Open Radar

 
This is a weird one but I finally found the reproduction steps. Just check out the example below.

Steps to Reproduce:
// Playground - noun: a place where people can play

import Cocoa

class GeneralThing<S> {
	var stuff: S?

	func doIt() {
		if let s = stuff {
			doWithStuff(s)
		}
	}

	func doWithStuff(stuff: S) -> S {
		return stuff
	}
}

class SpecificThing<T>: GeneralThing<Int> {
	override func doWithStuff(stuff: Int) -> Int {
		println("\(stuff + 1)")
		return stuff + 1
	}
}

let t = SpecificThing<Float>()
t.stuff = 1
t.doIt()


Expected Results:
Should print "2" and return 2.

Actual Results:
In a playground it seems to (usually) crash. Though not always. The `stuff` argument passed to `SpecificThing.doWithStuff` seems to be garbage.