original.name="UnionType_Invalid_4"
======
>>> main.whiley
type IntBoolList is int[] | bool[]

function f(int[] xs) -> int[]:
    return xs

public export method test() -> int[]:
    IntBoolList x = (IntBoolList) [1, 2, 3]
    x[0] = false
    IntBoolList y = [1, 2, 3]
    y[0] = false
    return f(x)
---
E402 main.whiley 8,4
E400 main.whiley 10,11:15
E400 main.whiley 11,13