Open Radar

 
Summary:
I’ve created a type copied and pasted from the documentation for the Hashable protocol, and trying to use arrays of them in a Set fails.

Steps to Reproduce:
1. Create a GridPoint type:

/// A point in an x-y coordinate system.
struct GridPoint {
    var x: Int
    var y: Int
}

2. Add an extension to make GridPoint conform to Hashable:

extension GridPoint: Hashable {
    var hashValue: Int {
        return x.hashValue ^ y.hashValue
    }
    
    static func == (lhs: GridPoint, rhs: GridPoint) -> Bool {
        return lhs.x == rhs.x && lhs.y == rhs.y
    }
}

3. Use this new type in a function that returns a Set of Arrays of GridPoints:

func routesToBottomRight(inGridOfSize size: Int) -> Set<[GridPoint]> {
    return Set<[GridPoint]>()
}

Expected Results:
The above code will compile. Since GridPoint implements Hashable, [GridPoint] will implement Hashable.

Actual Results:
Error message: Type '[GridPoint]' does not conform to protocol 'Hashable'

Version:
iOS version 10.0 (14A5341a)