<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 Apr 25, 2016, at 1:13 PM, Erica Sadun <<a href="mailto:erica@ericasadun.com" class="">erica@ericasadun.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="">With apologies, I do not see near miss checks as a pressing need:</div><div class=""><br class=""></div><div class="">* Quick Help lists of required members (including associated types and inherited members) would be far more valuable to me than "near miss" detection.</div></div></div></blockquote><div><br class=""></div>Understood.</div><div><br class=""><blockquote type="cite" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><br class=""></div><div class="">* I'd like the compiler to check for unsatisfied conformances and emit a list of required conformances including whether they are found and their origin. This would tangentially address the "near miss" case but only for unsatisfied conformances. It would not help when conformances are satisfied.</div></div></blockquote><div><br class=""></div><div>Yes, the experience here is terrible. What the compiler *should* do is give a serious of errors, each of which corresponds to a single requirement and has a Fix-It to stub out the appropriate method/property/etc. </div><br class=""><blockquote type="cite" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">* I believe "near miss" is less important than "intentional override", requiring a signature of intent as in inheritance. </div></div></blockquote><div><br class=""></div><blockquote type="cite" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Here's what you said previously on the topic of default implementation overrides that brought me here:</div><div class=""><div class=""></div><blockquote type="cite" class=""><div class=""><br class=""></div><div class=""><div class="" style="font-family: Palatino-Roman;">This is a commonly-requested feature that I don’t think we need. The TL;DR version is that I feel like specifying the conformance explicitly (my type Foo conforms to protocol P) already expresses intent, and the compiler should help with the rest. I’ve recently been working on providing better warnings for cases where one has tried to implement an optional requirement for a protocol (but got the declaration wrong), and I think we can turn it on for cases where one got a default implementation instead:</div><div class="" style="font-family: Palatino-Roman;"><br class=""></div><div class="" style="font-family: Palatino-Roman;"><span class="Apple-tab-span" style="white-space: pre;"> </span><a href="http://thread.gmane.org/gmane.comp.lang.swift.devel/1799" class="">http://thread.gmane.org/gmane.comp.lang.swift.devel/1799</a></div></div></blockquote></div></div></blockquote><div><br class=""></div><div>My opinion is that the signature of intent is the explicitly-stated conformance to the protocol, but this is not universally agreed upon (even within the core team). It suffices to say that a proposal to add some kind of “implements” keyword won’t come from me :)</div><div><br class=""></div><span class="Apple-tab-span" style="white-space:pre"> </span>- Doug</div><div><br class=""><blockquote type="cite" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><br class=""></div><div class="">-- Erica</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div class="">On Apr 22, 2016, at 4:33 PM, Douglas Gregor 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=""><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="">Hi all,<div class=""><br class=""></div><div class="">A common complaint with protocol conformance checking is that it’s easy to make a little mistake when trying to implement a protocol requirement that has a default implementation. Here is a silly example:</div><div class=""><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class=""><div class=""><font face="Menlo" class="">protocol P { </font></div></div><div class=""><div class=""><font face="Menlo" class=""> func foo(value: Float)</font></div></div><div class=""><div class=""><font face="Menlo" class="">}</font></div></div><div class=""><div class=""><font face="Menlo" class=""><br class=""></font></div></div><div class=""><div class=""><font face="Menlo" class="">extension P {</font></div></div><div class=""><div class=""><font face="Menlo" class=""> func foo(value: Float) { } // default implementation of P.foo(value:)</font></div></div><div class=""><div class=""><font face="Menlo" class="">}</font></div></div><div class=""><div class=""><font face="Menlo" class=""><br class=""></font></div></div><div class=""><div class=""><font face="Menlo" class="">struct S { }</font></div></div><div class=""><div class=""><font face="Menlo" class=""><br class=""></font></div></div><div class=""><div class=""><font face="Menlo" class="">extension S : P {</font></div></div><div class=""><div class=""><font face="Menlo" class=""> func foo(value: Double) { } // intended-but-incorrect attempt to satisfy the requirement P.foo(value:)</font></div></div><div class=""><div class=""><font face="Menlo" class="">}</font></div></div></blockquote><div class=""><br class=""></div><div class="">S satisfies the requirement for P.foo(value:) using the implementation from the protocol extension, although it certainly looks like the user intended to provide a different implementation.</div><div class=""><br class=""></div><div class="">This kind of problem has prompted repeated calls for some kind of “implements” keyword to indicate that one is intending to implement a protocol requirement. I, personally, *really* don’t want yet another decorator keyword to indicate the intent here, because I believe the user has already indicated intent by stating conformance to the protocol P. I’ve recently committed a number of changes that provide “near-miss” checking for optional requirements of @objc protocols (which have the same problem).