=== tests/cases/conformance/expressions/typeGuards/TypeGuardWithArrayUnion.ts ===
class Message {
>Message : Message

    value: string;
>value : string
}

function saySize(message: Message | Message[]) {
>saySize : (message: Message | Message[]) => number
>message : Message | Message[]
>Message : Message
>Message : Message

    if (message instanceof Array) {
>message instanceof Array : boolean
>message : Message | Message[]
>Array : ArrayConstructor

        return message.length;  // Should have type Message[] here
>message.length : number
>message : Message[]
>length : number
    }
}