Kotlin Multiplatform v2.5.0-Beta2 Release Notes & Developer Guide

Kotlin v2.5.0-Beta2 advances Multi-Field Value Classes to alpha, stabilizes IntrinsicConstEvaluation, and enables the Return Value Checker by default. The release introduces Rich Errors infrastructure in the compiler frontend, significant Analysis API redesigns (KaType, KaScope), and multiple Kotlin/Wasm performance and correctness fixes including default range checks. Compose compiler improvements add rich callable references for @Composable functions while removing deprecated feature flags, alongside continued cleanup dropping older language version and K1 scripting support.

Highlights

• Alpha release of Multi-Field Value Classes with Analysis API and codegen support
• Return Value Checker enabled by default in the compiler
• IntrinsicConstEvaluation feature made stable
• Rich Errors feature introduced across Parser, FIR Tree, Resolution, and Checkers
• K/Wasm range checks turned on by default, improving safety
• Compose compiler adds rich callable references for @Composable functions
• Analysis API KaType hierarchy redesigned and KaScopes stabilized