Sometime ago I published a library with Amper and ...

# amper

[Giorgi]

Sometime ago I published a library with Amper and used.

settings:
  kotlin:
    languageVersion: 2.2

now when I try to consume it from a Gradle project, the build fails

[Giorgi]

this is the error

e: file:///Users/Giorgi_Shalvashvili/Downloads/aaaaaaaaa/data/src/commonMain/kotlin/OverwatchPlayerSearchDataSource.kt:9:32 Class 'io.github.shalva97.overwatch_player_search_api.PlayerSearch' was compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler.

[Giorgi]

so what version of Kotlin should I use in Gradle project?

[Giorgi]

currently I have kotlin = "2.2.20-Beta1"

[joffrey]

Amper wasn't released with the 2.2 compiler yet, so you were most likely using Kotlin 2.1.20 (which is the compiler used since Amper 0.6.0).

The languageVersion set in the settings is a compiler option but doesn't change the actual Kotlin tool chain. When using a higher version than the compiler, it makes the compiler accept new experimental language constructs of future versions. This is probably why you're seeing this.

[joffrey]

You could maybe try using Kotlin 2.1.20 with the same language level setting on the consumer side.

[Giorgi]

Hi, I tried to add

kotlin {

    compilerOptions {
        languageVersion.set(org.jetbrains.kotlin.gradle.dsl.KotlinVersion.KOTLIN_2_2)
    }

but it did not work. How to set language version? I have 2 modules, both of them have it specified

[joffrey]

I believe this is the correct way on Gradle side. Did you switch the compiler to 2.1.20 as well?

[Giorgi]

yep

[joffrey]

Sorry to hear that. I'm not entirely sure why this is happening. Did you by any chance use some extra compiler options when producing the library? I faced a similar thing today because I had added -Xannotation-default-target=param-property, and then consumers gave me this error

[Giorgi]

nvm, fixed it. it was serialization plugin. I had kotlin("plugin.serialization") version "2.2.0"

[Giorgi]

works with kotlin("plugin.serialization") version "2.1.20"

[joffrey]

Ah good to know, thanks

[Giorgi]

🚀