendExpression(exprPart)
                 appendFixedText(if (constValue) " != false" else " == true")

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

@@ -47,7 +47,11 @@ class NullableBooleanEqualityCheckToElvisIntention : SelfTargetingIntention<KtBi
         val constPart = element.left as? KtConstantExpression ?:
                         element.right as? KtConstantExpression ?: return
         val exprPart = (if (element.right == constPart) element.left else element.right) ?: return
-        val constValue = if (KtPsiUtil.isTrueConstant(constPart)) true else if (KtPsiUtil.isFalseConstant(constPart)) false else return
+        val constValue = when {
+            KtPsiUtil.isTrueConstant(constPart) -> true
+            KtPsiUtil.isFalseConstant(constPart) -> false
+            else -> return
+        }
 
         val factory = KtPsiFactory(constPart)
         val elvis = factory.createExpressionByPattern("$0 ?: ${!constValue}", exprPart)

idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/IfThenUtils.kt

@@ -168,14 +168,11 @@ data class IfThenToSelectData(
             if (condition is KtIsExpression) newReceiver!! else baseClause
         }
         else {
-            if (condition is KtIsExpression) {
-                (baseClause as KtDotQualifiedExpression).replaceFirstReceiver(
+            when {
+                condition is KtIsExpression -> (baseClause as KtDotQualifiedExpression).replaceFirstReceiver(
                         factory, newReceiver!!, safeAccess = true)
-            }
-            else if (hasImplicitReceiver()) {
-                factory.createExpressionByPattern("this?.$0", baseClause).insertSafeCalls(factory)
-            } else {
-                baseClause.insertSafeCalls(factory)
+                hasImplicitReceiver() -> factory.createExpressionByPattern("this?.$0", baseClause).insertSafeCalls(factory)
+                else -> baseClause.insertSafeCalls(factory)
             }
         }
     }

idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/result/MaxOrMinTransformation.kt

@@ -116,14 +116,10 @@ class MaxOrMinTransformation(
             val functionName = if (isMax) "max" else "min"
             val arguments = assignment.right.extractStaticFunctionCallArguments("java.lang.Math." + functionName) ?: return null
             if (arguments.size != 2) return null
-            val value = if (arguments[0].isVariableReference(variableInitialization.variable)) {
-                arguments[1] ?: return null
-            }
-            else if (arguments[1].isVariableReference(variableInitialization.variable)) {
-                arguments[0] ?: return null
-            }
-            else {
-                return null
+            val value = when {
+                arguments[0].isVariableReference(variableInitialization.variable) -> arguments[1] ?: return null
+                arguments[1].isVariableReference(variableInitialization.variable) -> arguments[0] ?: return null
+                else -> return null
             }
 
             val mapTransformation = if (value.isVariableReference(state.inputVariable))
@@ -148,14 +144,10 @@ class MaxOrMinTransformation(
             if (comparison !in setOf(KtTokens.GT, KtTokens.LT, KtTokens.GTEQ, KtTokens.LTEQ)) return null
             val left = condition.left as? KtNameReferenceExpression ?: return null
             val right = condition.right as? KtNameReferenceExpression ?: return null
-            val otherHand = if (left.isVariableReference(inputVariable)) {
-                right
-            }
-            else if (right.isVariableReference(inputVariable)) {
-                left
-            }
-            else {
-                return null
+            val otherHand = when {
+                left.isVariableReference(inputVariable) -> right
+                right.isVariableReference(inputVariable) -> left
+                else -> return null
             }
 
             val variableInitialization = otherHand.findVariableInitializationBeforeLoop(loop, checkNoOtherUsagesInLoop = false)
@@ -163,14 +155,10 @@ class MaxOrMinTransformation(
 
             if (!assignmentTarget.isVariableReference(variableInitialization.variable)) return null
 
-            val valueToBeVariable = if (valueAssignedIfTrue.isVariableReference(inputVariable)) {
-                valueAssignedIfFalse
-            }
-            else if (valueAssignedIfFalse.isVariableReference(inputVariable)) {
-                valueAssignedIfTrue
-            }
-            else {
-                return null
+            val valueToBeVariable = when {
+                valueAssignedIfTrue.isVariableReference(inputVariable) -> valueAssignedIfFalse
+                valueAssignedIfFalse.isVariableReference(inputVariable) -> valueAssignedIfTrue
+                else -> return null
             }
             if (valueToBeVariable != null && !valueToBeVariable.isVariableReference(variableInitialization.variable)) return null
 

idea/src/org/jetbrains/kotlin/idea/presentation/DeclarationPresenters.kt

@@ -54,14 +54,10 @@ open class KotlinDefaultNamedDeclarationPresentation(private val declaration: Kt
             qualifiedContainer
         }
         val receiverTypeRef = (declaration as? KtCallableDeclaration)?.receiverTypeReference
-        if (receiverTypeRef != null) {
-            return "(for " + receiverTypeRef.text + " in " + containerText + ")"
-        }
-        else if (parent is KtFile) {
-            return "(" + containerText + ")"
-        }
-        else {
-            return "(in " + containerText + ")"
+        return when {
+            receiverTypeRef != null -> "(for " + receiverTypeRef.text + " in " + containerText + ")"
+            parent is KtFile -> "($containerText)"
+            else -> "(in $containerText)"
         }
     }
 

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

@@ -63,15 +63,13 @@ abstract class ChangeFunctionSignatureFix(
         val argumentName = argument.getArgumentName()
         val expression = argument.getArgumentExpression()
 
-        return if (argumentName != null) {
-            KotlinNameSuggester.suggestNameByName(argumentName.asName.asString(), validator)
-        }
-        else if (expression != null) {
-            val bindingContext = expression.analyze(BodyResolveMode.PARTIAL)
-            KotlinNameSuggester.suggestNamesByExpressionAndType(expression, null, bindingContext, validator, "param").first()
-        }
-        else {
-            KotlinNameSuggester.suggestNameByName("param", validator)
+        return when {
+            argumentName != null -> KotlinNameSuggester.suggestNameByName(argumentName.asName.asString(), validator)
+            expression != null -> {
+                val bindingContext = expression.analyze(BodyResolveMode.PARTIAL)
+                KotlinNameSuggester.suggestNamesByExpressionAndType(expression, null, bindingContext, validator, "param").first()
+            }
+            else -> KotlinNameSuggester.suggestNameByName("param", validator)
         }
     }
 

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

@@ -100,16 +100,20 @@ class ReplaceInfixOrOperatorCallFix(
             val parent = expression.parent
             return when (parent) {
                 is KtBinaryExpression -> {
-                    if (parent.left == null || parent.right == null) null
-                    else if (parent.operationToken == KtTokens.EQ) null
-                    else if (parent.operationToken in OperatorConventions.COMPARISON_OPERATIONS) null
-                    else ReplaceInfixOrOperatorCallFix(parent, parent.shouldHaveNotNullType())
+                    when {
+                        parent.left == null || parent.right == null -> null
+                        parent.operationToken == KtTokens.EQ -> null
+                        parent.operationToken in OperatorConventions.COMPARISON_OPERATIONS -> null
+                        else -> ReplaceInfixOrOperatorCallFix(parent, parent.shouldHaveNotNullType())
+                    }
                 }
                 is KtCallExpression -> {
-                    if (parent.calleeExpression == null) null
-                    else if (parent.parent is KtQualifiedExpression) null
-                    else if (parent.getResolvedCall(parent.analyze())?.getImplicitReceiverValue() != null) null
-                    else ReplaceInfixOrOperatorCallFix(parent, parent.shouldHaveNotNullType())
+                    when {
+                        parent.calleeExpression == null -> null
+                        parent.parent is KtQualifiedExpression -> null
+                        parent.getResolvedCall(parent.analyze())?.getImplicitReceiverValue() != null -> null
+                        else -> ReplaceInfixOrOperatorCallFix(parent, parent.shouldHaveNotNullType())
+                    }
                 }
                 else -> null
             }

