Swift compiler segmentation fault when building

Question

Adding a (convenient) computed height property to UIView in my UIViewExtension.swift file is causing the Swift compiler to segfault...

Answer 1

This error happens also if you accidentally declare a variable with a type matching its name:

    var sectionGroup: sectionGroup? { ... }

Answer 2

Xcode 8.2.

Adding @nonobjc protocol implementation into extension causing segmentation faults. Move @nonobjc protocol implementation into class implementation.

Answer 3

Seems like the Swift 2 compiler might not have been quite ready for prime-time! In case this helps anyone, I was getting a segmentation fault: 11 due to a mismatch with the variable type in a closure header, specifically in a Parse method, PFQuery.query.findObjectsInBackgroundWithBlock.

You can see the issue in more detail here: https://github.com/ParsePlatform/Parse-SDK-iOS-OSX/issues/280

Answer 4

In my case the culprit was accidentally overloading a function expecting an array argument with one with a variadic argument:

public required init(_ args: Node...) {
}

When the superclass had it defined as an array:

public required init(_ args: [Node]) {
}

Answer 5

This typically happens when the compiler does not have enough information (despite what you think) to guarantee/determine the state of a statement or a variable within a statement.

For example, imagine you have a dictionary of type [String: String] which you populate with city names as keys and a comma separated list of corresponding zip codes/post codes.

Imagine that somewhere in your code you want to update the list of corresponding codes:

myDict[town] += newZipCode + ","

In this case, the compiler will respond with segmentation fault as town might not be in the dictionary and therefore it cannot guarantee that the above statement will have a valid value.

To resolve this, you should store the current state of myDict[town] in a separate variable allowing you to handle the case of key not in dict and then update the value for the given key:

myDict[town] = guaranteedValue + "," newZipCode + ","

Unfortunately, it is not always straightforward to determine the root cause so I hope this simple example helps.

Answer 6

I had this error because I was doing this :

if(currentMeal?.State == .Deleted){

}

instead of

if(currentMeal!.State == .Deleted){

}

so I think optional not unwrapped in if condition can cause this error