Optionals Should Conditionally Conform to Hashable

[rullie]

With Swift 4.1, on XCode 9.3 beta (9Q98q)

The following does not compile:

struct MyStruct: Hashable {
    let prop1: String?
}

error: type 'MyStruct' does not conform to protocol 'Hashable'

Is this due to String? / Optional not being hashable?

[lorentey (Karoy Lorentey)]

Indeed it is! We are discussing adding Hashable conformance to Optional on this thread:

Let Optional, Dictionary and Array conditionally conform to Hashable

Hi all, I just tried out Swift 4.1 synthesis of Equatable and Hashable. This is truly awesome, and removes boilerplate code that is bothersome to maintain. In case of Hashable it also eliminates the need for the developer to know and understand the intricacies of creating good hashes. When synthesizing Hashable I noticed that Array, Optional and Dictionary do not conditionally conform to Hashable, while Set (unconditionally) does. While it is fairly easy to add the support through condition…

[rullie]

Ah, thank you.