Kotlin v1.5RC released, JVM-based programming language

Compiler

New Features

• KT-28791 Kotlin serialization with inline classes
• KT-43920 Support loading binary Java annotations on fields

Performance Improvements

• KT-44153 NI: Low Memory and IntelliJ hangs when quotes in split() are missed
• KT-45410 JVM / IR: Extreme performance regression on arithmetic operations inside a loop

Fixes

• KT-35224 It’s possible to pass non-spread arrays after arguments with SAM-conversion
• KT-36853 IR: UninitializedPropertyAccessException on tailrec with object expression in default argument
• KT-41056 Increase stub version due to new “contract” keyword
• KT-43887 Problem with FunctionReferenceLowering$FunctionReferenceBuilder in kotlin native
• KT-44210 KJS / IR: “AssertionError: Undefined parameter referenced: defined” caused by plus assign operators in build blocks
• KT-44947 Sealed interfaces: Sealed fun interface leads to “NoWhenBranchMatchedException”
• KT-44993 JVM IR: VerifyError on getfield with Kotlin generic field and elvis operator
• KT-45139 Inline class: AssertionError: Expected top level inline class
• KT-45195 JVM IR: annotation methods are generated as default interface methods if allopen is used
• KT-45446 JVM / IR: NullPointerException caused by unreachable code and comparison
• KT-45721 JVM / IR: “Unbound symbols not allowed” caused by class reference in sequence lambda
• KT-45853 JVM / IR: “Accidental override” caused by inheriting Throwable.getCause from Java interface
• KT-45861 Turning warnings into errors for calls with type parameters annotated by @OnlyInputTypes
• KT-45868 JVM IR: ClassCastException with SAM function in init block when SAM is generated via invokedynamic
• KT-45920 JVM IR: “Accidental override” on redefining get() in custom Map class
• KT-45963 JVM / IR: “AbstractMethodError: Receiver class does not define or inherit an implementation of the resolved method” in Dokka tests
• KT-45967 JVM IR: “IllegalAccessError” with invokedynamic to Java SAM over callable reference to private function
• KT-45982 Wrong subtyping result on captured types with postponed type variables

IDE. Inspections and Intentions

• KT-38155 Lift assignment out of ‘if’ produces type mismatch without manually adding a semicolon

JavaScript

• KT-44796 KJS / IR: default parameter of function with @JsName leads to “RangeError: Maximum call stack size exceeded”

Libraries

• KT-39177 Make CharCategory available in common multiplatform code
• KT-43772 Kotlin/Native unfinished workers detected.

Tools. Gradle

• KT-43605 Kotlin Gradle Plugin 1.4.20 undeclared system property reads cause problems with Gradle configuration cache enabled
• KT-44462 Kotlin Gradle plugin creates compile configuration with Gradle 7.0
• KT-44949 Compatibility with Gradle 7.0
• KT-44957 gradle – target.compilations seems to be deprecated
• KT-45340 Update minimal supported version of Kotlin Gradle Plugin to 6.1

Tools. Gradle. Multiplatform

• KT-44900 Support gradle configuration cache with kotlin.multiplatform plugin

Tools. kapt

• KT-43686 KaptWithoutKotlincTask should use @CompileClasspath for kotlinStdlibClasspath for cache relocateability.
• KT-44130 KAPT changes field order in 1.4.30-M1