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

@@ -41,14 +41,10 @@ class SpecifyTypeExplicitlyFix : PsiElementBaseIntentionAction() {
 
     override fun isAvailable(project: Project, editor: Editor, element: PsiElement): Boolean {
         val declaration = declarationByElement(element)
-        if (declaration is KtProperty) {
-            text = "Specify type explicitly"
-        }
-        else if (declaration is KtNamedFunction) {
-            text = "Specify return type explicitly"
-        }
-        else {
-            return false
+        text = when (declaration) {
+            is KtProperty -> "Specify type explicitly"
+            is KtNamedFunction -> "Specify return type explicitly"
+            else -> return false
         }
 
         return !SpecifyTypeExplicitlyIntention.getTypeForDeclaration(declaration).isError

idea/src/org/jetbrains/kotlin/idea/quickfix/migration/MigrateExternalExtensionFix.kt

@@ -96,19 +96,23 @@ class MigrateExternalExtensionFix(declaration: KtNamedDeclaration)
         val nativeAnnotations = ArrayList<KtAnnotationEntry>()
 
         declaration.modifierList?.annotationEntries?.forEach {
-            if (it.isJsAnnotation(PredefinedAnnotation.NATIVE_GETTER)) {
-                isGetter = true
-                nativeAnnotations.add(it)
-            } else if (it.isJsAnnotation(PredefinedAnnotation.NATIVE_SETTER)) {
-                isSetter = true
-                nativeAnnotations.add(it)
-            } else if (it.isJsAnnotation(PredefinedAnnotation.NATIVE_INVOKE)) {
-                isInvoke = true
-                nativeAnnotations.add(it)
-            } else if (it.isJsAnnotation(PredefinedAnnotation.NATIVE)) {
-                nativeAnnotations.add(it)
-                nativeAnnotation = it
-
+            when {
+                it.isJsAnnotation(PredefinedAnnotation.NATIVE_GETTER) -> {
+                    isGetter = true
+                    nativeAnnotations.add(it)
+                }
+                it.isJsAnnotation(PredefinedAnnotation.NATIVE_SETTER) -> {
+                    isSetter = true
+                    nativeAnnotations.add(it)
+                }
+                it.isJsAnnotation(PredefinedAnnotation.NATIVE_INVOKE) -> {
+                    isInvoke = true
+                    nativeAnnotations.add(it)
+                }
+                it.isJsAnnotation(PredefinedAnnotation.NATIVE) -> {
+                    nativeAnnotations.add(it)
+                    nativeAnnotation = it
+                }
             }
         }
         return JsNativeAnnotations(nativeAnnotations, nativeAnnotation, isGetter, isSetter, isInvoke)
@@ -122,30 +126,35 @@ class MigrateExternalExtensionFix(declaration: KtNamedDeclaration)
         val ktPsiFactory = KtPsiFactory(declaration)
         val body = ktPsiFactory.buildExpression {
             appendName(Name.identifier("asDynamic"))
-            if (annotations.isGetter) {
-                appendFixedText("()")
-                if (declaration is KtNamedFunction) {
-                    appendParameters(declaration, "[", "]")
-                }
-            } else if (annotations.isSetter) {
-                appendFixedText("()")
-                if (declaration is KtNamedFunction) {
-                    appendParameters(declaration, "[", "]", skipLast = true)
-                    declaration.valueParameters.last().nameAsName?.let {
-                        appendFixedText(" = ")
-                        appendName(it)
+            when {
+                annotations.isGetter -> {
+                    appendFixedText("()")
+                    if (declaration is KtNamedFunction) {
+                        appendParameters(declaration, "[", "]")
                     }
                 }
-            } else if (annotations.isInvoke) {
-                appendFixedText("()")
-                if (declaration is KtNamedFunction) {
-                    appendParameters(declaration, "(", ")")
+                annotations.isSetter -> {
+                    appendFixedText("()")
+                    if (declaration is KtNamedFunction) {
+                        appendParameters(declaration, "[", "]", skipLast = true)
+                        declaration.valueParameters.last().nameAsName?.let {
+                            appendFixedText(" = ")
+                            appendName(it)
+                        }
+                    }
                 }
-            } else {
-                appendFixedText("().")
-                appendName(name)
-                if (declaration is KtNamedFunction) {
-                    appendParameters(declaration, "(", ")")
+                annotations.isInvoke -> {
+                    appendFixedText("()")
+                    if (declaration is KtNamedFunction) {
+                        appendParameters(declaration, "(", ")")
+                    }
+                }
+                else -> {
+                    appendFixedText("().")
+                    appendName(name)
+                    if (declaration is KtNamedFunction) {
+                        appendParameters(declaration, "(", ")")
+                    }
                 }
             }
         }

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/KotlinChangeSignatureData.kt

@@ -122,33 +122,19 @@ class KotlinChangeSignatureData(
         }
     }
 
-    override fun getParameters(): List<KotlinParameterInfo> {
-        return parameters
+    override fun getParameters(): List<KotlinParameterInfo> = parameters
+
+    override fun getName() = when (baseDescriptor) {
+        is ConstructorDescriptor -> baseDescriptor.containingDeclaration.name.asString()
+        is AnonymousFunctionDescriptor -> ""
+        else -> baseDescriptor.name.asString()
     }
 
-    override fun getName(): String {
-        if (baseDescriptor is ConstructorDescriptor) {
-            return baseDescriptor.containingDeclaration.name.asString()
-        }
-        else if (baseDescriptor is AnonymousFunctionDescriptor) {
-            return ""
-        }
-        else {
-            return baseDescriptor.name.asString()
-        }
-    }
+    override fun getParametersCount(): Int = baseDescriptor.valueParameters.size
 
-    override fun getParametersCount(): Int {
-        return baseDescriptor.valueParameters.size
-    }
+    override fun getVisibility(): Visibility = baseDescriptor.visibility
 
-    override fun getVisibility(): Visibility {
-        return baseDescriptor.visibility
-    }
-
-    override fun getMethod(): PsiElement {
-        return baseDeclaration
-    }
+    override fun getMethod(): PsiElement = baseDeclaration
 
     override fun canChangeVisibility(): Boolean {
         if (DescriptorUtils.isLocal(baseDescriptor)) return false
@@ -156,15 +142,10 @@ class KotlinChangeSignatureData(
         return !(baseDescriptor is AnonymousFunctionDescriptor || parent is ClassDescriptor && parent.kind == ClassKind.INTERFACE)
     }
 
