[swift-evolution] @noescape and nil

[Daniel Duan]

Wouldn't this work in Swift 3 though?

func testFunc(times: Int,  fn: (@noescape (Int)->Void)? = nil) { … }

Sent from my iPad

> On Apr 26, 2016, at 11:26 AM, Chris Lattner via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 
>> On Apr 26, 2016, at 12:15 AM, Aleksandar Petrovic via swift-evolution <swift-evolution at swift.org> wrote:
>> 
>> Hi Swift community, I have a question.
>> 
>> This is a valid Swift code:
>> 
>> func testFunc(times: Int, fn: ((Int)->Void)? = nil) {
>> 	guard let f = fn else { return }
>> 	for i in 1 ..< times {
>> 		f(i)
>> 	}
>> }
>> 
>> And this is not:
>> 
>> func testFunc(times: Int, @noescape fn: ((Int)->Void)? = nil) {
>> 	guard let f = fn else { return }
>> 	for i in 1 ..< times {
>> 		f(i)
>> 	}
>> }
>> 
>> I can't think of any hard reason why the @noescape parameter of the function can't be nullable (and, with default value, be optional), but maybe I'm missing something. Is there any plan to correct this in 3.0?
> 
> There are two ways to fix this: a horrible hack that special cases optionals, or the more principled solution that treats optional as the underlying enum type that it is, and making @noescape propagate through to the members of the .some case.
> 
> You can probably guess this, but I’d prefer to discuss fixing the full generality of the problem, not providing a special case in the compiler for this.
> 
> -Chris
> 
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