Hi Guillaume, Without going into details, it looks like the Swift wrappers for dispatch_time_t are very, very broken. In short, dispatch_time_t (in the C world) is intentionally documented as an opaque type, but the Swift wrappers assume otherwise and jump to wrong conclusions about the implementation of the type. What this means in practice is that you should avoid the DispatchTime comparison APIs for now.
Dave > On Aug 26, 2017, at 15:21, Guillaume Lessard via swift-dev > <swift-dev@swift.org> wrote: > > On Linux (Ubuntu 16.04) and swift distributions from 3.0.2 to the latest 4.0 > snapshot, I’m seeing incorrect behaviour involving DispatchTime.distantFuture: > (also: https://bugs.swift.org/browse/SR-5706) > > *** > import Dispatch > > let now = DispatchTime.now() > let future = DispatchTime.distantFuture > assert(now != future, "this is not the distant future") > > print(String(now.rawValue, radix: 16)) // 1c20d6bbd3a (e.g.) > print(String(future.rawValue, radix: 16)) // ffffffffffffffff > > print(now < future) // false (incorrect) > print(future < now) // false > > print(now > future) // false > print(future > now) // false (incorrect) > > extension DispatchTime { > public static func compare(_ a: DispatchTime, happensBefore b: DispatchTime) > -> Bool { > return a.rawValue < b.rawValue > } > } > > print(DispatchTime.compare(now, happensBefore: future)) // true > print(DispatchTime.compare(future, happensBefore: now)) // false > *** > > Note that the static func I defined above is essentially the same as the > less-than operator as defined in the libdispatch overlay: > <https://github.com/apple/swift/blob/92f750aa3c3c4dce47eb55068850f3d1127b16bd/stdlib/public/SDK/Dispatch/Time.swift#L73> > > Also, there is a test that should catch this > problem:<https://github.com/apple/swift/blob/92f750aa3c3c4dce47eb55068850f3d1127b16bd/test/stdlib/Dispatch.swift#L104> > > > Could this operator func somehow be called correctly during testing, but > incorrectly at runtime? > (In other words, I don’t see where the fix needs to be.) > > Thanks, > Guillaume Lessard > > _______________________________________________ > swift-dev mailing list > swift-dev@swift.org > https://lists.swift.org/mailman/listinfo/swift-dev _______________________________________________ swift-dev mailing list swift-dev@swift.org https://lists.swift.org/mailman/listinfo/swift-dev
