<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 Nov 27, 2016, at 4:32 PM, David Sweeris via swift-dev <<a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On Nov 26, 2016, at 5:25 PM, Robert Widmann via swift-dev <<a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div dir="auto" class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div dir="auto" class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hello all,<div class=""><br class=""></div><div class="">I’ve seen and been a part of a number of conversations recently where talk of planning for “resilient enums”, or even just authors that ship frameworks that will eventually offer a binary option that export enum-based APIs. The consensus seems to be that the only safe way to deal with this situation is to<span class="Apple-converted-space"> </span><i class="">always</i> cover a `switch` statement with a default, regardless of whether the totality checker thinks you’ve covered all cases. Currently, the compiler warns when this is the case, as in stdlib</div><div class=""><br class=""></div><div class=""><div class="" style="margin: 0px; font-size: 11px; line-height: normal;"><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;">extension ProcessTerminationStatus {</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> var isSwiftTrap: Bool {</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> switch self {</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> case .exit(_):</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> return false</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> case .signal(let signal):</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> return CInt(signal) == SIGILL || CInt(signal) == SIGTRAP</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> default:</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal; color: rgb(0, 132, 0);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> <span class="Apple-converted-space"> </span></span><span class="" style="font-variant-ligatures: no-common-ligatures;">// This default case is needed for standard library builds where</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal; color: rgb(0, 132, 0);"><span class="" style="font-variant-ligatures: no-common-ligatures;"> <span class="Apple-converted-space"> </span></span><span class="" style="font-variant-ligatures: no-common-ligatures;">// resilience is enabled</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> return false</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> }</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"> }</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;">}</span></div><div class="" style="font-family: Menlo; margin: 0px; line-height: normal;"><span class="" style="font-variant-ligatures: no-common-ligatures;"><br class=""></span></div><div class="" style="margin: 0px; line-height: normal;">I think this warning doesn’t actually serve a purpose and I’d like to remove it, or at the very least curb it. Currently, I see three paths forward:</div><div class="" style="margin: 0px; line-height: normal;"><br class=""></div><div class="" style="margin: 0px; line-height: normal;">1) Do nothing.</div><div class="" style="margin: 0px; line-height: normal;">2) Completely remove the diagnostic</div><div class="" style="margin: 0px; line-height: normal;">3) Only emit the diagnostic when the case-tree is switching over enum(s) declared inside the current module.</div></div></div></div></div></div></div></blockquote><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Has the “resilient enum” thing been finalized, or is this kind of code just a preventative measure?</div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Also, if “resilience” is a compiler flag, there's a fourth option: Disable the warning on builds that have “resilience” enabled.</div></div></blockquote><div><br class=""></div><div>The warning is already gone (and the default cause is required) when the standard library and overlays are built with resilience enabled. The issue is that resilience is off by default.</div><div><br class=""></div><div>I agree the warning is annoying; we should figure out something.</div><div><br class=""></div><blockquote type="cite" class=""><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">- Dave Sweeris</div><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">_______________________________________________</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">swift-dev mailing list</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="mailto:swift-dev@swift.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">swift-dev@swift.org</a><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><a href="https://lists.swift.org/mailman/listinfo/swift-dev" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://lists.swift.org/mailman/listinfo/swift-dev</a></div></blockquote></div><br class=""></body></html>