I don’t understand why #unknown wouldn’t work in catch clauses.  In the absence 
of typed throws you can’t match on an enums case without the enums base:  you 
can’t use .foo, you have to use MyEnum.foo.

Similarly, catch wouldn’t allow .#unknown, it would require MyEnum.#unknown.  
This is perfectly well defined and just falls out of the model.

That said, I agree that the issue of source dependencies that might use this is 
a significant problem.  IMO, that argues strongly for “unknown default:” 
producing a warning.

-Chris

> On Jan 12, 2018, at 10:49 PM, Chris Lattner via swift-evolution 
> <swift-evolution@swift.org> wrote:
> 
> 
>> On Jan 12, 2018, at 3:08 PM, Jordan Rose <jordan_r...@apple.com> wrote:
>> 
>> Okay, I went back to `unknown case` in the proposal, but mentioned Chris's 
>> point very specifically: if the compiler emits an error, we should go with 
>> `case #unknown` instead. (I'm very strongly in the "warning" camp, though.)
> 
> Thanks!
> 
> Out of curiosity, why not “unknown default:”?  The “warning” behavior is a 
> customization of default, so this seems like a more logical model.  It also 
> fits into the existing Swift grammar, unlike “unknown case:” which requires 
> adding a new special case production.
> 
> -Chris
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

Reply via email to