Kotlin 函数引用和lambdas

I'm facing a compile error when trying to use lambdas / function references with kotlin:

class Foo {

    fun getFilteredList(){
        val numbers = listOf(1, 2, 3)
        numbers.filter(::isOdd) // prints [1, 3]
    }

    fun isOdd(x: Int): Boolean = x % 2 != 0

}

但我得到一个编译时错误，说类型不匹配:

Error:(18, 16) Gradle: Type inference failed: inline fun kotlin.Iterable.filter(predicate: (T) -> kotlin.Boolean): kotlin.List cannot be applied to receiver: kotlin.List arguments: (kotlin.reflect.KFunction2) Error:(18, 23) Gradle: Type mismatch: inferred type is kotlin.reflect.KFunction2 but (kotlin.Int) -> ??? was expected Error:(18, 23) Gradle: Type mismatch: inferred type is kotlin.reflect.KFunction2 but (kotlin.Int) -> kotlin.Boolean was expected Error:(18, 25) Gradle: Left-hand side of a callable reference with a receiver parameter cannot be empty. Please specify the type of the receiver before '::' explicitly

I'm not sure what the error is nor what type I should specify explicitly before '::'

另一个问题:

class Bar {
    fun isOdd(x: Int): Boolean = x % 2 != 0
}

class Foo {

    fun getFilteredList(){
        val bar = Bar()
        val numbers = listOf(1, 2, 3)
        numbers.filter(bar::isOdd) // Use Bar's method
    }
}