[swift-evolution] Warning when omitting default case for imported enums

[Rien]

-1

Reason 1: the “negative” behaviour you describe is actually exactly what I want to happen.
Reason 2: Introducing a warning would also necessitate a warning suppression in order to have your code compile without warnings. But when you suppress, the purpose of the warning is nul and void.

PS: I would suggest not to use an enum in cases where this is really annoying and replace the enums with constants.
 
Regards,
Rien

Site: http://balancingrock.nl
Blog: http://swiftrien.blogspot.com
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> On 07 Feb 2017, at 16:12, Tanner Nelson via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Hello Swift Evolution,
> 
> I'd like to propose that a warning be emitted when default cases are omitted for enums from other modules. 
> 
> What this would look like:
> 
> OtherModule:
> ```
> public enum SomeEnum {
>     case one
>     case two
> }
> 
> public let global: SomeEnum = .one
> ```
> 
> executable:
> ```
> import OtherModule
> 
> switch OtherModule.global {
>     case .one: break
>     case .two: break
>     ^~~~~ ⚠︎ Warning: Default case recommended for imported enums. Fix-it: Add `default: break`
> }
> ```
> 
> Why:
> 
> Allowing the omission of a default case in an exhaustive switch makes the addition of a new case to the enum a breaking change. 
> In other words, if you're exhaustively switching on an enum from an imported library, the imported library can break your code by adding a new case to that enum (which the library authors may erroneously view as an additive/minor-bump change).
> 
> Background:
> 
> As a maintainer of a Swift framework, public enums have been a pain point in maintaining semver. They've made it difficult to implement additive features and have necessitated the avoidance of enums in our future public API plans.
> 
> Related Twitter thread: https://twitter.com/tanner0101/status/796860273760104454
> 
> Looking forward to hearing your thoughts.
> 
> Best,
> Tanner
> 
> Tanner Nelson
> Vapor 
> +1 (435) 773-2831
> 
> 
> 
> 
> 
> 
> 
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