Xcode swift失败，退出代码为254 [英] Xcode swift failed with exit code 254

问题描述

我的代码中出现此编译错误，我无法弄清楚原因：

I am getting this compiler error in my code and I can't figure out why:

<unknown>:0: error: unable to execute command: Segmentation fault: 11
<unknown>:0: error: swift frontend command failed due to signal (use -v to see invocation)
Command /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift failed with exit code 254

错误显示在以下代码段中的某处：

The error is showing up somewhere in the following code segment:

var animalViewToSwap: AnimalView = animalViewMatrix.objectAtRow(0, andColumn: 0) as AnimalView
var currentRow = 0
var currentColumn = 0
var animalToSwapWith = true

var currentLocation = animalViewMatrix.findLocationOfObject(animalView)

currentRow = Int(currentLocation.row) - 1
currentColumn = Int(currentLocation.column) - 1

var rowDisplacement = 0
var columnDisplacement = 0

switch inDirection{

    case "left":
        columnDisplacement = withDistance * -1
        if (Int(animalViewMatrix.columns) > currentColumn + columnDisplacement)&&(currentColumn + columnDisplacement >= 0)&&(animalViewMatrix.objectAtRow(CInt(currentRow), andColumn: CInt(currentColumn + columnDisplacement)) is AnimalView)
        {
            animalToSwapWith = true;
        }
        else { animalToSwapWith = false }

    default:
        println("error")
        animalToSwapWith = false
        break
}

（我有更多非常相似的案例，为了简单起见，我们将它们排除在外 - 这个bug不在其中）

(I have more cases that are very similar and am leaving them out for simplicity - the bug isn't in them)

行中有一个错误： animalToSwapWith = false 如果我将其设置为true并在除变量初始化行之外的所有其余部分进行注释，则错误消失。此外，如果我将所有内容都注释掉但是将animalToSwapWith实例化为false，则会发生错误，即使它实例化为true时也不会发生错误。

One bug is in the line: animalToSwapWith = falseand if I set it to true and comment all the rest out besides the variable initialization lines the error goes away. Also if I comment all of it out but instantiate animalToSwapWith to false the error occurs even though it doesn't when it is instantiated to true.

行中有第二个错误： if（Int（animalViewMatrix.columns）> currentColumn + columnDisplacement）&&（currentColumn + columnDisplacement> = 0）&&（animalViewMatrix.objectAtRow（CInt（currentRow），andColumn：CInt（currentColumn + columnDisplacement））是AnimalView）在这一行中，所有这些方法都在文件的前面调用过使用上述相同类型的变量，因此对方法的了解无关紧要。

There is a second error in the line:if (Int(animalViewMatrix.columns) > currentColumn + columnDisplacement)&&(currentColumn + columnDisplacement >= 0)&&(animalViewMatrix.objectAtRow(CInt(currentRow), andColumn: CInt(currentColumn + columnDisplacement)) is AnimalView) In this line all of these methods have been called earlier in the file with variables of the same types above so knowledge of the methods shouldn't matter.

是否有这两个错误发生的原因或是因为swift和Xcode-6仍在进行beta测试，这是Xcode中的一个错误？另请注意，当一次一个地将两个错误注释掉时，错误消息是相同的。

Is there a reason why these two errors are occurring or is it because swift and Xcode-6 are still in beta testing and it is a bug in Xcode? Also note that when commenting the two errors out from each other one at a time the error message is the same.

推荐答案

这是一个Swift编译器错误，显然是对两个或多个隐式解包的选项进行测试会导致编译器在某些/多个情况下崩溃情况。使用 Apple的Bugreporter 提交此问题，将其标记为rdar：// 17212295的副本。

This is a Swift compiler bug, apparently testing for two or more implicitly unwrapped optionals causes the compiler to crash under some/many circumstances. Use Apple's Bugreporter to file this issue, mark it as duplicate of rdar://17212295.

以下是崩溃时出现同样错误的最小示例：

Here's a minimal example that crashes with the same error:

let a: String!
let b: String!

if a && b {
    println("have both")
}

编译命令行如下并见证同样的崩溃：

Compile on command line as follows and witness the same crash:

$ xcrun swift -v -g crash.swift

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