<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hello,<div class=""><br class=""></div><div class="">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:</div><div class=""><br class=""></div><div class=""><font face="Menlo" class="">class MyButton: UIButton {</font></div><font face="Menlo" class=""><span class="Apple-tab-span" style="white-space:pre"> </span>fileprivate var imageRect: CGRect = .zero<br class=""></font><div class=""><font face="Menlo" class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>fileprivate var titleRect: CGRect = .zero</font></div><div class=""><font face="Menlo" class=""><br class=""></font></div><div class=""><font face="Menlo" class=""> func updateRects() {</font></div><div class=""><font face="Menlo" class=""> if imageBeforeTitle {</font></div><div class=""><font face="Menlo" class=""> layoutHorizontally(leftRect: &imageRect, rightRect: &titleRect)</font></div><div class=""><font face="Menlo" class=""> } else {</font></div><div class=""><font face="Menlo" class=""> layoutHorizontally(leftRect: &titleRect, rightRect: &imageRect)</font></div><div class=""><font face="Menlo" class=""> }</font></div><div class=""><font face="Menlo" class=""> }</font></div><div class=""><font face="Menlo" class=""><br class=""></font></div><div class=""><font face="Menlo" class=""> func layoutHorizontally(leftRect: inout CGRect, rightRect: inout CGRect) {</font></div><div class=""><font face="Menlo" class=""> leftRect.origin.x = padding</font></div><div class=""><font face="Menlo" class=""> rightRect.origin.x = leftRect.maxX + spacing</font></div><div class=""><font face="Menlo" class=""> }</font></div><div class=""><font face="Menlo" class="">}</font></div><div class=""><br class=""></div><div class="">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 <a href="http://bugs.swift.org" class="">bugs.swift.org</a> or if I’m missing something?</div><div class=""><br class=""></div><div class="">David.</div></body></html>