Noncopyable Generics in Swift: A Code Walkthrough

This is superb.

It could also be the basis for a blog post (probably around the time of Swift 6's release, or whenever the relevant features mainlined). I realise non-copyable types are intended to be a niche feature, but I think the audience for this kind of introductory howto is much bigger as it includes people that are simply curious.

Maybe, right? If the compiler determines that the caller has no need for the value after Box's init, it can pass it directly, no?

Though this requires that the let variable be invalidatable, right? So it couldn't be e.g. a stored property (except if you're consuming it in deinit or equivalent?)?

Missing where Wrapped == Copyable?

Is it an intrinsic requirement that the compiler implement that synthesised deinit as a recursive algorithm rather than an iterative one?

Or perhaps more to the point, as depth-first rather than breadth-first?

Just out of tangential curiosity.

I wouldn't expect it to special-case a singly-linked list or anything, but it does seem plausible that it could recognise cases where back-references are impossible, and delete as it goes.

Yeah, while it makes sense as written given the current rules, I guarantee I'm going to first write the following instead, every single time:

mutating func pop() -> Element? {
    if let node = head?.move() {
        head =
        return node.element
    } else {
        return nil

It'll be great when that's one day supported as well, re. the partial consumption proposal etc.

[Tangentially] Nah, because with optional chaining situations for…in loops are often worse. And I say that even though I'm increasingly growing to hate the use of trailing closures to mimic basic blocks (given the compiler's inability to reason through the control flow, and thus how it breaks even the most rudimentary features like initialisation of lets).