-    override fun canChangeParameters(): Boolean {
-        return true
-    }
+    override fun canChangeParameters() = true
 
-    override fun canChangeName(): Boolean {
-        return !(baseDescriptor is ConstructorDescriptor || baseDescriptor is AnonymousFunctionDescriptor)
-    }
+    override fun canChangeName() = !(baseDescriptor is ConstructorDescriptor || baseDescriptor is AnonymousFunctionDescriptor)
 
-    override fun canChangeReturnType(): MethodDescriptor.ReadWriteOption {
-        return if (baseDescriptor is ConstructorDescriptor) MethodDescriptor.ReadWriteOption.None else MethodDescriptor.ReadWriteOption.ReadWrite
-    }
+    override fun canChangeReturnType(): MethodDescriptor.ReadWriteOption =
+            if (baseDescriptor is ConstructorDescriptor) MethodDescriptor.ReadWriteOption.None else MethodDescriptor.ReadWriteOption.ReadWrite
 }

idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/ui/KotlinChangeSignatureDialog.kt

@@ -248,16 +248,18 @@ class KotlinChangeSignatureDialog(
                 return JBTableRow { column ->
                     val columnInfo = parametersTableModel.columnInfos[column]
 
-                    if (KotlinPrimaryConstructorParameterTableModel.isValVarColumn(columnInfo))
-                        (components[column] as @Suppress("NO_TYPE_ARGUMENTS_ON_RHS") JComboBox).selectedItem
-                    else if (KotlinCallableParameterTableModel.isTypeColumn(columnInfo))
-                        item.typeCodeFragment
-                    else if (KotlinCallableParameterTableModel.isNameColumn(columnInfo))
-                        (components[column] as EditorTextField).text
-                    else if (KotlinCallableParameterTableModel.isDefaultValueColumn(columnInfo))
-                        item.defaultValueCodeFragment
-                    else
-                        null
+                    when {
+                        KotlinPrimaryConstructorParameterTableModel.isValVarColumn(columnInfo) ->
+                            (components[column] as @Suppress("NO_TYPE_ARGUMENTS_ON_RHS") JComboBox).selectedItem
+                        KotlinCallableParameterTableModel.isTypeColumn(columnInfo) ->
+                            item.typeCodeFragment
+                        KotlinCallableParameterTableModel.isNameColumn(columnInfo) ->
+                            (components[column] as EditorTextField).text
+                        KotlinCallableParameterTableModel.isDefaultValueColumn(columnInfo) ->
+                            item.defaultValueCodeFragment
+                        else ->
+                            null
+                    }
                 }
             }
 
@@ -291,9 +293,11 @@ class KotlinChangeSignatureDialog(
 
             override fun getPreferredFocusedComponent(): JComponent {
                 val me = mouseEvent
-                val index = if (me != null)
-                    getEditorIndex(me.point.getX().toInt())
-                else if (myMethod.kind === Kind.PRIMARY_CONSTRUCTOR) 1 else 0
+                val index = when {
+                    me != null -> getEditorIndex(me.point.getX().toInt())
+                    myMethod.kind === Kind.PRIMARY_CONSTRUCTOR -> 1
+                    else -> 0
+                }
                 val component = components[index]
                 return if (component is EditorTextField) component.focusTarget else component
             }

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

@@ -353,16 +353,12 @@ private fun makeCall(
                 )
 
             is Jump -> {
-                if (outputValue.elementToInsertAfterCall == null) {
-                    Collections.singletonList(psiFactory.createExpression(callText))
-                }
-                else if (outputValue.conditional) {
-                    Collections.singletonList(
+                when {
+                    outputValue.elementToInsertAfterCall == null -> Collections.singletonList(psiFactory.createExpression(callText))
+                    outputValue.conditional -> Collections.singletonList(
                             psiFactory.createExpression("if ($callText) ${outputValue.elementToInsertAfterCall.text}")
                     )
-                }
-                else {
-                    listOf(
+                    else -> listOf(
                             psiFactory.createExpression(callText),
                             newLine,
                             psiFactory.createExpression(outputValue.elementToInsertAfterCall.text!!)

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceTypeAlias/introduceTypeAliasImpl.kt

@@ -134,14 +134,13 @@ fun IntroduceTypeAliasDescriptor.validate(): IntroduceTypeAliasDescriptorWithCon
     val conflicts = MultiMap<PsiElement, String>()
 
     val originalType = originalData.originalTypeElement
-    if (name.isEmpty()) {
-        conflicts.putValue(originalType, "No name provided for type alias")
-    }
-    else if (!KotlinNameSuggester.isIdentifier(name)) {
-        conflicts.putValue(originalType, "Type alias name must be a valid identifier: $name")
-    }
-    else if (originalData.getTargetScope().findClassifier(Name.identifier(name), NoLookupLocation.FROM_IDE) != null) {
-        conflicts.putValue(originalType, "Type $name already exists in the target scope")
+    when {
+        name.isEmpty() ->
+            conflicts.putValue(originalType, "No name provided for type alias")
+        !KotlinNameSuggester.isIdentifier(name) ->
+            conflicts.putValue(originalType, "Type alias name must be a valid identifier: $name")
+        originalData.getTargetScope().findClassifier(Name.identifier(name), NoLookupLocation.FROM_IDE) != null ->
+            conflicts.putValue(originalType, "Type $name already exists in the target scope")
     }
 
     if (typeParameters.distinctBy { it.name }.size != typeParameters.size) {

idea/src/org/jetbrains/kotlin/idea/run/KotlinRunConfigurationProducer.kt

@@ -97,12 +97,14 @@ class KotlinRunConfigurationProducer : RunConfigurationProducer<JetRunConfigurat
             null -> null
             is KtFile -> container.javaFileFacadeFqName.asString()
             is KtClassOrObject -> {
-                if (!container.isValid)
+                if (!container.isValid) {
                     null
+                }
                 else if (container is KtObjectDeclaration && container.isCompanion()) {
                     val containerClass = container.getParentOfType<KtClass>(true)
                     containerClass?.toLightClass()?.let { ClassUtil.getJVMClassName(it) }
-                } else {
+                }
+                else {
                     container.toLightClass()?.let { ClassUtil.getJVMClassName(it) }
                 }
             }

idea/src/org/jetbrains/kotlin/idea/versions/OutdatedKotlinRuntimeChecker.kt

@@ -115,17 +115,19 @@ fun notifyOutdatedKotlinRuntime(project: Project, outdatedLibraries: Collection<
     Notifications.Bus.notify(Notification(OUTDATED_RUNTIME_GROUP_DISPLAY_ID, "Outdated Kotlin Runtime", message,
                                           NotificationType.WARNING, NotificationListener { notification, event ->
         if (event.eventType == HyperlinkEvent.EventType.ACTIVATED) {
-            if ("update" == event.description) {
-                val outdatedLibraries = findOutdatedKotlinLibraries(project).map { it.library }
-                ApplicationManager.getApplication().invokeLater {
-                    updateLibraries(project, outdatedLibraries)
+            when {
+                "update" == event.description -> {
+                    val outdatedLibraries = findOutdatedKotlinLibraries(project).map { it.library }
+                    ApplicationManager.getApplication().invokeLater {
+                        updateLibraries(project, outdatedLibraries)
+                    }
+                }
+                "ignore" == event.description -> {
+                    PropertiesComponent.getInstance(project).setValue(SUPPRESSED_PROPERTY_NAME, pluginVersion)
+                }
+                else -> {
+                    throw AssertionError()
                 }
-            }
-            else if ("ignore" == event.description) {
-                PropertiesComponent.getInstance(project).setValue(SUPPRESSED_PROPERTY_NAME, pluginVersion)
-            }
-            else {
-                throw AssertionError()
             }
             notification.expire()
         }

