interface Some

object O1 : Some

object O2 : Some

enum class SomeEnum(val x: Some) {
    FIRST(O1) {
        override fun check(y: Some): Boolean = true
    },
    SECOND(O2)  {
        override fun check(y: Some): Boolean = y == O2
    };

    abstract fun check(y: Some): Boolean
}

enum class E {
    A; // no constructor call needed
    constructor()
}

enum class EnumClass {
    E1 {
        override fun foo() = 1
        override val bar: String = "a"
    },

    <!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>E2<!> {

    },

    <!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>E3<!>();

    abstract fun foo(): Int
    abstract val bar: String
}