"as NSError" isn't a tautology, though—the original type is 'Error'. Additionally, the presence or absence of a warning shouldn't affect exhaustiveness analysis, which is currently an error when you get it wrong. Warnings are things you can build with and fix later.
Jordan > On May 9, 2017, at 11:22, Robert Widmann <devteam.cod...@gmail.com> wrote: > > We’ll warn if that kind of cast is a tautology, right? That leaves only the > dynamic casts, which can’t be assumed exhaustive. > > ~Robert Widmann > >> On May 9, 2017, at 2:13 PM, Jordan Rose <jordan_r...@apple.com >> <mailto:jordan_r...@apple.com>> wrote: >> >> It's neither a variable binding nor an expression pattern, right? It has to >> be compared against the original type to know whether it's exhaustive or >> not. (Consider "let error as NSError" in a catch clause, which should be >> considered exhaustive.) >> >> Jordan >> >>> On May 9, 2017, at 11:12, Robert Widmann <devteam.cod...@gmail.com >>> <mailto:devteam.cod...@gmail.com>> wrote: >>> >>> It’s mine, yep. It looks like it’s classifying the cast in the first >>> pattern as a variable binding instead of an expression pattern. I’ll push >>> a fix later. >>> >>> Thanks! >>> >>>> On May 9, 2017, at 1:52 PM, Jordan Rose <jordan_r...@apple.com >>>> <mailto:jordan_r...@apple.com>> wrote: >>>> >>>> That looks like a bug to me, since of course the first pattern won't >>>> always match. I suspect this is Robert's work on trying to make the >>>> exhaustive checks better, https://github.com/apple/swift/pull/8908 >>>> <https://github.com/apple/swift/pull/8908>. Thanks for catching this! >>>> >>>> Jordan >>>> >>>> >>>>> On May 9, 2017, at 07:09, Pushkar N Kulkarni via swift-dev >>>>> <swift-dev@swift.org <mailto:swift-dev@swift.org>> wrote: >>>>> >>>>> Hi there, >>>>> >>>>> I see a new warning message for switch statements on enums, like this >>>>> one: >>>>> >>>>> enum Test { >>>>> case one(Any) >>>>> case two >>>>> } >>>>> >>>>> let x: Test = .one("One") >>>>> switch x { >>>>> case .one(let s as String): print(s) >>>>> case .one: break >>>>> case .two: break >>>>> } >>>>> >>>>> enum.swift:9:10: warning: case is already handled by previous patterns; >>>>> consider removing it >>>>> case .one: break >>>>> >>>>> >>>>> I do not see this warning with the 04-24 dev snapshot. >>>>> >>>>> The warning goes away with the use of the wildcard pattern in the second >>>>> case: >>>>> >>>>> switch x { >>>>> case .one(let s as String): print(s) >>>>> case .one(_): break >>>>> case .two: break >>>>> } >>>>> >>>>> >>>>> I am wondering if this change is intentional, though it does make sense >>>>> to me. Can someone please point me to the related commit? >>>>> >>>>> Thanks in advance! >>>>> >>>>> Pushkar N Kulkarni, >>>>> IBM Runtimes >>>>> >>>>> Simplicity is prerequisite for reliability - Edsger W. Dijkstra >>>>> >>>>> >>>>> _______________________________________________ >>>>> swift-dev mailing list >>>>> swift-dev@swift.org <mailto:swift-dev@swift.org> >>>>> https://lists.swift.org/mailman/listinfo/swift-dev >>>>> <https://lists.swift.org/mailman/listinfo/swift-dev> >>>> >>> >> >
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