SE-0231 — Optional iteration

[endofunk]

@Ben_Cohen

This is not accurate, at least for the problem I outlined. The error-prone solution of ?? [] was an entirely library-level solution, and the problem was not specific to operators. It can happen with methods as well.

Without trying to upset this apple cart. Let's simply review the code sample you provided:

for i in maybeHugeRange?.reversed() ?? [] { // doom occurs here
  print(i) // your app will jetsam without ever reaching here
  break
}

...and consider an alternative method like Rust's unwrap_or. I'll use the simple code sample I provide earlier:

extension Optional {
  func ifSome(orElse: Wrapped) -> Wrapped {
    switch self {
    case .some(let wrapped): return wrapped
    case .none: return orElse
    }
  }
}

Trying to do this kind of this isn't possible re "Left side of nil coalescing operator '??' has non-optional type '[Int]', so the right side is never used"

for i in maybeHugeRange.ifSome(orElse: 0..<0).reversed() ?? [] {
  print(i) // your app will jetsam without ever reaching here
  break
}

So maybe I'm missing the obvious here... how exactly does the method end up with the same issue.