> On Nov 26, 2016, at 5:25 PM, Robert Widmann via swift-dev
> <swift-dev@swift.org> wrote:
>
> Hello all,
>
> I’ve seen and been a part of a number of conversations recently where talk of
> planning for “resilient enums”, or even just authors that ship frameworks
> that will eventually offer a binary option that export enum-based APIs. The
> consensus seems to be that the only safe way to deal with this situation is
> to always cover a `switch` statement with a default, regardless of whether
> the totality checker thinks you’ve covered all cases. Currently, the
> compiler warns when this is the case, as in stdlib
>
> extension ProcessTerminationStatus {
> var isSwiftTrap: Bool {
> switch self {
> case .exit(_):
> return false
> case .signal(let signal):
> return CInt(signal) == SIGILL || CInt(signal) == SIGTRAP
> default:
> // This default case is needed for standard library builds where
> // resilience is enabled
> return false
> }
> }
> }
>
> I think this warning doesn’t actually serve a purpose and I’d like to remove
> it, or at the very least curb it. Currently, I see three paths forward:
>
> 1) Do nothing.
> 2) Completely remove the diagnostic
> 3) Only emit the diagnostic when the case-tree is switching over enum(s)
> declared inside the current module.
Has the “resilient enum” thing been finalized, or is this kind of code just a
preventative measure?
Also, if “resilience” is a compiler flag, there's a fourth option: Disable the
warning on builds that have “resilience” enabled.
- Dave Sweeris
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