<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 Mar 26, 2017, at 4:23 AM, <a href="mailto:jaden.geller@gmail.com" class="">jaden.geller@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 dir="auto" class=""><div class=""></div><div class=""><br class=""></div><div class=""><br class="">On Mar 25, 2017, at 10:54 PM, John McCall via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><meta http-equiv="Content-Type" content="text/html charset=us-ascii" class=""><div class=""><blockquote type="cite" class=""><div class="">On Mar 25, 2017, at 2:11 AM, Carl Brown1 via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><div class=""><div class=""><p class=""><font size="2" class="">Yes, it would change my opinion of it. I wouldn't become a strong supporter because I don't see any value in it, but a rigorous proof that this proposal could not possibly introduce regressions to any existing codebases would change my opinion from "strongly against" to "doesn't matter to me, I'll stop arguing against it and go get my real work done".</font><br class=""></p></div></div></blockquote><div class="">Speaking just for myself, this was a key part of why I was attracted to this proposal: it seemed to me to be extremely unlikely to cause regressions in behavior. Even without any special behavior in the migrator, code will mostly work exactly as before: things that would have been invalid before will become valid, but not the other way around.</div></div></div></blockquote><div class=""><br class=""></div><div class="">What about overloads that become ambiguous? I admit this is a fringe case.</div></div></div></blockquote><div><br class=""></div>I wouldn't say it's a fringe case. However, if the program no longer type-checks after migration, that's a pretty clear way of informing the user that something funny is going on and they need to look at it. Suppose instead that the program continues to type-check after migration, but now it uses different declarations. If the declarations would previously have inaccessible, recall that I suggested that the migrator could easily detect that and warn the programmer about the change in behavior. If the declarations were previously accessible, and it's just that somehow a new ambiguity caused the type-checker to prefer a different solution — well, that's starting to feel pretty fringe. If we considered things like that to be completely blocking, we'd be unable to ever change the standard library at all.</div><div><br class=""></div><div>Remember that the concern here is just that programs will silently change behavior because of migration. Migration is allowed to say that the programs need to be manually fixed; we just don't want that to happen too often, because it's annoying to have to fix a million things when you update. Is anyone actually arguing that this sort of thing is so pervasive in their code that we need to worry about that?</div><div><br class=""></div><div>John.</div><div><br class=""></div><div><blockquote type="cite" class=""><div class=""><div dir="auto" class=""><br class=""><blockquote type="cite" class=""><div class=""><div class=""><div class="">The exception is that old-private declarations from scopes in the same file can now be found by lookups in different scopes (but still only within the same file). It should be quite straightforward for the migrator to detect when this has happened and report it as something for the programmer to look at. The proposal causes a small regression in functionality, in that there's no longer any way to protect scopes from accesses within the file, but (1) it's okay for Swift to be opinionated about file size and (2) it seems to me that a workable sub-module proposal should solve that more elegantly while simultaneously addressing the concerns of the people who dislike acknowledging the existence of files.</div><div class=""><br class=""></div><div class="">John.