Open Radar

 
Summary:
Consider the following code:

func noexcept<T>(@autoclosure call: () throws -> T) -> T? {
    do {
        return try call()
    } catch {
        return nil
    }
}

enum Error: ErrorType {
    case SomeError
}

func throwException() throws -> Int {
    throw Error.SomeError
}

func acceptClosure(closure: () -> Void) {
    closure()
}

func test() {
    acceptClosure {
        let _ = noexcept(try throwException())
    }
}

test()


It fails to compile. Error shown is "Invalid conversion from throwing function of type '() throws -> Void' to non-throwing function type '() -> Void'". It's on the line where 'acceptClosure' is called. For some reason compiler thinks that the closure that is passed to 'acceptClosure' throws, but it really can't throw since it only calls non-throwing function 'noexcept'.

If I remove @autoclosure from definition of 'noexcept' and replace 'noexcept(try throwException())' with 'noexcept { try throwException() }', it compiles fine. So autoclosure variant of the function should also compile fine.

Steps to Reproduce:
1. Install Xcode 7.0b6 (7A192o).
2. Create a playground for iOS, paste my code snippet in playground.
3. Code fails to compile with described message.

Expected Results:
Code should compile fine.

Actual Results:
Code fails to compile.

Version:
Xcode 7.0b6 (7A192o), OS X 10.10.5.

Notes:


Configuration:
Swift 2.0, Xcode 7.0b6 (7A192o), OS X 10.10.5, building for iOS 9.0.

Attachments: