<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="">As I see it, this is serious bug. In Swift 3.0, parameter labels (or lack of them) are supposed to be a part of the function name. <div class=""><div class=""><span style="font-variant-ligatures: no-common-ligatures" class="">Otherwise, the two `key` definitions would create a name collision and should have been rejected in the first place. This should not happen, because only `key(at:)` should be treated as a method pointer and not `key`. Even the following example:</span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">protocol</span><span style="font-variant-ligatures: no-common-ligatures" class=""> QueryRow {</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> key: </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">Any</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">get</span><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> key(</span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">_</span><span style="font-variant-ligatures: no-common-ligatures" class=""> index: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">UInt</span><span style="font-variant-ligatures: no-common-ligatures" class="">) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">Any</span><span style="font-variant-ligatures: no-common-ligatures" class="">?</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class="">should not create a collision as method pointer now is `key(_:)` and not `key`. I guess the reason this is happening is some attempt at backward compatibility, but this is clearly causing a serious bug. Have you reported it?</span></div></span></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Sep 13, 2016, at 1:13 PM, Jens Alfke via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@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="">One of my co-workers just noticed a problem with the (bridged) API of our Objective-C framework, when used from Swift 3 (but not earlier). We have a class CBLQueryRow that includes the following:<div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>@property (readonly) id key;</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- (nullable id) keyAtIndex: (NSUInteger)index;</div><div class=""><br class=""></div><div class="">In Swift this becomes</div><span class="Apple-tab-span" style="white-space:pre"> </span>open var key: Any { get }<br class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>open func key(at index: UInt) -> Any?<br class=""><div class=""><br class=""></div><div class="">The problem is that any reference to `key` now seems to refer to a pointer to the method, not to the property, leading to compiler diagnostics like the following (where `row` is a CBLQueryRow):</div><div class=""><br class=""></div><div class=""><div class="">TaskListsViewController.swift:95:40: warning: cast from '(UInt) -> Any?' to unrelated type 'String' always fails</div><div class=""> cell.textLabel?.text = row.key as? String</div><div class=""> ~~~~~~~ ^ ~~~~~~</div>That’s a warning not an error, but obviously at runtime the `as?` would always fail and result in nil.</div><div class=""><br class=""></div><div class="">This is rather bad for us, since the `key` property is a crucial part of the API, while the `key()` method that pre-empts it is obscure and little-used.</div><div class=""><br class=""></div><div class="">I can reproduce this in a playground in Xcode 8 like so:</div><div class=""><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">protocol</span><span style="font-variant-ligatures: no-common-ligatures" class=""> QueryRow {</span></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> key: </span><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">Any</span><span style="font-variant-ligatures: no-common-ligatures" class=""> { </span><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">get</span><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">func</span><span style="font-variant-ligatures: no-common-ligatures" class=""> key(at index: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">UInt</span><span style="font-variant-ligatures: no-common-ligatures" class="">) -> </span><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">Any</span><span style="font-variant-ligatures: no-common-ligatures" class="">?</span></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(52, 56, 146);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">var</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> row: </span><span style="font-variant-ligatures: no-common-ligatures" class="">QueryRow</span></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #814100" class="">row</span><span style="font-variant-ligatures: no-common-ligatures;" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #343892" class="">key</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #005493" class="">as</span><span style="font-variant-ligatures: no-common-ligatures;" class="">? </span><span style="font-variant-ligatures: no-common-ligatures" class="">String</span></div></div></blockquote><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span></div></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span></div></div><div class="">In addition to the valid error about `row` being uninitialized, I also get the cast failure.</div><div class=""><br class=""></div><div class="">What’s the best workaround for this?</div><div class=""><br class=""></div><div class="">—Jens</div></div>_______________________________________________<br class="">swift-users mailing list<br class=""><a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a><br class="">https://lists.swift.org/mailman/listinfo/swift-users<br class=""></div></blockquote></div><br class=""></div></div></body></html>