Hi ! Is there any way to force Tree Shaking in Kotlin/JVM ? I have this really simple code

private inline fun execute(block: () -> Unit) = block()

fun main() {
	execute { println("test") }
}

But when I see the Bytecode, it creates an

execute

static method on the MainKt class but never use it, is there a way to say to the compiler to not generate this method and just inline ?

ProGuard or r8 can

Does any of these works for PC ? For both it saids that it's optimizers for Android Apps, I'm not doing an Android app but a Game on PC

yes, both work for JVM. I have an example at https://github.com/ephemient/utf-8b

And it's only possible with a third party library, not with the Kotlin or JVM compiler ?

@jw has a writeup about using r8 for this purpose: https://jakewharton.com/shrinking-a-kotlin-binary/

Yes but I just want to optimize my jar so it's lighter

maybe take out

kotlinx-coroutines-debug

from your production dependencies, otherwise you'll have to fill in some implementation for that annotation class to satisfy r8

But I only have this dependency

implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.0")

then check your dependency graph, you may be pulling in

kotlinx-coroutines-test

or

-debug

from somewhere

Hm, why does

crossinline

do not work?

private inline fun execute(crossinline block: () -> Unit) = block()

fun main() {
	execute { println("test") }
}

crossinline has no effect here because its purpose is completely unrelated. Kotlin generates a non-inline function for the purposes of reflection.

Ah, thanks!

Basically yes compilers in general try not to optimize as much for the purposes of bing able to use reflection and testing later on. Minifiers are then used to remove dead bytecodes

ProGuard also works for non-Android apps (it actually started out as a Java optimizer/shrinker 20 years ago, before Android) https://www.guardsquare.com/manual/setup/gradle