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

@@ -345,44 +345,44 @@ class DefaultExpressionConverter : JavaElementVisitor(), ExpressionConverter {
         if (target is KtLightMethod) {
             val origin = target.kotlinOrigin
             val isTopLevel = origin?.getStrictParentOfType<KtClassOrObject>() == null
-            if (origin is KtProperty || origin is KtPropertyAccessor || origin is KtParameter) {
-                val property = if (origin is KtPropertyAccessor)
-                    origin.parent as KtProperty
-                else
-                    origin as KtNamedDeclaration
-                val parameterCount = target.parameterList.parameters.size
-                if (parameterCount == arguments.size) {
-                    val propertyName = Identifier.withNoPrototype(property.name!!, isNullable)
-                    val isExtension = property.isExtensionDeclaration()
-                    val propertyAccess = if (isTopLevel) {
-                        if (isExtension)
-                            QualifiedExpression(codeConverter.convertExpression(arguments.firstOrNull(), shouldParenthesize = true), propertyName, null).assignNoPrototype()
-                        else
+            when (origin) {
+                is KtProperty, is KtPropertyAccessor, is KtParameter -> {
+                    val property = if (origin is KtPropertyAccessor)
+                        origin.parent as KtProperty
+                    else
+                        origin as KtNamedDeclaration
+                    val parameterCount = target.parameterList.parameters.size
+                    if (parameterCount == arguments.size) {
+                        val propertyName = Identifier.withNoPrototype(property.name!!, isNullable)
+                        val isExtension = property.isExtensionDeclaration()
+                        val propertyAccess = if (isTopLevel) {
+                            if (isExtension)
+                                QualifiedExpression(codeConverter.convertExpression(arguments.firstOrNull(), shouldParenthesize = true), propertyName, null).assignNoPrototype()
+                            else
+                                propertyName
+                        }
+                        else if (qualifier != null) {
+                            QualifiedExpression(codeConverter.convertExpression(qualifier), propertyName, dot).assignNoPrototype()
+                        }
+                        else {
                             propertyName
-                    }
-                    else if (qualifier != null) {
-                        QualifiedExpression(codeConverter.convertExpression(qualifier), propertyName, dot).assignNoPrototype()
-                    }
-                    else {
-                        propertyName
-                    }
-
-                    when(if (isExtension) parameterCount - 1 else parameterCount) {
-                        0 /* getter */ -> {
-                            result = propertyAccess
-                            return
                         }
 
-                        1 /* setter */ -> {
-                            val argument = codeConverter.convertExpression(arguments[if (isExtension) 1 else 0])
-                            result = AssignmentExpression(propertyAccess, argument, Operator.EQ)
-                            return
+                        when(if (isExtension) parameterCount - 1 else parameterCount) {
+                            0 /* getter */ -> {
+                                result = propertyAccess
+                                return
+                            }
+
+                            1 /* setter */ -> {
+                                val argument = codeConverter.convertExpression(arguments[if (isExtension) 1 else 0])
+                                result = AssignmentExpression(propertyAccess, argument, Operator.EQ)
+                                return
+                            }
                         }
                     }
                 }
-            }
-            else if (origin is KtFunction) {
-                if (isTopLevel) {
+                is KtFunction -> if (isTopLevel) {
                     result = if (origin.isExtensionDeclaration()) {
                         val qualifier = codeConverter.convertExpression(arguments.firstOrNull(), shouldParenthesize = true)
                         MethodCallExpression.build(qualifier,
@@ -401,27 +401,27 @@ class DefaultExpressionConverter : JavaElementVisitor(), ExpressionConverter {
                     }
                     return
                 }
-            }
-            else if (origin == null){
-                val resolvedQualifier = (methodExpr.qualifier as? PsiReferenceExpression)?.resolve()
-                if (isFacadeClassFromLibrary(resolvedQualifier)) {
-                    result = if (target.isKotlinExtensionFunction()) {
-                        val qualifier = codeConverter.convertExpression(arguments.firstOrNull(), shouldParenthesize = true)
-                        MethodCallExpression.build(qualifier,
-                                                   methodExpr.referenceName!!,
-                                                   convertArguments(expression, isExtension = true),
-                                                   typeArguments,
-                                                   isNullable,
-                                                   dot)
+                null -> {
+                    val resolvedQualifier = (methodExpr.qualifier as? PsiReferenceExpression)?.resolve()
+                    if (isFacadeClassFromLibrary(resolvedQualifier)) {
+                        result = if (target.isKotlinExtensionFunction()) {
+                            val qualifier = codeConverter.convertExpression(arguments.firstOrNull(), shouldParenthesize = true)
+                            MethodCallExpression.build(qualifier,
+                                                       methodExpr.referenceName!!,
+                                                       convertArguments(expression, isExtension = true),
+                                                       typeArguments,
+                                                       isNullable,
+                                                       dot)
+                        }
+                        else {
+                            MethodCallExpression.build(null,
+                                                       methodExpr.referenceName!!,
+                                                       convertArguments(expression),
+                                                       typeArguments,
+                                                       isNullable)
+                        }
+                        return
                     }
-                    else {
-                        MethodCallExpression.build(null,
-                                                   methodExpr.referenceName!!,
-                                                   convertArguments(expression),
-                                                   typeArguments,
-                                                   isNullable)
-                    }
-                    return
                 }
             }
         }
@@ -826,39 +826,40 @@ class DefaultExpressionConverter : JavaElementVisitor(), ExpressionConverter {
 
