[swift-users] Law of Exclusivity runtime false positive?

David Hart david at hartbit.com
Thu Jul 27 07:04:18 CDT 2017


In Xcode 9 beta 4, Swift 4, I’m getting runtime errors popping up for Simultaneous accesses and I think they may be false negatives. Here’s a stripped down version of my code:

class MyButton: UIButton {
	fileprivate var imageRect: CGRect = .zero
	fileprivate var titleRect: CGRect = .zero

        func updateRects() {
            if imageBeforeTitle {
                layoutHorizontally(leftRect: &imageRect, rightRect: &titleRect)
            } else {
                layoutHorizontally(leftRect: &titleRect, rightRect: &imageRect)

        func layoutHorizontally(leftRect: inout CGRect, rightRect: inout CGRect) {
            leftRect.origin.x = padding
            rightRect.origin.x = leftRect.maxX + spacing

While the layoutHorizontally method has two CGRect inout parameters, never in my code do I pass the same CGRect. Any ideas if this is a bug I should post on bugs.swift.org or if I’m missing something?

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