// @strictNullChecks: true

function f1(s: string) {
    if (s === "foo") {
        s;  // "foo"
    }
    if (s === "foo" || s === "bar") {
        s;  // "foo" | "bar"
    }
}

function f2(s: string) {
    switch (s) {
        case "foo":
        case "bar":
            s;  // "foo" | "bar"
        case "baz":
            s;  // "foo" | "bar" | "baz"
            break;
        default:
            s;  // string
    }
}

function f3(s: string) {
    return s === "foo" || s === "bar" ? s : undefined;  // "foo" | "bar" | undefined
}

function f4(x: number) {
    if (x === 1 || x === 2) {
        return x;  // 1 | 2
    }
    throw new Error();
}

function f5(x: number, y: 1 | 2) {
    if (x === 0 || x === y) {
        x;  // 0 | 1 | 2
    }
}

function f6(x: number, y: 1 | 2) {
    if (y === x || 0 === x) {
        x;  // 0 | 1 | 2
    }
}

function f7(x: number | "foo" | "bar", y: 1 | 2 | string) {
    if (x === y) {
        x;  // "foo" | "bar" | 1 | 2
    }
}

function f8(x: number | "foo" | "bar") {
    switch (x) {
        case 1:
        case 2:
            x;  // 1 | 2
            break;
        case "foo":
            x;  // "foo"
            break;
        default:
            x;  // number | "bar"
    }
}