         val specialMethod = method?.let { SpecialMethod.match(it, callParams.size, converter.services) }
         val statement: Statement
-        if (expression.isConstructor) {
-            val argumentList = ArgumentList.withNoPrototype(callParams.map { it.first })
-            statement = MethodCallExpression.buildNonNull(null, convertMethodReferenceQualifier(qualifier), argumentList)
-        }
-        else if (specialMethod != null) {
-            val factory = PsiElementFactory.SERVICE.getInstance(converter.project)
-            val fakeReceiver = receiver?.let {
-                val psiExpression = qualifier as? PsiExpression ?: factory.createExpressionFromText("fakeReceiver", null)
-                psiExpression.convertedExpression = it.first
-                psiExpression
+        when {
+            expression.isConstructor -> {
+                val argumentList = ArgumentList.withNoPrototype(callParams.map { it.first })
+                statement = MethodCallExpression.buildNonNull(null, convertMethodReferenceQualifier(qualifier), argumentList)
             }
-            val fakeParams = callParams.mapIndexed {
-                i, param ->
-                with(factory.createExpressionFromText("fake$i", null)) {
-                    this.convertedExpression = param.first
-                    this
+            specialMethod != null -> {
+                val factory = PsiElementFactory.SERVICE.getInstance(converter.project)
+                val fakeReceiver = receiver?.let {
+                    val psiExpression = qualifier as? PsiExpression ?: factory.createExpressionFromText("fakeReceiver", null)
+                    psiExpression.convertedExpression = it.first
+                    psiExpression
                 }
-            }
-            val patchedConverter = codeConverter.withSpecialExpressionConverter(object : SpecialExpressionConverter {
-                override fun convertExpression(expression: PsiExpression, codeConverter: CodeConverter): Expression? {
-                    val convertedExpression = expression.convertedExpression
-                    expression.convertedExpression = null
-                    return convertedExpression
+                val fakeParams = callParams.mapIndexed { i, param ->
+                    with(factory.createExpressionFromText("fake$i", null)) {
+                        this.convertedExpression = param.first
+                        this
+                    }
                 }
-            })
+                val patchedConverter = codeConverter.withSpecialExpressionConverter(object : SpecialExpressionConverter {
+                    override fun convertExpression(expression: PsiExpression, codeConverter: CodeConverter): Expression? {
+                        val convertedExpression = expression.convertedExpression
+                        expression.convertedExpression = null
+                        return convertedExpression
+                    }
+                })
 
-            val callData = SpecialMethod.ConvertCallData(fakeReceiver, fakeParams, emptyList(), null, null, null, patchedConverter)
-            statement = specialMethod.convertCall(callData)!!
-        }
-        else {
-            val referenceName = expression.referenceName!!
-            val argumentList = ArgumentList.withNoPrototype(callParams.map { it.first })
-            statement = MethodCallExpression.buildNonNull(receiver?.first, referenceName, argumentList)
+                val callData = SpecialMethod.ConvertCallData(fakeReceiver, fakeParams, emptyList(), null, null, null, patchedConverter)
+                statement = specialMethod.convertCall(callData)!!
+            }
+            else -> {
+                val referenceName = expression.referenceName!!
+                val argumentList = ArgumentList.withNoPrototype(callParams.map { it.first })
+                statement = MethodCallExpression.buildNonNull(receiver?.first, referenceName, argumentList)
+            }
         }
 
         statement.assignNoPrototype()

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

@@ -104,13 +104,14 @@ class ForConverter(
                 statement.isInSingleLine()).assignNoPrototype()
         if (initializationConverted.isEmpty) return whileStatement
 
-        val kind = if (statement.parents.filter { it !is PsiLabeledStatement }.first() !is PsiCodeBlock) {
-            WhileWithInitializationPseudoStatement.Kind.WITH_BLOCK
+        val kind = when {
+            statement.parents.filter { it !is PsiLabeledStatement }.first() !is PsiCodeBlock ->
+                WhileWithInitializationPseudoStatement.Kind.WITH_BLOCK
+            hasNameConflict() ->
+                WhileWithInitializationPseudoStatement.Kind.WITH_RUN_BLOCK
+            else ->
+                WhileWithInitializationPseudoStatement.Kind.SIMPLE
         }
-        else if (hasNameConflict())
-            WhileWithInitializationPseudoStatement.Kind.WITH_RUN_BLOCK
-        else
-            WhileWithInitializationPseudoStatement.Kind.SIMPLE
         return WhileWithInitializationPseudoStatement(initializationConverted, whileStatement, kind)
     }
 

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

@@ -266,12 +266,14 @@ class TypeConverter(val converter: Converter) {
 
         override fun fromAnnotations(owner: PsiModifierListOwner): Nullability {
             val manager = NullableNotNullManager.getInstance(owner.project)
-            return if (manager.isNotNull(owner, false/* we do not check bases because they are checked by callers of this method*/))
-                Nullability.NotNull
-            else if (manager.isNullable(owner, false))
-                Nullability.Nullable
-            else
-                Nullability.Default
+            return when {
+                manager.isNotNull(owner, false/* we do not check bases because they are checked by callers of this method*/) ->
+                    Nullability.NotNull
+                manager.isNullable(owner, false) ->
+                    Nullability.Nullable
+                else ->
+                    Nullability.Default
+            }
         }
 
         override fun forVariableTypeBeforeUsageSearch(variable: PsiVariable): Nullability {

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

@@ -40,17 +40,11 @@ class TypeVisitor(
 
     override fun visitPrimitiveType(primitiveType: PsiPrimitiveType): Type {
         val name = primitiveType.canonicalText
-        return if (name == "void") {
-            UnitType()
-        }
-        else if (PRIMITIVE_TYPES_NAMES.contains(name)) {
-            PrimitiveType(Identifier.withNoPrototype(StringUtil.capitalize(name)))
-        }
-        else if (name == "null") {
-            NullType()
-        }
-        else {
-            PrimitiveType(Identifier.withNoPrototype(name))
+        return when {
+            name == "void" -> UnitType()
+            PRIMITIVE_TYPES_NAMES.contains(name) -> PrimitiveType(Identifier.withNoPrototype(StringUtil.capitalize(name)))
+            name == "null" -> NullType()
+            else -> PrimitiveType(Identifier.withNoPrototype(name))
         }
     }
 

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

@@ -27,20 +27,16 @@ fun quoteKeywords(packageName: String): String = packageName.split('.').joinToSt
 
 fun getDefaultInitializer(property: Property): Expression? {
     val t = property.type
-    val result = if (t.isNullable) {
-        LiteralExpression("null")
-    }
-    else if (t is PrimitiveType) {
-        when (t.name.name) {
+    val result = when {
+        t.isNullable -> LiteralExpression("null")
+        t is PrimitiveType -> when (t.name.name) {
             "Boolean" -> LiteralExpression("false")
             "Char" -> LiteralExpression("' '")
             "Double" -> MethodCallExpression.buildNonNull(LiteralExpression("0").assignNoPrototype(), OperatorConventions.DOUBLE.toString())
             "Float" -> MethodCallExpression.buildNonNull(LiteralExpression("0").assignNoPrototype(), OperatorConventions.FLOAT.toString())
             else -> LiteralExpression("0")
         }
-    }
-    else {
-        null
+        else -> null
     }
     return result?.assignNoPrototype()
 }

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

@@ -279,11 +279,10 @@ class ClassLiteralExpression(val type: Type): Expression() {
 
 fun createArrayInitializerExpression(arrayType: ArrayType, initializers: List<Expression>, needExplicitType: Boolean = true) : MethodCallExpression {
     val elementType = arrayType.elementType
-    val createArrayFunction = if (elementType is PrimitiveType)
-            (elementType.toNotNullType().canonicalCode() + "ArrayOf").decapitalize()
-        else if (needExplicitType)
-            "arrayOf<" + arrayType.elementType.canonicalCode() + ">"
-        else
-            "arrayOf"
+    val createArrayFunction = when {
+        elementType is PrimitiveType -> (elementType.toNotNullType().canonicalCode() + "ArrayOf").decapitalize()
+        needExplicitType -> "arrayOf<" + arrayType.elementType.canonicalCode() + ">"
+        else -> "arrayOf"
+    }
     return MethodCallExpression.buildNonNull(null, createArrayFunction, ArgumentList.withNoPrototype(initializers))
 }

