Intellij refuses to set the Kotlin target jvm to 1.8?

Question

ParallelStreams.kts:41:15: error: calls to static methods in Java interfaces are prohibited in JVM target 1.6. Recompile with '-jvm-target 1.8'
IntStream.range(0,10).parallel().forEach{a ->
         ^

Ok ... I'm not trying to compile for 1.6.

File > Project Structure > Project has project sdk 1.8 and language level 8.

File > Project Structure > Modules > Kotlin has target platform: JVM 1.8.

File > Project Structure > Facets > Kotlin has target platform: JVM 1.8.

File > Settings > Compiler > Kotlin Compiler has target jvm version 1.8.

My gradle build file ...

plugins {
    id 'org.jetbrains.kotlin.jvm' version '1.3.0'
}

group 'foo'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

dependencies {
    //kotlin
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
    implementation "org.jetbrains.kotlin:kotlin-script-runtime:1.3.0"

    //networking
    implementation 'com.mashape.unirest:unirest-java:1.4.9'
}

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
    kotlinOptions.jvmTarget = "1.8"
}

I'm running out of places to check for 1.8.

And yes, I have tried invalidating the cache and restarting Intellij. It does nothing to resolve this issue.

Answer 1

Add sourceCompatibility and targetCompatibility for Java 1.8:

plugins {
  id 'org.jetbrains.kotlin.jvm' version '1.3.0'
}

group 'foo'
version '1.0-SNAPSHOT'

repositories {
  mavenCentral()
}

// Add compatibility
sourceCompatibility = JavaVersion.VERSION_1_8
targetCompatibility = JavaVersion.VERSION_1_8


dependencies {
  //kotlin
  implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
  implementation "org.jetbrains.kotlin:kotlin-script-runtime:1.3.0"

  //networking
  implementation 'com.mashape.unirest:unirest-java:1.4.9'
}

compileKotlin {
  kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
  kotlinOptions.jvmTarget = "1.8"
}

Answer 2

With .kts just use this:

tasks {
    withType<KotlinCompile> {
        kotlinOptions.jvmTarget = "1.8"
    }
}

// I am using latest dsl and gradle 
val kotlinVersion = "1.3.30"
val gradleVersion = "5.4+"