Kotlin

Changelog

Backend. Wasm

• KT-82649 K/Wasm: Rewrite StringBuilder to use JsString
• KT-83995 K/Wasm: 2.3.0 -> 2.3.20-Beta1 degradation in arrow tests
• KT-83839 K/Wasm: CMP. Load time on Safari significantly increased with Kotlin = 2.3.20-Beta1

Compiler

• KT-83372 compileDebugKotlinAndroid hangs in 2.3.0 with SQLDelight
• KT-83849 False-positive NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS for Optional.orElse(null) call
• KT-84192 "Member overrides diff

Changelog

Compiler

• KT-83984 Data races around kotlinx.serialization plugin protobuf extensions registration
• KT-83317 ClassCastException: with cast kotlin.UInt to java.lang.Number when defining constant
• KT-83031 K2: unstable resolution of EnhancedNullability from type-use NotNull in presence of unused code
• KT-81700 flaky overload resolution behaviors (false-positive errors, different final candidates, compile-time failures)
• KT-83983 Revert of KT-83081
• KT-83314 JSpecify @NullMarked changes Java equals(Object) to equals(Any?) causing override conflict in Kotlin 2.3
• KT-82863

ChangeLog

Compiler

• KT-83984 Data races around kotlinx.serialization plugin protobuf extensions registration
• KT-83983 Revert of KT-83081

Changelog

Analysis API. FIR

• KT-83467 Package-level JSpecify annotations are ignored when coming from jars or libraries
• KT-82846 AA: unresolved KtExpression.expressionType for the reference to the parameter with default value

Analysis API. Infrastructure

• KT-83173 Analysis API Tests: Library names with RC versions aren't sanitised

Analysis API. Surface

Performance Improvements

• KT-83694 Provide psi-based implementation of KaDeclarationSymbol#isExternal

Changelog

Compiler

• KT-83314 JSpecify @NullMarked changes Java equals(Object) to equals(Any?) causing override conflict in Kotlin 2.3
• KT-83317 ClassCastException: with cast kotlin.UInt to java.lang.Number when defining constant
• KT-83031 K2: unstable resolution of EnhancedNullability from type-use NotNull in presence of unused code
• KT-82863 @NoInfer regression since 2.2.20
• KT-82841 "kotlin.NoWhenBranchMatchedException" in when with !is check & non-sealed class in the middle

Changelog

Analysis API. FIR

New Features

• KT-78090 Implement stubs support for new conditional returns and holdsIn contracts

Fixes

• KT-80485 False positive UNRESOLVED_REFERENCE on nested interface from super-super class in the super type position inside an anonymous object
• KT-82948 'FirRegularClass' expected as a containing declaration, got 'FirTypeAliasImpl'
• KT-82057 K2. Cannot infer type parameter 'R' in Ktor routing post() function with explicit response type
• KT-82772

Changelog

Analysis API

• KT-80082 K2. False positive "Cannot resolve method" for self-bounded generic with wildcard return type in Java interop
• KT-80303 Move :native:analysis-api-klib-reader to :libraries:tools

Analysis API. Code Compilation

• KT-70860 K2 IDE / Kotlin Debugger: CCE “java.lang.String cannot be cast to java.lang.Void” on evaluating not-null variable on the line with assigning null to that var
• KT-78554 K2 IDE / Kotlin Debugger: ISE “No override for FUN IR_EXTERNAL_DECLARATION_STUB” on calling toString() for local class instance during evaluation
• KT-73201 K2 IDE: Error wh

Changelog

Compiler

• KT-82869 Green-to-Red change in 2.3 after prioritizing non-suspend-function-type overloads

Libraries

• KT-82901 Long.MIN_VALUE.milliseconds produces invalid denormalized Duration

Changelog

Compiler

• KT-82590 ClassCastException when instantiating class with generics implemented by fun interface and lambda

Tools. Compiler Plugin API

• KT-82563 Improve compiler error messages to identify incompatible plugins causing compilation failures

Changelog

Backend. Wasm

• KT-82075 K/Wasm: kotlin.wasm.internal.getSimpleName crashes on iOS Safari older than 26

Compiler

• KT-82138 Debugger: Cannot evaluate JvmInline value class parameter
• KT-78413 Kotlin Debugger: value classes as context parameters have incorrect names in Variables View during debugging
• KT-80549 Call of Java method with type parameter bounds: Expected FirResolvedTypeRef with ConeKotlinType but was FirJavaTypeRef
• KT-82132 False-positive type mismatch with -language-version 2.2<

Changelog

Analysis API

• KT-80082 K2. False positive "Cannot resolve method" for self-bounded generic with wildcard return type in Java interop

Analysis API. Code Compilation

• KT-70860 K2 IDE / Kotlin Debugger: CCE “java.lang.String cannot be cast to java.lang.Void” on evaluating not-null variable on the line with assigning null to that var

Analysis API. FIR

• KT-81378 Expected expression 'FirFunctionCallImpl' to be resolved caused by suspend {}
• KT-80473 Add events for tracking LL ac