original.name="UnionType_Invalid_5"
======
>>> main.whiley
type IntList is {int op, bool[] rest} | {int[] op, int mode}

function f(IntList x) -> IntList:
    return x

public export method test() :
    IntList x = (IntList) {op: 1, rest: [false]}
    x.op = [1, 2, 3]
    IntList y = {op: 1, rest: [false]}
    y.op = [1, 2, 3]    
    f(x)
---
E403 main.whiley 8,4
E400 main.whiley 10,11:19