duplicates:

• SR-704 EXC_BAD_ACCESS on returning nil from a failable initializer of NSObject subclass

Issue Description:

Let me just give a speedy example (you can do it in a playground):

import Cocoa

public extension NSDate {
    public convenience init?(fail: Bool) {
        return nil
    }
}

let date = NSDate(fail: true)

Expectation: date is nil
Result: Program crashes with EXC_BAD_ACCESS

When you do this on a pure Swift class like the following, everything works:

public class X {
}

extension X {
    public convenience init?(fail: Bool) {
        return nil
    }
}

let x = X(fail: true)