How to apply -Xopt-in=kotlin.ExperimentalUnsignedTypes to all subprojects?

Question

I have a project with multiple subprojects that use the kotlin-multiplatform plugin or the kotlin-js plugin and I want to use the experimental unsigned types in all of them.

So far I've tried this, which doesn't work:

subprojects {
    tasks.withType<KotlinCompile>().all {
        kotlinOptions.freeCompilerArgs += "-Xopt-in=kotlin.ExperimentalUnsignedTypes"
    }

    extensions.findByType<KotlinMultiplatformExtension>()?.sourceSets {
        all {
            languageSettings.useExperimentalAnnotation("kotlin.ExperimentalUnsignedTypes")
        }
    }
}

Is there a way to add the kotlin compiler arg -Xopt-in=kotlin.ExperimentalUnsignedTypes to all subprojects in Gradle?

Answer 1

I've reached this point with trial and error, so I'm not sure this is the right approach.

I had a multiproject build with some multiplatform, JVM, and JS subprojects, and I wanted to enable the kotlin.RequiresOptIn annotation. So I ended up setting this compiler argument for all kinds of kotlin compilation tasks:

subprojects {
    val compilerArgs = listOf("-Xopt-in=kotlin.RequiresOptIn")
    tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
        kotlinOptions.jvmTarget = "1.8"
        kotlinOptions.freeCompilerArgs += compilerArgs
    }

    tasks.withType<org.jetbrains.kotlin.gradle.tasks.Kotlin2JsCompile> {
        kotlinOptions.freeCompilerArgs = compilerArgs
    }

    tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompileCommon> {
        kotlinOptions.freeCompilerArgs = compilerArgs
    }
}

I guess the same approach could work for ExperimentalUnsignedTypes.