//@target: ES6
function foo(...s: (symbol | string)[]) { }
class SymbolIterator {
    next() {
        return {
            value: Symbol(),
            done: false
        };
    }

    [Symbol.iterator]() {
        return this;
    }
}

class _StringIterator {
    next() {
        return {
            value: "",
            done: false
        };
    }

    [Symbol.iterator]() {
        return this;
    }
}

foo(...new SymbolIterator, ...new _StringIterator);