If you create a struct and have a property that is of the same type, e.g:

struct Node {
    var parent: Node?
    init() { }
}

You get this error:

value type 'Node' cannot have a stored property that recursively contains it

There are a few ways to work around this. One is to use a "box" class:

class Box<T> {
    var value: T
    init(value: T) {
        self.value = value
    }
}

And change your Node struct to:

struct Node {
    var parent: Box<Node>?
    init() { }
}

Alternatively, wrap it with an array:

struct Node {
    var parent = [Node]()
    init() { }
}

But when you see this error, it's also good to reflect on whether you are building your data structure correctly. in this example our struct is called Node, naturally nodes may refer to their parent. But since structs are value types, we are always copying the parent. If we build a tree of nodes, this copying behavior is not what we want. The simpler and probably more correct answer here is to just Node to be a class instead:

class Node {
    var parent: Node?
    init() { }
}

This will remove the error and more importantly, provide the correct semantics.

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