在Xcode8 beta6中，以下代碼將引發警告：'is'test始終為true。但它不會打印通過。    struct TestStruct {    }    //warning: 'is' test is always true    if TestStruct() is AnyObject {        print("pass")    }以下代碼將引發警告：從'T'到'AnyObject'的條件轉換始終成功public static func register<T>(_ protocolType: T.Type, observer: T) {    //Warning: Conditional cast from 'T' to 'AnyObject' always succeeds    guard let object = observer as? AnyObject else {        fatalError("expecting reference type but found value type: \(observer)")    }    //...}