meldestelle/docs/02_Reference/Tech_Stack/Kotlin_2-3-0_ReleaseNotes.md

What's new in Kotlin 2.3.0 | Kotlin Documentation

Quelle: Original Kotlin Documentation Datum des Dokuments: 16. Dezember 2025 Kontext: Dieses Dokument dient als Referenz für die im Projekt verwendete Kotlin-Version.

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The Kotlin 2.3.0 release is out! Here are the main highlights:

• Language: More stable and default features, unused return value checker, explicit backing fields, and changes to context-sensitive resolution.
• Kotlin/JVM: Support for Java 25.
• Kotlin/Native: Improved interop through Swift export, faster build time for release tasks, C and Objective-C library import in Beta.
• Kotlin/Wasm: Fully qualified names and new exception handling proposal enabled by default, as well as new compact storage for Latin-1 characters.
• Kotlin/JS: New experimental suspend function export, LongArray representation, unified companion object access, and more.
• Gradle: Compatibility with Gradle 9.0 and a new API for registering generated sources.
• Compose compiler: Stack traces for minified Android applications.
• Standard library: Stable time tracking functionality and improved UUID generation and parsing.

Language

Kotlin 2.3.0 focuses on feature stabilization, introduces a new mechanism for detecting unused return values, and improves context-sensitive resolution.

Stable features

The following features have now graduated to Stable:

• Support for nested type aliases
• Data-flow-based exhaustiveness checks for when expressions

Features enabled by default

• Support for return statements in expression bodies with explicit return types is now enabled by default.

Experimental: Unused return value checker

Kotlin 2.3.0 introduces the unused return value checker to help prevent ignored results. It warns you whenever an expression returns a value other than Unit or Nothing and isn't used.

Experimental: Explicit backing fields

A new syntax for explicitly declaring the underlying field that holds a property's value, simplifying the common backing properties pattern.

Kotlin/JVM: Support for Java 25

Starting with Kotlin 2.3.0, the compiler can generate classes containing Java 25 bytecode.

Kotlin/Native

• Improved Swift Export: Direct mapping for native enum classes and variadic function parameters.
• C and Objective-C Library Import is in Beta: Better diagnostics for binary compatibility issues.
• Faster Build Time: Up to 40% faster release builds, especially for iOS targets.

Kotlin/Wasm

• Fully Qualified Names Enabled by Default: KClass.qualifiedName is now available at runtime without extra configuration.
• Compact Storage for Latin-1 Characters: Reduces metadata and binary size.
• New Exception Handling for wasmWasi: Enabled by default for better compatibility with modern WebAssembly runtimes.

Kotlin/JS

• Experimental Suspend Function Export: Export suspend functions directly to JavaScript using @JsExport.
• BigInt64Array for LongArray: Simplifies interop with JavaScript APIs that use typed arrays.
• Unified Companion Object Access: Consistent access to companion objects in interfaces across all JS module systems.
• @JsStatic in Interfaces: Now supported in interfaces with companion objects.
• @JsQualifier on individual declarations: Can now be applied to individual functions and classes.
• @JsExport.Default: New annotation for generating JavaScript default exports.

Gradle

• Fully compatible with Gradle 7.6.3 through 9.0.0.
• Minimum supported Android Gradle plugin version is now 8.2.2.
• New experimental API for registering generated sources.

Standard library

• Stable Time Tracking: kotlin.time.Clock and kotlin.time.Instant are now stable.
• Improved UUID Generation: New functions like Uuid.parseOrNull(), Uuid.generateV4(), and Uuid.generateV7().

Compose compiler

• Stack Traces for Minified Android Apps: The compiler now outputs ProGuard mappings for Compose stack traces when applications are minified by R8.

(Dies ist eine gekürzte Zusammenfassung. Das Originaldokument enthält detailliertere Informationen und Code-Beispiele.)