Open Radar

 
Summary:
RawOptionSetType is primarily used to represent NS_OPTIONS enums from Objective-C. These options sets use a UInt as their underlying data type. UInt is hashable. RawOptionSetType, however, is not Hashable, nor is the type definition of its RawValue property, despite (as far as I can tell) all extant RawOptionSetTypes having Hashable RawValues.

Making RawOptionSetType Hashable would greatly improve interoperating between Cocoa libraries that treat NS_OPTIONS as sets of configuration parameters by allowing Swift libraries to collect options in Sets and Dictionaries.

Steps to Reproduce:
Attempt to make a Set of members of a RawOptionSetType type:
let options: Set<UIViewAnimationOptions> = [.LayoutSubviews, .TransitionFlipFromLeft]

Expected Results:
A set is constructed containing the specified values

Actual Results:
error: type 'UIViewAnimationOptions' does not conform to protocol 'Hashable'

Notes:
As Swift protocols cannot be extended, it is impossible for external developers to add Hashable to RawOptionSetType. Hashable can be implemented on a case-by-case basis, but this is not a viable long-term solution:
extension UIViewAnimationOptions: Hashable {
    public var hashValue: Int { return rawValue.hashValue }
}