Command failed due to signal: Abort trap: 6

My case, Swift 5.1, Xcode 10.3 (10G8)

Code was crashing Swift when a nested function was using the argument of an outer function as a default parameter.

e.g.

func foo(duration: TimeInterval) {
func bar(duration: TimeInterval = duration) {
}
}

I hope this helps.

For me below statement cause an error.

let dict = mainDict as [String:String]


Fix the issue by `force unwraps`

let dict = mainDict as! [String:String]

**There is nothing related to the compiler. It is just type casting issue, Apple should give proper description instead of the giving compiler error**

I was able to resolve it by making a change to the bridging header. In my case adding a line break was sufficient. Very strange bug.

This issue is still present in Xcode 10.2.1. After **cleaning the build folder**, the error went away.

For me it was MD5.swift issue

What you have to do is search in your project for file name "MD5.swift" even in the pods

and replace all the content with this file here

[To see links please register here]

I fixed it by going to Xcode -> Preferences -> Locations -> Set `Relative` option to Derived Data.

[![Setting Derived Data][1]][1]


[1]:

I got this error when attempting to run tests.
To solve it, I put this script into Terminal:

`rm -rf ~/Library/Developer/Xcode/DerivedData`

Deleting derived data resolved the issue

In Xcode 9.3, I have re-installed the specific pod, in which warnings appeared and cleared derived data again n again. It worked for me :)

I didn't try other solutions.
I got this problem for this setup:

func speacialAdd(_ num1: Int, to num2: Int){
func specialMultiply(_ digit1: Int, with digit2: Int = num2){ // SOURCE OF PROBLEM
print(digit2)
print(digit1)
}

specialMultiply(5)
}

class ViewController: UIViewController {

override func viewDidLoad() {
super.viewDidLoad()
print(speacialAdd(5, to: 6))
}
}

This line is the source of problem. Defaulting it to a argument seems to not work for a nested function

func specialMultiply(_ digit1: Int, with digit2: Int = num2) // ERROR

Solutions are:

func specialMultiply(_ digit1: Int, with digit2: Int) // OK
func specialMultiply(_ digit1: Int, with digit2: Int = 6) // OK

-----

FWIW I actually first wrote this in playground and got a different error:

> Playground execution failed:
>
> error: Couldn't lookup symbols:
> __T013__lldb_expr_111speacialAddySi_Si2totF4num2L_Sifau

Make sure you don't implement a private protocol into class extension. Most of the time would be quite strange to have a private protocol, but not necessary, depending on what you wish to encapsulate.

Something like, in the same file:

class C: ... {
}

extension C: P {
}

private protocol P: class {
}

Do this an you'll surely get `Command failed due to signal: Abort trap: 6`

Instead remove the `private` modifier from the protocol and the error is fixed.