<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=""><br class=""><div><blockquote type="cite" class=""><div class="">On Aug 17, 2016, at 11:37 AM, Mark Lacey via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Aug 17, 2016, at 11:28 AM, Russ Bishop via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">I wanted to gauge the interest in supporting explicit struct layout and alignment.</div><div class=""><br class=""></div><div class="">The general idea would be to support attributes to create packed structs and set alignment. It will be critical for certain kinds of interop and systems programming in pure Swift. I don’t know about you but I want to write a kernel module in Swift someday :) I’m bringing it up because it probably affects ABI stability and resilience and so meets the requirements for Swift 4 phase 1.</div></div></div></blockquote><div class=""><br class=""></div>Explicit layout matters for the ABI once the feature exists, but it seems purely additive, i.e. out of scope for Swift 4 phase 1. You can ship without any explicit layout support and add it later without impacting code that ships before the feature exists.</div></div></div></blockquote><br class=""></div><div>Agreed. This is something that we’d like Swift to support someday, but it isn’t on the critical path, and it would be a distraction to dive deep on it right now.</div><div><br class=""></div><div>-Chris</div><br class=""></body></html>