</div><blockquote type="cite" class=""><div class=""><div class=""><p class=""><font size="2" class="">-Carl</font><br class=""><br class=""><span id="cid:1__=8FBB0A7DDFB206B68f9e8a93df938690918c8FB@" class=""><graycol.gif></span><font size="2" color="#424282" class="">Xiaodi Wu ---03/25/2017 12:33:55 AM---Would it change your opinion on the proposal? On Sat, Mar 25, 2017 at 12:10 AM, Carl Brown1 <Carl.Br</font><br class=""><br class=""><font size="2" color="#5F5F5F" class="">From: </font><font size="2" class="">Xiaodi Wu <<a href="mailto:xiaodi.wu@gmail.com" class="">xiaodi.wu@gmail.com</a>></font><br class=""><font size="2" color="#5F5F5F" class="">To: </font><font size="2" class="">Carl Brown1/US/IBM@IBM</font><br class=""><font size="2" color="#5F5F5F" class="">Cc: </font><font size="2" class="">Drew Crawford <<a href="mailto:drew@sealedabstract.com" class="">drew@sealedabstract.com</a>>, Jonathan Hull <<a href="mailto:jhull@gbis.com" class="">jhull@gbis.com</a>>, swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>></font><br class=""><font size="2" color="#5F5F5F" class="">Date: </font><font size="2" class="">03/25/2017 12:33 AM</font><br class=""><font size="2" color="#5F5F5F" class="">Subject: </font><font size="2" class="">Re: [swift-evolution] [Review] SE-0159: Fix Private Access Levels</font><br class=""></p><hr width="100%" size="2" align="left" noshade="" style="color:#8091A5; " class=""><br class=""><br class=""><br class="">Would it change your opinion on the proposal?<br class=""><br class=""><br class="">On Sat, Mar 25, 2017 at 12:10 AM, Carl Brown1 <<a href="mailto:Carl.Brown1@ibm.com" target="_blank" class=""><u class=""><font color="#0000FF" class="">Carl.Brown1@ibm.com</font></u></a>> wrote:
<ul class=""><font size="2" class="">I would very much like to see your proof that the resultant code is unchanged in an arbitrary codebase. </font><br class=""><font size="2" class=""><br class="">-Carl</font><br class=""><br class=""><span id="cid:1__=8FBB0A7DDFB206B68f9e8a93df938690918c8FB@" class=""><graycol.gif></span><font size="2" color="#424282" class="">Xiaodi Wu ---03/25/2017 12:01:26 AM---On Fri, Mar 24, 2017 at 11:55 PM, Carl Brown1 <</font><a href="mailto:Carl.Brown1@ibm.com" target="_blank" class=""><u class=""><font size="2" color="#0000FF" class="">Carl.Brown1@ibm.com</font></u></a><font size="2" color="#424282" class="">> wrote: > Maybe this is the core</font><br class=""><font size="2" color="#5F5F5F" class=""><br class="">From: </font><font size="2" class="">Xiaodi Wu <</font><a href="mailto:xiaodi.wu@gmail.com" target="_blank" class=""><u class=""><font size="2" color="#0000FF" class="">xiaodi.wu@gmail.com</font></u></a><font size="2" class="">></font><font size="2" color="#5F5F5F" class=""><br class="">To: </font><font size="2" class="">Carl Brown1/US/IBM@IBM</font><font size="2" color="#5F5F5F" class=""><br class="">Cc: </font><font size="2" class="">Drew Crawford <</font><a href="mailto:drew@sealedabstract.com" target="_blank" class=""><u class=""><font size="2" color="#0000FF" class="">drew@sealedabstract.com</font></u></a><font size="2" class="">>, Jonathan Hull <</font><a href="mailto:jhull@gbis.com" target="_blank" class=""><u class=""><font size="2" color="#0000FF" class="">jhull@gbis.com</font></u></a><font size="2" class="">>, swift-evolution <</font><a href="mailto:swift-evolution@swift.org" target="_blank" class=""><u class=""><font size="2" color="#0000FF" class="">swift-evolution@swift.org</font></u></a><font size="2" class="">></font><font size="2" color="#5F5F5F" class=""><br class="">Date: </font><font size="2" class="">03/25/2017 12:01 AM</font><font size="2" color="#5F5F5F" class=""><br class="">Subject: </font><font size="2" class="">Re: [swift-evolution] [Review] SE-0159: Fix Private Access Levels</font><br class=""><hr width="100%" size="2" align="left" noshade="" class=""><br class=""><br class=""><br class="">On Fri, Mar 24, 2017 at 11:55 PM, Carl Brown1 <<a href="mailto:Carl.Brown1@ibm.com" target="_blank" class=""><u class=""><font color="#0000FF" class="">Carl.Brown1@ibm.com</font></u></a>> wrote:
<p class="">My point is that, in rolling back the specific portion of SE-0025, case-sensitive find-and-replace will be the trickiest thing in most codebases, save those that result in invalid redeclarations. The behavior of the resultant code is, unless I'm mistaken, provably unchanged.
</p><div class=""><br class="webkit-block-placeholder"></div></ul><br class=""><div class=""><br class="webkit-block-placeholder"></div><p class=""><br class="">
</p></div>
_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></div></blockquote></div><br class=""></div></blockquote><blockquote type="cite" class=""><div class=""><span class="">_______________________________________________</span><br class=""><span class="">swift-evolution mailing list</span><br class=""><span class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a></span><br class=""><span class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></span><br class=""></div></blockquote></div></div></blockquote></div><br class=""></body></html>