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

@@ -387,14 +387,10 @@ private class PropertyDetector(
             modifiers.add(Modifier.OVERRIDE)
         }
 
-        if (getMethod != null) {
-            modifiers.addIfNotNull(getterModifiers.accessModifier())
-        }
-        else if (setMethod != null) {
-            modifiers.addIfNotNull(getterModifiers.accessModifier())
-        }
-        else {
-            modifiers.addIfNotNull(fieldModifiers.accessModifier())
+        when {
+            getMethod != null -> modifiers.addIfNotNull(getterModifiers.accessModifier())
+            setMethod != null -> modifiers.addIfNotNull(getterModifiers.accessModifier())
+            else -> modifiers.addIfNotNull(fieldModifiers.accessModifier())
         }
 
         val prototypes = listOfNotNull<PsiElement>(field, getMethod, setMethod)
@@ -432,16 +428,20 @@ private class PropertyDetector(
         val superMethod = converter.services.superMethodsSearcher.findDeepestSuperMethods(getOrSetMethod).firstOrNull() ?: return null
 
         val containingClass = superMethod.containingClass!!
-        if (converter.inConversionScope(containingClass)) {
-            val propertyInfo = converter.propertyDetectionCache[containingClass][superMethod]
-            return if (propertyInfo != null) SuperInfo.Property(propertyInfo.isVar, propertyInfo.name, propertyInfo.modifiers.contains(Modifier.ABSTRACT)) else SuperInfo.Function
-        }
-        else if (superMethod is KtLightMethod) {
-            val origin = superMethod.kotlinOrigin
-            return if (origin is KtProperty) SuperInfo.Property(origin.isVar, origin.name ?: "", origin.hasModifier(KtTokens.ABSTRACT_KEYWORD)) else SuperInfo.Function
-        }
-        else {
-            return SuperInfo.Function
+        return when {
+            converter.inConversionScope(containingClass) -> {
+                val propertyInfo = converter.propertyDetectionCache[containingClass][superMethod]
+                if (propertyInfo != null) SuperInfo.Property(propertyInfo.isVar, propertyInfo.name, propertyInfo.modifiers.contains(Modifier.ABSTRACT))
+                else SuperInfo.Function
+            }
+            superMethod is KtLightMethod -> {
+                val origin = superMethod.kotlinOrigin
+                if (origin is KtProperty) SuperInfo.Property(origin.isVar, origin.name ?: "", origin.hasModifier(KtTokens.ABSTRACT_KEYWORD))
+                else SuperInfo.Function
+            }
+            else -> {
+                SuperInfo.Function
+            }
         }
     }
 

j2k/src/org/jetbrains/kotlin/j2k/usageProcessing/FieldToPropertyProcessing.kt

@@ -37,12 +37,11 @@ class FieldToPropertyProcessing(
             if (field.name != propertyName || replaceReadWithFieldReference || replaceWriteWithFieldReference) MyConvertedCodeProcessor() else null
 
     override var javaCodeProcessors =
-            if (field.hasModifierProperty(PsiModifier.PRIVATE))
-                emptyList()
-            else if (field.name != propertyName)
-                listOf(ElementRenamedCodeProcessor(propertyName), UseAccessorsJavaCodeProcessor())
-            else
-                listOf(UseAccessorsJavaCodeProcessor())
+            when {
+                field.hasModifierProperty(PsiModifier.PRIVATE) -> emptyList()
+                field.name != propertyName -> listOf(ElementRenamedCodeProcessor(propertyName), UseAccessorsJavaCodeProcessor())
+                else -> listOf(UseAccessorsJavaCodeProcessor())
+            }
 
     override val kotlinCodeProcessors =
             if (field.name != propertyName)

js/js.dce/src/org/jetbrains/kotlin/js/dce/Analyzer.kt

@@ -56,54 +56,50 @@ class Analyzer(private val context: Context) : JsVisitor() {
 
     override fun visitExpressionStatement(x: JsExpressionStatement) {
         val expression = x.expression
-        if (expression is JsBinaryOperation) {
-            if (expression.operator == JsBinaryOperator.ASG) {
+        when (expression) {
+            is JsBinaryOperation -> if (expression.operator == JsBinaryOperator.ASG) {
                 processAssignment(x, expression.arg1, expression.arg2)?.let {
                     // Mark this statement with FQN extracted from assignment.
                     // Later, we eliminate such statements if corresponding FQN is reachable
                     nodeMap[x] = it
                 }
             }
-        }
-        else if (expression is JsFunction) {
-            expression.name?.let { context.nodes[it]?.original }?.let {
+            is JsFunction -> expression.name?.let { context.nodes[it]?.original }?.let {
                 nodeMap[x] = it
                 it.functions += expression
             }
-        }
-        else if (expression is JsInvocation) {
-            val function = expression.qualifier
+            is JsInvocation -> {
+                val function = expression.qualifier
 
-            // (function(params) { ... })(arguments), assume that params = arguments and walk its body
-            if (function is JsFunction) {
-                enterFunction(function, expression.arguments)
-                return
-            }
-
-            // f(arguments), where f is a parameter of outer function and it always receives function() { } as an argument.
-            if (function is JsNameRef && function.qualifier == null) {
-                val postponedFunction = function.name?.let { postponedFunctions[it] }
-                if (postponedFunction != null) {
-                    enterFunction(postponedFunction, expression.arguments)
-                    invocationsToSkip += expression
+                // (function(params) { ... })(arguments), assume that params = arguments and walk its body
+                if (function is JsFunction) {
+                    enterFunction(function, expression.arguments)
                     return
                 }
-            }
 
-            // Object.defineProperty()
-            if (context.isObjectDefineProperty(function)) {
-                handleObjectDefineProperty(x, expression.arguments.getOrNull(0), expression.arguments.getOrNull(1),
-                                           expression.arguments.getOrNull(2))
-            }
+                // f(arguments), where f is a parameter of outer function and it always receives function() { } as an argument.
+                if (function is JsNameRef && function.qualifier == null) {
+                    val postponedFunction = function.name?.let { postponedFunctions[it] }
+                    if (postponedFunction != null) {
+                        enterFunction(postponedFunction, expression.arguments)
+                        invocationsToSkip += expression
+                        return
+                    }
+                }
 
-            // Kotlin.defineModule()
-            else if (context.isDefineModule(function)) {
-                // (just remove it)
-                astNodesToEliminate += x
-            }
+                // Object.defineProperty()
+                when {
+                    context.isObjectDefineProperty(function) ->
+                        handleObjectDefineProperty(x, expression.arguments.getOrNull(0), expression.arguments.getOrNull(1),
+                                                   expression.arguments.getOrNull(2))
 
-            else if (context.isAmdDefine(function)) {
-                handleAmdDefine(expression, expression.arguments)
+                // Kotlin.defineModule()
+                    context.isDefineModule(function) ->
+                        // (just remove it)
+                        astNodesToEliminate += x
+                    context.isAmdDefine(function) ->
+                        handleAmdDefine(expression, expression.arguments)
+                }
             }
         }
     }
@@ -201,77 +197,75 @@ class Analyzer(private val context: Context) : JsVisitor() {
         }
         else if (leftNode != null) {
             // lhs = foo()
-            if (rhs is JsInvocation) {
-                val function = rhs.qualifier
+            when {
+                rhs is JsInvocation -> {
+                    val function = rhs.qualifier
 
