Open Radar

 
Summary:
NSWindowController's init method calls [self initWithWindow:].  In particular, it calls an initializer on self.  This means that -[NSWindowController init] is not a designated initializer: designated initializers are exactly those that call an initializer on super.  However, -[NSWindowController init] is NOT marked as a convenience, so it is understood by the compiler to be designated.

This results in the possibility of writing an NSWindowController subclass that with a new designated initializer that compiles (but shouldn't) and traps when instantiated.

Steps to Reproduce:
1.  Open the attached project.

Alternatively.

Alt.1.1:  Create a new project using the Cocoa Application template (with "Use Storyboard", "Create Document-Based Application", and "Use Core Data" all unchecked).
Alt.1.2:  Into AppDelegate.swift, paste the following class (outside of the definition of the AppDelegate class).

class WindowController: NSWindowController {
    init(arg: Int) {
        super.init()
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

Alt.1.3.  Into AppDelegate.applicationDidFinishLaunching(_:), paste the following line:

let wc = WindowController(arg: 0)

2.  Attempt to run the app.

Expected Results:
1.  The app should fail to compile. 
2.  In Xcode, the line <<super.init()>> in WindowController.init(arg:) should be highlighted red with the error message <<Must call a designated initializer of the superclass 'NSWindowController'>>.

Actual Results:
1.  The app compiles.
2.  When the app runs, it traps inside WindowController's implicitly generated override of init(window:).  Here is the header in the disassembly for the implicitly generated method.

NSWindowControllerInitIsDesignatedBug`NSWindowControllerInitIsDesignatedBug.WindowController.init (NSWindowControllerInitIsDesignatedBug.WindowController.Type)(window : Swift.Optional<ObjectiveC.NSWindow>) -> NSWindowControllerInitIsDesignatedBug.WindowController at AppDelegate.swift:

Version:
Latest 6.2 beta.

Notes:
The "workaround" is to call super.init(window:) (or super.init(coder:)) from the subclass' DI.  This is actually the right thing to do.  The compiler should enforce this.  It will enforce it when -[NSWindowController init] is properly tagged as convenience.

Configuration: