havrikov / kotlin-java-annotation-issue

This project reproduces this issue in the Kotlin compiler: https://youtrack.jetbrains.com/issue/KT-43422

Kotlin Java Annotation Bug

This project serves as a reproducer for the issue KT-43422 with the Kotlin compiler.

TL;DR

Executing ./gradlew build succeeds when it should not.
You can examine the generated code in the build directory.

The bug

Given an annotation defined in Java, it is possible to compile Kotlin code that improperly uses it.

import java.lang.annotation.ElementType;
import java.lang.annotation.Target;

@Target(ElementType.FIELD)
public @interface ExampleJavaAnnotation {
    Class<?> value();
}

The following Kotlin class compiles without any complaints!

class KotlinPlayground {
    @ExampleJavaAnnotation("wrong type")
    private val foo: String = ""
    @ExampleJavaAnnotation(Nonexistent::class)
    internal val bar: Int = 42
    @ExampleJavaAnnotation(Any, Strange, java.util.List<*> + "of things", 42)
    val baz: Boolean = false
    @ExampleJavaAnnotation({ `an entire` -> borked(lambda) })
    var qux: Int? = null
}