private struct UNIXPath: Path {
    // ...
    // Fast path
    init(normalizingAbsolutePath path: String) {
        // ...
        if !mayNeedNormalization(absolute: path) {
            self.init(string: path) 
            // no return to take effect.
        }
        // ...

        self.init(string: result)
    }
}

struct Test {
    let string: String


    init(string1: String) {
        self.string = string
    }


    init(string2: String) {
        if string2 == "1" {
            self.init(string1: string2 + " with if")
            // return
        }
        self.init(string1: string2 + " without if")
    }
}

print(Test(string2: "1").string) // '1 without if', which should be '1 with if' when add return.
print(Test(string2: "2").string) // '2 without if'