Kotlin Version Support

Kotlin Version Support

Rebound supports Kotlin 2.0.x through 2.2.x and beyond. The Gradle plugin automatically selects the correct compiler artifact based on your project’s Kotlin version.

Version Matrix

Kotlin Version	Compiler Artifact	IR API	Auto-Selected
2.0.x	rebound-compiler	valueParameters, putValueArgument	Yes
2.1.x	rebound-compiler	valueParameters, putValueArgument	Yes
2.2.x+	rebound-compiler-kotlin-2.2	parameters, setArgumentByIndex	Yes

Why Two Compiler Artifacts?

The Kotlin 2.2 release introduced breaking changes to the Kotlin compiler’s IR API:

• IrFunction.valueParameters was renamed to IrFunction.parameters
• IrMemberAccessExpression.putValueArgument() was renamed to setArgumentByIndex()
• Several other accessor methods were renamed or restructured

These are source-incompatible changes. A single compiler plugin artifact cannot compile against both the 2.1.x and 2.2.x APIs. Rebound maintains two separate modules:

rebound-compiler

Located at rebound-compiler/ in the repository. Compiles against the Kotlin 2.0.x/2.1.x compiler API. Contains the full IR transformation logic using the pre-2.2 API surface.

rebound-compiler-k2

Located at rebound-compiler-k2/ as a standalone composite build. Contains the same transformation logic adapted to the Kotlin 2.2+ API surface. It is a composite build so it can declare its own Kotlin 2.2 dependency without forcing the rest of the project to use 2.2.

How Auto-Selection Works

The Gradle plugin detects the Kotlin version at apply time:

// Simplified from ReboundGradlePlugin
val kotlinVersion = project.extensions
    .findByType(KotlinProjectExtension::class.java)
    ?.coreLibrariesVersion

val compilerArtifact = if (kotlinVersion != null &&
    compareVersions(kotlinVersion, "2.2.0") >= 0) {
    "io.aldefy:rebound-compiler-kotlin-2.2:$reboundVersion"
} else {
    "io.aldefy:rebound-compiler:$reboundVersion"
}

The correct artifact is then added to the kotlinCompilerPluginClasspath configuration for the appropriate build variants.

Manual Override

In rare cases where auto-detection fails (e.g., custom Kotlin distributions), you can force the compiler artifact:

build.gradle.kts

dependencies {
    kotlinCompilerPluginClasspath("io.aldefy:rebound-compiler-kotlin-2.2:0.1.0")
}

This bypasses the Gradle plugin’s auto-selection. You must also add the runtime dependency manually:

dependencies {
    debugImplementation("io.aldefy:rebound-runtime:0.1.0")
}

Testing Across Versions

Rebound is validated against multiple Kotlin versions in the CI pipeline and on real apps:

App	Kotlin	Compose Compiler	Status
StickerExplode	2.1.0	1.5.x	Pass
HelloDistort	2.1.0	1.5.x	Pass
Lumen	2.0.21	1.5.x	Pass
Andromeda	2.2.20	2.0.x	Pass

If you encounter issues with a specific Kotlin version, open an issue on GitHub with the version details and build output.