JetBrains/kotlin v1.4.20-RC

Kotlin 1.4.20-RC

on GitHub

Compiler

New Features

• KT-31567 Support special semantics for underscore-named catch block parameters

Performance Improvements

• KT-41741 NI: "AssertionError: Empty intersection for types" with generic Java collection
• KT-42195 NI: prohibitively long compilation time for values of nested data structures with type inference
• KT-42221 Native compiler never finishes frontend phase after migrating to Kotlin 1.4.10

Fixes

• KT-17691 Wrong argument order in resolved call with varargs
• KT-25114 Prohibit @JvmStatic on functions in private companions
• KT-33917 Prohibit to expose anonymous types from private inline functions
• KT-35870 Forbid secondary enum class constructors which do not delegate to the primary constructor
• KT-39098 NI: parameter of anonymous function can be inferred to Any? if another parameter's type is specified
• KT-41176 NI with Gson: "ClassCastException: java.util.ArrayList cannot be cast to java.lang.Void"
• KT-41194 ClassCastException on returning Result.failure from lambda within suspend function
• KT-42438 NI: ClassCastException: cannot be cast to java.lang.Void caused by when statement in run function
• KT-42699 False positive NON_JVM_DEFAULT_OVERRIDES_JAVA_DEFAULT diagnostic in new jvm-default modes
• KT-42706 Kotlin 1.4 infers generic is Nothing instead of actual Foo class (Android project)

IDE

• KT-42883 No highlighting for elements marked as @deprecated in stdlib

IDE. Decompiler, Indexing, Stubs

• KT-41646 "AssertionError: ContentElementType: FILE"; Code analysis never finishes on some files from my project

IDE. Gradle Integration

• KT-38830 addTransitiveDependenciesOnImplementedModules performance is slowing down Android Studio Gradle Sync

IDE. Inspections and Intentions

• KT-43037 Disable "Incomplete destructuring declaration" in 1.4.20

JavaScript

• KT-37829 Kotlin JS IR: "Properties without fields are not supported" for companion objects
• KT-39740 KJS / IR: Can't use Serializable and JsExport annotations at the same time

Libraries

• KT-19192 Provide file system extensions/APIs based on java.nio.file.Path
• KT-41837 Remove @ExperimentalStdlibApi from CancellationException

Tools. CLI

• KT-41916 Add JVM target bytecode version 15

Tools. Gradle. JS

• KT-42494 KJS / Gradle: "Configuration cache state could not be cached" caused by Gradle configuration cache

Tools. Gradle. Native

• KT-42531 Gradle task "podGenIos" fails if a Pod with a static library is added.