</div><div class=""><br class=""></div><div class="">It might be worth enabling this functionality for cases like the above as well. The Swift compiler patch to do so is attached, and will produce the following warning for the code above:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:12:8: </span><span style="font-variant-ligatures: no-common-ligatures; color: #d53bd3" class="">warning: </span><span style="font-variant-ligatures: no-common-ligatures" class="">instance method 'foo(value:)' nearly matches optional requirement 'foo(value:)' of protocol 'P'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foo(value: Double) { }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:12:8: </span><span style="font-variant-ligatures: no-common-ligatures;" class="">note: </span><span style="font-variant-ligatures: no-common-ligatures" class="">candidate has non-matching type '(value: Double) -> ()'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foo(value: Double) { }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:12:8: </span><span style="font-variant-ligatures: no-common-ligatures;" class="">note: </span><span style="font-variant-ligatures: no-common-ligatures" class="">move 'foo(value:)' to another extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foo(value: Double) { }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:12:8: </span><span style="font-variant-ligatures: no-common-ligatures;" class="">note: </span><span style="font-variant-ligatures: no-common-ligatures" class="">make 'foo(value:)' private to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foo(value: Double) { }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> private </span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:2:8: </span><span style="font-variant-ligatures: no-common-ligatures;" class="">note: </span><span style="font-variant-ligatures: no-common-ligatures" class="">requirement 'foo(value:)' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foo(value: Float)</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class="">It’s unfortunate that it’s a lot of notes. The first says what is wrong with the candidate (and there is much we could do to improve the precision of this diagnostic!), while the next two are mitigation strategies: move it to another extension (which implies that it’s not part of the conformance to P) or explicitly mark it as having less visibility than the conformance (in this case, private), which feels like a good way to state “I intend this to be a helper”. This might nudge Swift developers toward a style where they write one conformance per extension, but I don’t think that’s necessarily a bad thing: it’s a fine way to organize code.</div><div class=""><br class=""></div><div class="">Naturally, this handles typos as well, e.g.,</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:12:8: </span><span style="font-variant-ligatures: no-common-ligatures; color: #d53bd3" class="">warning: </span><span style="font-variant-ligatures: no-common-ligatures" class="">instance method 'foob(value:)' nearly matches optional requirement 'foo(value:)' of protocol 'P'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foob(value: Float) { }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(255, 255, 255); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">t2.swift:12:8: </span><span style="font-variant-ligatures: no-common-ligatures;" class="">note: </span><span style="font-variant-ligatures: no-common-ligatures" class="">rename to 'foo(value:)' to satisfy this requirement</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func foob(value: Float) { }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(52, 189, 38); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^~~~</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> foo</span></div></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class="">Running this on the standard library produces a number of results:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: warning: instance method 'removeLast()' nearly matches optional requirement 'removeFirst()' of protocol 'RangeReplaceableCollection'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: note: rename to 'removeFirst()' to satisfy this requirement</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^~~~~~~~~~</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> removeFirst</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: note: move 'removeLast()' to another extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/RangeReplaceableCollection.swift:158:17: note: requirement 'removeFirst()' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> mutating func removeFirst() -> Iterator.Element</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: warning: instance method 'removeLast()' nearly matches optional requirement 'removeFirst()' of protocol 'RangeReplaceableCollection'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: note: rename to 'removeFirst()' to satisfy this requirement</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^~~~~~~~~~</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> removeFirst</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: note: move 'removeLast()' to another extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/RangeReplaceableCollection.swift:158:17: note: requirement 'removeFirst()' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> mutating func removeFirst() -> Iterator.Element</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: warning: instance method 'removeLast()' nearly matches optional requirement 'removeFirst()' of protocol 'RangeReplaceableCollection'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: note: rename to 'removeFirst()' to satisfy this requirement</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^~~~~~~~~~</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> removeFirst</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Arrays.swift.gyb:726:24: note: move 'removeLast()' to another extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public mutating func removeLast() -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/RangeReplaceableCollection.swift:158:17: note: requirement 'removeFirst()' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> mutating func