mirai/backend/codegen/build.gradle.kts

import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

plugins {
    kotlin("jvm") version "1.4-M2"
    kotlin("plugin.serialization") version "1.4-M2"
    id("java")
}

kotlin {
    sourceSets {
        all {
            languageSettings.useExperimentalAnnotation("kotlin.Experimental")
            languageSettings.useExperimentalAnnotation("kotlin.OptIn")
            languageSettings.progressiveMode = true
            languageSettings.languageVersion = "1.4"
            languageSettings.apiVersion = "1.4"
            languageSettings.useExperimentalAnnotation("net.mamoe.mirai.utils.MiraiInternalAPI")
            languageSettings.useExperimentalAnnotation("kotlin.ExperimentalUnsignedTypes")
            languageSettings.useExperimentalAnnotation("kotlin.experimental.ExperimentalTypeInference")
            languageSettings.useExperimentalAnnotation("kotlin.contracts.ExperimentalContracts")
        }
    }
}

dependencies {
    api(kotlin("stdlib-jdk8", "1.4-M2"))
}

val compileKotlin: KotlinCompile by tasks
compileKotlin.kotlinOptions {
    jvmTarget = "1.8"
}
val compileTestKotlin: KotlinCompile by tasks
compileTestKotlin.kotlinOptions {
    jvmTarget = "1.8"
}
java {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_1_8
}
tasks.withType(JavaCompile::class.java) {
    options.encoding = "UTF8"
}