<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="">I'm also in favor of this proposal.<div class=""><br class=""></div><div class="">I'd like to add we would still need a way to define a specific warning message. And sometimes it would make sense to define it for a type. I'm thinking of ReactiveCocoa, where every method returning a Signal as the same @warn_unused_result("did you forget to call 'observe'"). It would be nice to declare this message on the Signal type, and avoid repetition.</div><div class=""><br class=""></div><div class=""><div class="">
<div class="">Pierre</div>
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<br class=""><div><blockquote type="cite" class=""><div class="">Le 18 déc. 2015 à 10:32, Jens Persson via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> a écrit :</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="word-wrap:break-word" class="">strong +1 from me. @warn_unused_result is almost always the right answer in the standard library, and the few cases where it isn’t are very easy to notice (when the call has side-effects and the return value is incidental).<br class=""><div class=""><br class=""></div><div class="">
-Dave</div></div></blockquote><div class=""><br class=""></div><div class="">I'm also in favour of this proposal.</div><div class=""><br class=""></div><div class="">Some days ago, in the swift-dev list ( <a href="https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20151214/000385.html" class="">https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20151214/000385.html</a> ) I was advised by Chris Lattner to bring a related issue into this discussion:</div><div class=""><br class=""></div><div class="">It's about the lack of a warning for simple statements that are unused and thus meaningless (so most probably unintentional). To demonstrate what I mean, here's a short example that currently compiles without any warnings:</div><div class=""><br class=""></div><div class=""><div class="">func thisFuncHasNoWarnings(a: Int) {</div><div class=""> a</div><div class=""> "b"</div><div class=""> "c" as Character</div><div class=""> 1.0</div><div class=""> [2.0, 3.0]</div><div class=""> ["four", 5, 6.7] as [Any]</div><div class=""> "Is this"; a; "problem?"</div><div class="">}</div></div><div class=""><br class=""></div><div class="">I think it might be reasonable to expect a warning on every single line of that function, no?</div><div class="">/Jens</div><div class=""><br class=""></div></div>
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