How to refer to Swift's `Clock` type in a generic type parameter constraint?

[lawrence-forooghian]

If I have a generic type parameter called Clock, how can I express that this type should implement Swift's Clock protocol? It's not clear to me what's the correct way to qualify the type name, given that Swift.Clock does not exist, and I assume, given the underscore, that I shouldn't be writing _Concurrency.Clock.

[Danny]

Implicitly imported types & namespace priority

_Concurrency.Task is the correct invocation. the underscore is part of the module name, do not fear the underscore just because it’s there. however, you may eventually experience some source breakage once the core team decides to drop the underscore, similar to _Distributed -> Distributed. but this would also happen if you used the typealias.

[lawrence-forooghian]

Thank you!

[Slava_Pestov]

Given that module interface files refer to the _Concurrency module, any source breakage of this kind would be staged over a period of time.

[xwu (Xiaodi Wu)]

If you are worried about the underscore, in a separate file within your project you can define your own type alias of Clock—for example:

typealias ConcurrencyClock /* or whatever you want to call it */ = Clock

You can then use that alias everywhere in your project.

[lawrence-forooghian]

Good point, I hadn't thought of that!