-                // lhs = function(params) { ... }(arguments)
-                // see corresponding case in visitExpressionStatement
-                if (function is JsFunction) {
-                    enterFunction(function, rhs.arguments)
-                    astNodesToSkip += lhs
-                    return null
-                }
-
-                // lhs = foo(arguments), where foo is a parameter of outer function that always take function literal
-                // see corresponding case in visitExpressionStatement
-                if (function is JsNameRef && function.qualifier == null) {
-                    function.name?.let { postponedFunctions[it] }?.let {
-                        enterFunction(it, rhs.arguments)
+                    // lhs = function(params) { ... }(arguments)
+                    // see corresponding case in visitExpressionStatement
+                    if (function is JsFunction) {
+                        enterFunction(function, rhs.arguments)
                         astNodesToSkip += lhs
                         return null
                     }
-                }
 
-                // lhs = Object.create(constructor)
-                if (context.isObjectFunction(function, "create")) {
-                    // Do not alias lhs and constructor, make unidirectional dependency lhs -> constructor instead.
-                    // Motivation: reachability of a base class does not imply reachability of its derived class
-                    handleObjectCreate(leftNode, rhs.arguments.getOrNull(0))
-                    return leftNode
-                }
-
-                // lhs = Kotlin.defineInlineFunction('fqn', function() { ... })
-                if (context.isDefineInlineFunction(function) && rhs.arguments.size == 2) {
-                    leftNode.functions += rhs.arguments[1] as JsFunction
-                    val defineInlineFunctionNode = context.extractNode(function)
-                    if (defineInlineFunctionNode != null) {
-                        leftNode.dependencies += defineInlineFunctionNode
-                    }
-                    return leftNode
-                }
-            }
-            else if (rhs is JsBinaryOperation) {
-                // Detect lhs = parent.child || (parent.child = {}), which is used to declare packages.
-                // Assume lhs = parent.child
-                if (rhs.operator == JsBinaryOperator.OR) {
-                    val secondNode = context.extractNode(rhs.arg1)
-                    val reassignment = rhs.arg2
-                    if (reassignment is JsBinaryOperation && reassignment.operator == JsBinaryOperator.ASG) {
-                        val reassignNode = context.extractNode(reassignment.arg1)
-                        val reassignValue = reassignment.arg2
-                        if (reassignNode == secondNode && reassignNode != null && reassignValue is JsObjectLiteral &&
-                            reassignValue.propertyInitializers.isEmpty()
-                        ) {
-                            return processAssignment(node, lhs, rhs.arg1)
+                    // lhs = foo(arguments), where foo is a parameter of outer function that always take function literal
+                    // see corresponding case in visitExpressionStatement
+                    if (function is JsNameRef && function.qualifier == null) {
+                        function.name?.let { postponedFunctions[it] }?.let {
+                            enterFunction(it, rhs.arguments)
+                            astNodesToSkip += lhs
+                            return null
                         }
                     }
+
+                    // lhs = Object.create(constructor)
+                    if (context.isObjectFunction(function, "create")) {
+                        // Do not alias lhs and constructor, make unidirectional dependency lhs -> constructor instead.
+                        // Motivation: reachability of a base class does not imply reachability of its derived class
+                        handleObjectCreate(leftNode, rhs.arguments.getOrNull(0))
+                        return leftNode
+                    }
+
+                    // lhs = Kotlin.defineInlineFunction('fqn', function() { ... })
+                    if (context.isDefineInlineFunction(function) && rhs.arguments.size == 2) {
+                        leftNode.functions += rhs.arguments[1] as JsFunction
+                        val defineInlineFunctionNode = context.extractNode(function)
+                        if (defineInlineFunctionNode != null) {
+                            leftNode.dependencies += defineInlineFunctionNode
+                        }
+                        return leftNode
+                    }
                 }
-            }
-            else if (rhs is JsFunction) {
-                // lhs = function() { ... }
-                // During reachability tracking phase: eliminate it if lhs is unreachable, traverse function otherwise
-                leftNode.functions += rhs
-                return leftNode
-            }
-            else if (leftNode.qualifier?.memberName == Namer.METADATA) {
-                // lhs.$metadata$ = expression
-                // During reachability tracking phase: eliminate it if lhs is unreachable, traverse expression
-                // It's commonly used to supply class's metadata
-                leftNode.expressions += rhs
-                return leftNode
-            }
-            else if (rhs is JsObjectLiteral && rhs.propertyInitializers.isEmpty()) {
-                return leftNode
+                rhs is JsBinaryOperation -> // Detect lhs = parent.child || (parent.child = {}), which is used to declare packages.
+                    // Assume lhs = parent.child
+                    if (rhs.operator == JsBinaryOperator.OR) {
+                        val secondNode = context.extractNode(rhs.arg1)
+                        val reassignment = rhs.arg2
+                        if (reassignment is JsBinaryOperation && reassignment.operator == JsBinaryOperator.ASG) {
+                            val reassignNode = context.extractNode(reassignment.arg1)
+                            val reassignValue = reassignment.arg2
+                            if (reassignNode == secondNode && reassignNode != null && reassignValue is JsObjectLiteral &&
+                                reassignValue.propertyInitializers.isEmpty()
+                                    ) {
+                                return processAssignment(node, lhs, rhs.arg1)
+                            }
+                        }
+                    }
+                rhs is JsFunction -> {
+                    // lhs = function() { ... }
+                    // During reachability tracking phase: eliminate it if lhs is unreachable, traverse function otherwise
+                    leftNode.functions += rhs
+                    return leftNode
+                }
+                leftNode.qualifier?.memberName == Namer.METADATA -> {
+                    // lhs.$metadata$ = expression
+                    // During reachability tracking phase: eliminate it if lhs is unreachable, traverse expression
+                    // It's commonly used to supply class's metadata
+                    leftNode.expressions += rhs
+                    return leftNode
+                }
+                rhs is JsObjectLiteral && rhs.propertyInitializers.isEmpty() -> return leftNode
             }
 
             val nodeInitializedByEmptyObject = extractVariableInitializedByEmptyObject(rhs)

js/js.frontend/src/org/jetbrains/kotlin/js/resolve/diagnostics/JsExternalChecker.kt

@@ -222,15 +222,13 @@ object JsExternalChecker : SimpleDeclarationChecker {
     private fun KtDeclarationWithBody.hasValidExternalBody(bindingContext: BindingContext): Boolean {
         if (!hasBody()) return true
         val body = bodyExpression!!
-        return if (!hasBlockBody()) {
-            body.isDefinedExternallyExpression(bindingContext)
-        }
-        else if (body is KtBlockExpression) {
-            val statement = body.statements.singleOrNull() ?: return false
-            statement.isDefinedExternallyExpression(bindingContext)
-        }
-        else {
-            false
+        return when {
+            !hasBlockBody() -> body.isDefinedExternallyExpression(bindingContext)
+            body is KtBlockExpression -> {
+                val statement = body.statements.singleOrNull() ?: return false
+                statement.isDefinedExternallyExpression(bindingContext)
+            }
+            else -> false
         }
     }
 

js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/RedundantStatementElimination.kt

