[swift-evolution] #selector and Void methods

[Jordan Rose]

> On Mar 23, 2016, at 10:11, Joe Groff via swift-evolution <swift-evolution at swift.org> wrote:
> 
>> 
>> On Mar 22, 2016, at 8:49 PM, Brent Royal-Gordon via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> So, today is day 2 of Swift 2.2 being in the hands of mere mortals. This evening, I walked into my weekly NSCoder Night meeting and talked to a pretty experienced developer struggling with this:
>> 
>> 	class EditEventViewController: UIViewController {
>> 		...
>> 		@IBAction func cancel(sender: AnyObject?) {
>> 			cancel()
>> 		}
>> 		func cancel() {
>> 			// actual canceling logic is here
>> 		}
>> 	}
>> 	
>> 	class EditEventContainerViewController: UIViewController {
>> 		...
>> 		func prepareForSegue(_ segue: UIStoryboardSegue, sender sender: AnyObject?) {
>> 			switch segue.identifier {
>> 				...
>> 				let cancelButton = UIBarButtonItem(barButtonSystemItem: .Cancel, target: nil, action: nil)
>> 				cancelButton.target = vc
>> 				cancelButton.action = #selector(vc.cancel)	// This is the problem line
>> 				...
>> 			}
>> 		}
>> 	}
>> 		
>> `vc.cancel` was, of course, ambiguous, and the SE-0021 `vc.cancel(_:)` syntax can't select a Void function. I had to explain how to use `as Void -> Void` to select the right version.
>> 
>> This is merely an anecdote, but I think it may end up being an issue.
> 
> Thanks for reporting this. I also saw this come up at least one other place:
> 
> https://twitter.com/bendodson/status/712208662933200896 <https://twitter.com/bendodson/status/712208662933200896>
> 
> I wonder if it's worth making #selector(vc.cancel()) work. What do you think, Doug?

Very strong +1; I consider it a bug that we didn't have this already. It was reported as SR-1016 <https://bugs.swift.org/browse/SR-1016>.

Jordan
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