Open Radar

 
This array cast causes a bad instruction error at runtime:

protocol ItemProtocol {
    var duration: Float {get}
}

class TestItem: ItemProtocol {
    let duration: Float = 42
}

let item = TestItem()
let testArray = [item] // Type is [TestItem]
let convertedArray = testArray as [ItemProtocol] // Error: bad instruction

It's not shown here, but in the actual use context from which I created this minimal example, the console also shows "fatal error: array element cannot be bridged to Objective-C". But there's no Objective-C in sight.

This might be related to the issue reported at https://devforums.apple.com/message/1069470#1069470, but in this case, everything is 100% Swift. There should be no bridging.

This is in Xcode 6.2 beta 3.