[swift-evolution] Immediately-called closures should be considered @noescape

[Al Skipp]

> On 15 Dec 2015, at 23:16, Brent Royal-Gordon via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Here’s a little annoyance I ran across just now:
> 
>            let sub: CKSubscription = {
>                if let ID = self.ID {
>                    return CKSubscription(recordType: typeName, predicate: predicate, subscriptionID: ID, options: allMutations)
>                }
>                else {
>                    return CKSubscription(recordType: typeName, predicate: predicate, options: allMutations)
>                }
>            }()
> 
> This closure obviously never leaves the enclosing function, but Swift doesn’t treat it as if it had been passed to a @noescape function, so I have to say “self.ID” instead of “ID” in the condition. That’s a bit irritating, and I’d like to see it improved.

Would the following be acceptable, or too dense?

let sub = ID.map { id in
  CKSubscription(recordType: typeName, predicate: predicate, subscriptionID: id, options: allMutations)
} ?? CKSubscription(recordType: typeName, predicate: predicate, options: allMutations)

Either way, I agree that immediately called closures should be implicitly @noescape.