<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 Dec 9, 2015, at 6:30 PM, Joe Groff <<a href="mailto:jgroff@apple.com" class="">jgroff@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: 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="Apple-interchange-newline">On Dec 9, 2015, at 3:20 PM, Amir Michail <<a href="mailto:a.michail@me.com" class="">a.michail@me.com</a>> wrote:<br class=""><br class=""><br class=""><blockquote type="cite" class="">On Dec 9, 2015, at 12:13 PM, Joe Groff <<a href="mailto:jgroff@apple.com" class="">jgroff@apple.com</a>> wrote:<br class=""><br class=""><br class=""><blockquote type="cite" class="">On Dec 9, 2015, at 6:31 AM, Amir Michail via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class="">The following should result in a compile error:<br class=""><br class="">var x:Int? = 5<br class="">var y:Int?<br class=""><br class="">y = x! // compiler error, unwrapping is redundant<br class=""><br class="">The unnecessary unwrapping gives the wrong impression about the type of y — namely that it is Int.<br class=""></blockquote><br class="">The compiler doesn't know this. You gave x type 'Int?', not 'Int’.<br class=""></blockquote><br class="">It knows this because x! has type Int and y has type Int?. So the unwrapping is unnecessary prior to the assignment to y. You should have just written “y = x”.<br class=""></blockquote><br style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: 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: 14px; font-style: normal; font-variant: 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="">Ah, I see what you're saying. This seems like a reasonable warning to add to the compiler; I don't think it requires a formal language change. Got time to file a bug requesting this?</span><br style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: 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=""></div></blockquote><div><br class=""></div><div>Done. It’s SR-167.</div><br class=""><blockquote type="cite" class=""><div class=""><br style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: 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: 14px; font-style: normal; font-variant: 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="">-Joe</span></div></blockquote></div><br class=""></body></html>