1

why does this not work when the struct is local to a function?

func f() 
{
    struct Pair:Hashable, Comparable
    {
        let x:Int, y:Int 
        
        static 
        func < (lhs:Pair, rhs:Pair) -> Bool 
        {
            if lhs.y < rhs.y 
            {
                return true 
            }
            else if lhs.y == rhs.y 
            {
                return lhs.x < rhs.x
            }
            else 
            {
                return false
            }
        }
    }
}

:3:12: error: type 'Pair' does not conform to protocol 'Comparable'
    struct Pair:Hashable, Comparable
           ^
2

Certainly a bug related to operator functions in conformances. IteratorProtocol and a simple custom protocol work fine. Using a name instead of < or having a default implementation works too.

protocol P { static func < (lhs: Self, rhs: Self) -> Bool }

func f() {
  struct B: P {
    static func < (lhs: B, rhs: B) -> Bool {return true} // The error
  }
}
1 Like
3

This looks like the same bug as the one that's being discussed here: Hashable struct in function.

3 Likes
4

@Max, have you filed the bug with the Hashable struct inside a function yet?