removeFirst() -> Iterator.Element</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/HashedCollections.swift.gyb:1077:10: warning: subscript 'subscript' nearly matches optional requirement 'subscript' of protocol 'Collection'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public subscript(key: Key) -> Value? {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/HashedCollections.swift.gyb:1077:10: note: candidate has non-matching type 'Key -> Value?' [with Iterator = DictionaryIterator<Key, Value>, SubSequence = Slice<Dictionary<Key, Value>>]</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public subscript(key: Key) -> Value? {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/HashedCollections.swift.gyb:1077:10: note: move 'subscript' to an extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public subscript(key: Key) -> Value? {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Collection.swift:147:3: note: requirement 'subscript' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> subscript(bounds: Range<Index>) -> SubSequence { get }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Range.swift:116:10: warning: subscript 'subscript' nearly matches optional requirement 'subscript' of protocol 'Collection'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public subscript(_: Element._DisabledRangeIndex) -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Range.swift:116:10: note: candidate has non-matching type 'Element._DisabledRangeIndex -> Element' [with Iterator = RangeIterator<Element>, SubSequence = Slice<Range<Element>>]</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public subscript(_: Element._DisabledRangeIndex) -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Range.swift:116:10: note: move 'subscript' to an extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public subscript(_: Element._DisabledRangeIndex) -> Element {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Collection.swift:147:3: note: requirement 'subscript' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> subscript(bounds: Range<Index>) -> SubSequence { get }</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/ExistentialCollection.swift.gyb:508:15: warning: instance method '_distance(to:)' nearly matches optional requirement 'distance(to:)' of protocol 'ForwardIndex'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public func _distance(to other: AnyForwardIndex) -> AnyForwardIndex.Distance {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/ExistentialCollection.swift.gyb:508:15: note: rename to 'distance(to:)' to satisfy this requirement [with _DisabledRangeIndex = _DisabledRangeIndex_]</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public func _distance(to other: AnyForwardIndex) -> AnyForwardIndex.Distance {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^~~~~~~~~</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> distance</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/ExistentialCollection.swift.gyb:508:15: note: move '_distance(to:)' to an extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public func _distance(to other: AnyForwardIndex) -> AnyForwardIndex.Distance {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Index.swift:180:8: note: requirement 'distance(to:)' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func distance(to end: Self) -> Distance</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/ExistentialCollection.swift.gyb:508:15: warning: instance method '_distance(to:)' nearly matches optional requirement 'distance(to:)' of protocol 'ForwardIndex'</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public func _distance(to other: AnyBidirectionalIndex) -> AnyBidirectionalIndex.Distance {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/ExistentialCollection.swift.gyb:508:15: note: rename to 'distance(to:)' to satisfy this requirement [with _DisabledRangeIndex = _DisabledRangeIndex_]</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public func _distance(to other: AnyBidirectionalIndex) -> AnyBidirectionalIndex.Distance {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^~~~~~~~~</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> distance</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/ExistentialCollection.swift.gyb:508:15: note: move '_distance(to:)' to an extension to silence this warning</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> public func _distance(to other: AnyBidirectionalIndex) -> AnyBidirectionalIndex.Distance {</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">/Users/dgregor/Projects/swift/swift/stdlib/public/core/Index.swift:180:8: note: requirement 'distance(to:)' declared here</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> func distance(to end: Self) -> Distance</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> ^</span></div><div style="margin: 0px; font-size: 10px; line-height: normal; font-family: Monaco; color: rgb(196, 196, 196); background-color: rgb(0, 0, 0);" class=""><br class=""></div></div><div class=""><br class=""></div><div class="">It’s somewhat frustrating that these are *all* false positives. However, they seem like “reasonable” false positives, in the sense that they’re close enough to the requirement to be justifiable, and the suggested recovery strategies look acceptable.</div><div class=""><br class=""></div><div class="">Thoughts? Should we turn this on?</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>- Doug</div><div class=""><br class=""></div><div class=""></div></div><span id="cid:824122A6-5988-4780-A07A-E69DB17D9BF4@hsd1.co.comcast.net" class=""><default-impl-near-miss.patch></span><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=""><div class=""></div></div>_______________________________________________<br class="">swift-dev mailing list<br class=""><a href="mailto:swift-dev@swift.org" class="">swift-dev@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-dev" class="">https://lists.swift.org/mailman/listinfo/swift-dev</a><br class=""></div></blockquote></div><br class=""></div></div></blockquote></div><br class=""></body></html>