<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=""><div class="">We’ll warn if that kind of cast is a tautology, right? That leaves only the dynamic casts, which can’t be assumed exhaustive.</div><div class=""><br class=""></div><div class="">~Robert Widmann</div><br class=""><div><blockquote type="cite" class=""><div class="">On May 9, 2017, at 2:13 PM, Jordan Rose <<a href="mailto:jordan_rose@apple.com" class="">jordan_rose@apple.com</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="" applecontenteditable="true"><div class="">It's neither a variable binding nor an expression pattern, right? It has to be compared against the original type to know whether it's exhaustive or not. (Consider "let error as NSError" in a catch clause, which should be considered exhaustive.)</div><div class=""><br class=""></div><div class="">Jordan</div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 9, 2017, at 11:12, Robert Widmann <<a href="mailto:devteam.codafi@gmail.com" class="">devteam.codafi@gmail.com</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="">It’s mine, yep. It looks like it’s classifying the cast in the first pattern as a variable binding instead of an expression pattern. I’ll push a fix later.</div><div class=""><br class=""></div><div class="">Thanks!</div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 9, 2017, at 1:52 PM, Jordan Rose <<a href="mailto:jordan_rose@apple.com" class="">jordan_rose@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=us-ascii" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="" applecontenteditable="true"><div class="">That looks like a bug to me, since of course the first pattern won't always match. I suspect this is Robert's work on trying to make the exhaustive checks better, <a href="https://github.com/apple/swift/pull/8908" class="">https://github.com/apple/swift/pull/8908</a>. Thanks for catching this!</div><div class=""><br class=""></div><div class="">Jordan</div><div class=""><br class=""></div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 9, 2017, at 07:09, Pushkar N Kulkarni 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=""><font face="Verdana,Arial,Helvetica,sans-serif" size="2" class=""><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class="">Hi there, </div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><br class=""></div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class="">I see a new warning message for switch statements on enums, like this one: </div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><br class=""></div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">enum Test {</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> case one(Any)</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> case two</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo; min-height: 16px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">let x: Test = .one("One")</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">switch x {</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> case .one(let s as String): print(s)</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> case .one: break</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> case .two: break</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div></div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><b class="">enum.swift:9:10: </b></span><span style="font-variant-ligatures: no-common-ligatures;" class=""><font color="#d53bd3" class=""><b class="">warning: </b></font></span><span style="font-variant-ligatures: no-common-ligatures" class=""><b class="">case is already handled by previous patterns; consider removing it</b></span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> case .one: break </span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div></span></div><div style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class=""><font face="Verdana,Arial,Helvetica,sans-serif" size="2" class=""><font class=""><font class=""><div class="socmaildefaultfont" dir="ltr"><div class="socmaildefaultfont" dir="ltr"><div class="socmaildefaultfont" dir="ltr"><div dir="ltr" style="font-style: normal;" class=""><font class="">I do not see this warning with the 04-24 dev snapshot. </font></div><div dir="ltr" style="font-style: normal;" class=""><font class=""><br class=""></font></div><div dir="ltr" style="font-style: normal;" class=""><font class="">The warning goes away with the use of the wildcard pattern in the second case:</font></div><div dir="ltr" style="font-style: normal;" class=""><font class=""><br class=""></font></div><div dir="ltr" style="font-style: normal;" class=""><font class=""><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">switch x {</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""> case .one(let s as String): print(s)</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""> case .one(_): break</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""> case .two: break</span></div><div style="margin: 0px; font-size: 14px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">}</span></div></font></div><div dir="ltr" style="font-style: normal;" class=""><font class=""><br class=""></font></div><div dir="ltr" style="font-style: normal;" class=""><font class=""><br class=""></font></div><div dir="ltr" style="font-style: normal;" class=""><font class="">I am wondering if this change is intentional, though it does make sense to me. Can someone please point me to the related commit?</font></div><div dir="ltr" style="font-style: normal;" class=""><font face="Sans Serif, Verdana, Arial, Helvetica, sans-serif" style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><br class=""></font></div><div dir="ltr" style="font-style: normal;" class=""><font face="Sans Serif, Verdana, Arial, Helvetica, sans-serif" style="font-family: Verdana, Arial, Helvetica, sans-serif;" class="">Thanks in advance!</font></div><div dir="ltr" style="font-style: normal;" class=""><font face="Sans Serif, Verdana, Arial, Helvetica, sans-serif" style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><br class=""></font></div><div dir="ltr" style="font-style: normal;" class=""><font face="Sans Serif, Verdana, Arial, Helvetica, sans-serif" style="font-family: Verdana, Arial, Helvetica, sans-serif;" class="">Pushkar N Kulkarni,</font></div>
<div dir="ltr" style="font-family: Verdana, Arial, Helvetica, sans-serif; font-style: normal;" class=""><font face="Sans Serif, Verdana, Arial, Helvetica, sans-serif" class="">IBM Runtimes</font></div><div dir="ltr" style="font-family: Verdana, Arial, Helvetica, sans-serif; font-style: normal;" class=""><font face="Sans Serif, Verdana, Arial, Helvetica, sans-serif" class=""><br class=""></font></div><div dir="ltr" style="font-family: Verdana, Arial, Helvetica, sans-serif;" class=""><font face="serif, Times New Roman, Times, serif" class=""><i class="">Simplicity is prerequisite for reliability - Edsger W. Dijkstra</i></font></div>
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