swift - 参数类型 'Error'与预期的Swift.Error类型不一致

Question

为什么传递错误给我Argument type 'Error' does not conform to expected type 'Swift.Error'？

enum AltError: Error {
    case error(Error), initializesWereNil
}


enum ErrorAlt<Preferred, Error> {
    
    case preferred(Preferred)
    case error(AltError)
    
    init?(_ preferred: Preferred?, _ err: Error?) {
        if let preferred = preferred {
            self = .preferred(preferred)
        } else if let passedError = err {
            self = .error(.error(passedError))
        } else {
            self = .error(.initializesWereNil)
        }
    }
}

Answer 1

从Error定义中删除通用类型ErrorAlt:

enum ErrorAlt<Preferred> {
    //...
}