struct S {
    let x: Int
}

extension S {
    init(a: Int) {
        x = a // error: 'let' property ‘x’ may not be initialized directly; use "self.init(...)" or "self = ..." instead
        self.init(x: a)
    }
    
    init(b: Int) {
        self.init(x: b)
        x = b // error: 'let' property ‘x’ may not be initialized directly; use "self.init(...)" or "self = ..." instead
    }
}

extension S {
    init(c: Int) {
        x = c
        x = c // error: immutable value 'self.x' may only be initialized once
              // fix-it: change 'let' to 'var' to make it mutable
    }
}

extension S {
    init(d: Int) {
        x = d // error: immutable value 'self.x' may only be initialized once
        self.init(x: d) // info: immutable value 'self.x' will be reinitialized here
    }
    
    init(e: Int) {
        self.init(x: e) // info: immutable value 'self.x' has been initialized here
        x = e // error: immutable value 'self.x' may only be initialized once
    }
}