@@ -66,15 +66,17 @@ class RedundantStatementElimination(private val root: JsFunction) {
     private fun replace(expression: JsExpression): List<JsExpression> {
         return when (expression) {
             is JsNameRef -> {
-                if (expression.name in localVars) {
-                    listOf()
-                }
-                else if (expression.sideEffects != SideEffectKind.AFFECTS_STATE) {
-                    val qualifier = expression.qualifier
-                    if (qualifier != null) replace(qualifier) else listOf()
-                }
-                else {
-                    listOf(expression)
+                when {
+                    expression.name in localVars -> {
+                        listOf()
+                    }
+                    expression.sideEffects != SideEffectKind.AFFECTS_STATE -> {
+                        val qualifier = expression.qualifier
+                        if (qualifier != null) replace(qualifier) else listOf()
+                    }
+                    else -> {
+                        listOf(expression)
+                    }
                 }
             }
 

plugins/annotation-processing/src/org/jetbrains/kotlin/annotation/processing/impl/KotlinElements.kt

@@ -190,35 +190,27 @@ object Constants {
     private fun formatChar(c: Char) = '\'' + quote(c) + '\''
     private fun formatString(s: String) = '"' + quote(s) + '"'
     
-    private fun formatFloat(f: Float): String {
-        if (java.lang.Float.isNaN(f))
-            return "0.0f/0.0f"
-        else if (java.lang.Float.isInfinite(f))
-            return if (f < 0) "-1.0f/0.0f" else "1.0f/0.0f"
-        else
-            return "${f}f"
+    private fun formatFloat(f: Float): String = when {
+        java.lang.Float.isNaN(f) -> "0.0f/0.0f"
+        java.lang.Float.isInfinite(f) -> if (f < 0) "-1.0f/0.0f" else "1.0f/0.0f"
+        else -> "${f}f"
     }
 
-    private fun formatDouble(d: Double): String {
-        if (java.lang.Double.isNaN(d))
-            return "0.0/0.0"
-        else if (java.lang.Double.isInfinite(d))
-            return if (d < 0) "-1.0/0.0" else "1.0/0.0"
-        else
-            return d.toString()
+    private fun formatDouble(d: Double): String = when {
+        java.lang.Double.isNaN(d) -> "0.0/0.0"
+        java.lang.Double.isInfinite(d) -> if (d < 0) "-1.0/0.0" else "1.0/0.0"
+        else -> d.toString()
     }
 
-    fun quote(ch: Char): String {
-        return when (ch) {
-            '\b' -> "\\b"
-            '\n' -> "\\n"
-            '\r' -> "\\r"
-            '\t' -> "\\t"
-            '\'' -> "\\'"
-            '\"' -> "\\\""
-            '\\' -> "\\\\"
-            else -> if (isPrintableAscii(ch)) ch.toString() else String.format("\\u%04x", ch.toInt())
-        }
+    fun quote(ch: Char): String = when (ch) {
+        '\b' -> "\\b"
+        '\n' -> "\\n"
+        '\r' -> "\\r"
+        '\t' -> "\\t"
+        '\'' -> "\\'"
+        '\"' -> "\\\""
+        '\\' -> "\\\\"
+        else -> if (isPrintableAscii(ch)) ch.toString() else String.format("\\u%04x", ch.toInt())
     }
 
     fun quote(s: String): String {

plugins/annotation-processing/src/org/jetbrains/kotlin/annotation/processing/impl/KotlinTypes.kt

@@ -95,12 +95,10 @@ class KotlinTypes(
         if (extendsBound != null && extendsBound !is JePsiType) illegalArg("extendsBound should have PsiType")
         if (superBound != null && superBound !is JePsiType) illegalArg("superBound should have PsiType")
         
-        return JeWildcardType(if (extendsBound != null) {
-            PsiWildcardType.createExtends(psiManager(), (extendsBound as JePsiType).psiType)
-        } else if (superBound != null) {
-            PsiWildcardType.createSuper(psiManager(), (superBound as JePsiType).psiType)
-        } else {
-            PsiWildcardType.createUnbounded(psiManager())
+        return JeWildcardType(when {
+            extendsBound != null -> PsiWildcardType.createExtends(psiManager(), (extendsBound as JePsiType).psiType)
+            superBound != null -> PsiWildcardType.createSuper(psiManager(), (superBound as JePsiType).psiType)
+            else -> PsiWildcardType.createUnbounded(psiManager())
         }, isRaw = false)
     }
 

plugins/lint/lint-idea/src/org/jetbrains/android/inspections/klint/SuppressLintIntentionAction.kt

@@ -80,16 +80,13 @@ class SuppressLintIntentionAction(val id: String, val element: PsiElement) : Int
         val args = entry.valueArgumentList
         val psiFactory = KtPsiFactory(entry)
         val newArgList = psiFactory.createCallArguments("($argument)")
-        if (args == null) {
-            // new argument list
-            entry.addAfter(newArgList, entry.lastChild)
-        }
-        else if (args.arguments.isEmpty()) {
-            // replace '()' with a new argument list
-            args.replace(newArgList)
-        }
-        else if (args.arguments.none { it.textMatches(argument) }) {
-            args.addArgument(newArgList.arguments[0])
+        when {
+            args == null -> // new argument list
+                entry.addAfter(newArgList, entry.lastChild)
+            args.arguments.isEmpty() -> // replace '()' with a new argument list
+                args.replace(newArgList)
+            args.arguments.none { it.textMatches(argument) } ->
+                args.addArgument(newArgList.arguments[0])
         }
 
         return true

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

@@ -286,15 +286,16 @@ internal object KotlinConverter {
             is KtVariableDeclaration -> expr<UDeclarationsExpression>(build(::convertVariablesDeclaration))
 
             is KtStringTemplateExpression -> {
-                if (expression.entries.isEmpty()) {
-                    val parent = if (parentCallback == null) null else (parentCallback() ?: return null)
-                    expr<ULiteralExpression> { KotlinStringULiteralExpression(expression, parent, "") }
-                }
-                else if (expression.entries.size == 1)
-                    convertEntry(expression.entries[0], parentCallback, requiredType)
-                else {
-                    val parent = if (parentCallback == null) null else (parentCallback() ?: return null)
-                    expr<UExpression> { KotlinStringTemplateUPolyadicExpression(expression, parent) }
+                when {
+                    expression.entries.isEmpty() -> {
+                        val parent = if (parentCallback == null) null else (parentCallback() ?: return null)
+                        expr<ULiteralExpression> { KotlinStringULiteralExpression(expression, parent, "") }
+                    }
+                    expression.entries.size == 1 -> convertEntry(expression.entries[0], parentCallback, requiredType)
+                    else -> {
+                        val parent = if (parentCallback == null) null else (parentCallback() ?: return null)
+                        expr<UExpression> { KotlinStringTemplateUPolyadicExpression(expression, parent) }
+                    }
                 }
             }
             is KtDestructuringDeclaration -> expr<UDeclarationsExpression> {