[swift-dev] New warning message while switching on an enum

[Jordan Rose]

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 at 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
> 
> 
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