Kotlin Multiplatform Apr 30, 2025 Pre-release

v2.2.0-Beta2

What's New

Kotlin 2.2.0-Beta2 delivers significant K2 compiler stability with 50+ Analysis API and FIR fixes, enhances Compose compiler with new default optimizations, and improves WebAssembly and JVM backends. The release adds Jakarta nullability support, JVM 24 bytecode targeting, and IR inliner improvements while dropping pre-1.6 language features and refining metadata handling for better tooling integration.

Highlights

Breaking Changes

  • Language versions 1.6 and 1.7 dropped from compiler
  • JvmDefaultWithoutCompatibility now errors when used with -Xjvm-default=all flag
  • Obsolete @JvmDefaultWithCompatibility error removed from interfaces

Deprecations

  • hasAnnotations flag in kotlin-metadata deprecated, replaced with JVM-only hasAnnotationsInBytecode
  • CreateNSStringFromKString and CreateKStringFromNSString hidden or removed for Kotlin/Native
  • Declaration of atomic properties marked with @PublishedApi now errors instead of warns

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