Swift 2.2 - 代码崩溃，除非我关闭优化（-Onone）

Question

这是在XCode 7.3上。

如果我使用优化标记-O构建代码，它将会崩溃。它工作正常，没有优化（标志-Onone）。不过，我希望通过优化来构建我的代码。

它是Swift编译器的bug吗？

这是代码。

import Foundation 

extension Dictionary where Key: StringLiteralConvertible, Value: AnyObject { 
    func multipartFormParams(preFix preFix: String = "") -> [String: AnyObject] { 
    var params: [String: AnyObject] = [:] 
    for (key, value) in self { 
     let subKey = preFix != "" ? "\(preFix)[\(key)]" : String(key) 
     if let value = value as? [String: AnyObject] { 
     // params += value.multipartFormParams(preFix: subKey) // this is my original code, however remove the operation extension += to focus on the bug. 
     value.multipartFormParams(preFix: subKey) // It crash here. 
     } else { 
     params[subKey] = value 
     } 
    } 
    return params 
    } 
} 

let parameters: [String: AnyObject] = [ 
    "user": [ 
    "first_name": "first", 
    "last_name": "last" 
    ] 
] 

parameters.multipartFormParams() 

Answer 1

一段时间后，我发现，这是关系到这个错误：https://bugs.swift.org/browse/SR-1114，改变for (key, value) in self {到forEach { key, value in解决了这个问题。

完整的工作版本：

import Foundation 

extension Dictionary where Key: StringLiteralConvertible, Value: AnyObject { 
    func multipartFormParams(preFix preFix: String = "") -> [String: AnyObject] { 
    var params: [String: AnyObject] = [:] 
    forEach { key, value in 
     let subKey = preFix != "" ? "\(preFix)[\(key)]" : String(key) 
     if let value = value as? [String: AnyObject] { 
     // params += value.multipartFormParams(preFix: subKey) // this is my original code, however remove the operation extension += to focus on the bug. 
     value.multipartFormParams(preFix: subKey) // It crash here. 
     } else { 
     params[subKey] = value 
     } 
    } 
    return params 
    } 
} 

let parameters: [String: AnyObject] = [ 
    "user": [ 
    "first_name": "first", 
    "last_name": "last" 
    ] 
] 

parameters.multipartFormParams()