Ability to subclass NetworkDataResourceService broken in Swift 5.2

[Jon889]

In Swift 5.2 there is a change that prevents changing the generic requirements in an overridden method. Which completely breaks our use of subclassing NetworkDataResourceService.

https://forums.swift.org/t/method-override-with-a-generic-signature-with-requirements-not-imposed-by-the-base-method/33593

Is there any ideas on how to resolve this?

[theblixguy]

I left a comment on your post with an explanation. Please let me know (on the forums) if you have any other questions about the change.

You can continue to use Swift 5.1 though.

[ahmedAlmasri]

I have the same issue any idea? +1

[theblixguy]

Your options are:

1. Stay on Swift 5.1.
2. Perform a runtime cast (i.e. if let resource = resource as? SomeOtherResourceProtocol) to conditionally check the conformance (but it wont work if your protocol has Self or associatedtypes) and then do something.
3. Change the design/architecture of your code.

[ahmedAlmasri]

I'm using a swift 5.1 but still, have a same issue , do can you see my code?

[theblixguy]

To clarify, if you’re doing the above then the problem is with your code rather than the compiler. My suggestion to stay on Swift 5.1 is only temporary (while you investigate other approaches), the right way to fix the problem is to rewrite the code in a way that doesn’t break Liskov.

I implemented the changes in 5.2, so it’s not possible for the code to stop compiling in 5.1, so I assume you have a different but related problem? If you could show your code then I may be able to offer some suggestions.

[ahmedAlmasri]

Thank you for replay

My question: https://stackoverflow.com/q/60710024/9315978

[theblixguy]

Seems like some sort of alignment issue (at least in debug mode), in release mode it runs fine on Swift 5.1.

Anyway, it won't work on 5.2 because the code isn't correct. You're adding a new Decodable constraint when overriding responseBodyConverter but anyone can pass something that doesn't conform to Decodable via the base class's responseBodyConvertor down to the convert method, leading to a runtime crash.

[ahmedAlmasri]

@theblixguy thank you so much I fixed it using a check the types