Open Radar

 
Summary:
I’m trying to write the &&& operator I describe here: http://intersections.tumblr.com/post/111240204394/the-sum-is-more-than-the-hole-of-its-parts-while

I want to use @autoclosure so it’ll act like Swift’s && over Bool, but the natural implementation using Optional.map() is impossible, because Optional.map() doesn’t mark its function as @noescape, so Swift doesn’t know that the function parameter can be passed in without allowing it to escape.


Steps to Reproduce:
1. Write this:
infix operator &&& { associativity left precedence 120 }
public func &&& <T, U> (left: T?, @autoclosure right: () -> U?) -> (T, U)? {
	return left.map { x in right().map { y in (x, y) } } ?? nil
}


Expected Results:
I expected to be able to call right in the left.map closure.


Actual Results:
“Closure use of @noescape parameter 'right' may allow it to escape”


Regression:
Using this instead of map works just fine:

extension Optional {
	func fmap<U>(@noescape f: T -> U) -> U? {
		switch self {
		case let Some(x):
			return f(x)
		case None:
			return nil
		}
	}
}


Notes:
I really loathe how Swift 1.2 ties @autoclosure to @noescape. It’s an exercise in frustration every time I try to use @autoclosure, now, and it had previously been one of my favourite bits of the language.