Kotlin repeatable @annotations don't work on jdk-8

Question

I have declared a repeatable annotation @Parameter in kotlin as below:

@Repeatable
annotation class Parameter(val name: String);

but when I use it as below the compiler reports an Error:

Only annotations with SOURCE retention can be repeated on JVM version before 1.8

@Parameter("foo")
@Parameter("bar")
fun repeat() = 1;

I'm sure I'm working with jdk-8 in kotlin. and the option jvmTarget also is set to 1.8 for kotlin-1.1.2 gradle plugin.

Q: Why it doesn't works fine?

sourceCompatibility = 1.8
targetCompatibility = 1.8

compileKotlin {
    kotlinOptions{
        jvmTarget = "1.8"
    }
}

Answer 1

If I'm not mistaken, Kotlin compiler currently targets the JDK 1.6 class file format. This means that, on Java, it can't write multiple annotations to the class file.

While conceptually Kotlin supports multiple annotations, until there's proper 1.8 targeting, it can't do so because of the output restrictions.