Swift compiler Error "failed with exit code 254"

Question

When I update Xcode 6 from Beta 4 to the Beta 6, I have this (new) compiler error and I don't know how to fix it.

<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-Beta6.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 254

The concerned lines are these

let reuseId = "test"

    var anView = mapView.dequeueReusableAnnotationViewWithIdentifier(reuseId)
    if anView == nil{...}

Thanks.

Just go to [bugreport.apple.com](https://bugreport.apple.com/), you'll figure out what to do next. — akashivskyy, Aug 31 '14 at 13:33
Have you cleaned your project and cleared out your derived data? (Organizer->Projects->the project in question->Derived Data->Delete) I had a few compiler crashes after upgrading to 6 that seemed to have been caused by old derived data. — Matt Gibson, Aug 31 '14 at 14:18

score 2 · Answer 1 · answered Sep 05 '14 at 01:50

I'm having a similar issue when archiving in beta 6 & 7. I finally tracked it down to something to do with the Swift Compiler - Code Generation - Optimization Level - Fastest[-O]. If set the optimization level to none everything works fine, but when set to anything else xcode throws a 254 error.

schnabler · Answer 2 · 2014-09-02T00:27:27.667

I'd love to simply write this as a comment to your question, but I'm lacking reputation to do so.

I have a similar problem, and I have tracked it down to CoreLocation in combination with MapKit (from your other questions, I think you are building a location based app as well) by basically copying and pasting my old project line by line into a new one.

Once I use CoreLocation and MapKit combined (in two different controllers), this error comes up.

import UIKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    }
}

and

import UIKit
import MapKit

class SecondViewController: UIViewController, MKMapViewDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    }
}

with both MapKit and CoreLocation added, I get

<unknown>:0: error: unable to execute command: Segmentation fault: 11
<unknown>:0: error: merge-module command failed due to signal (use -v to see invocation)
Command /Applications/Xcode6-Beta6.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swiftc failed with exit code 254

or

Use of undeclared type 'CLLocationManagerDelegate'

depending on if I also add MapKit to ViewController (without adding MKMapViewDelegate). I also makes a difference if I add MKMapViewDelegate to SecondViewController before adding an import MapKit statement to ViewController - just so you have an idea of how weird this behavior is.

I know, it's a long shot, but maybe you can gain some insight here.

EDIT: And oh - I'm quite sure this is simply an Xcode bug. They call it beta for a reason.

A really long one yeah ! :) But @schnabler, I think it is a simply Xcode bug too, and I have no idea to do with this strange behaviour... Try to Ask your question but I think the response will be the same ! — PMIW, Sep 03 '14 at 06:22

score 0 · Accepted Answer · answered Sep 04 '14 at 09:20

0

The bug was solved in Beta 7 available online today.

answered Sep 04 '14 at 09:20

PMIW

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Swift compiler Error "failed with exit code 254"

3 Answers3