<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">On Jan 8, 2018, at 11:07 PM, Nate Cook <<a href="mailto:nate@natecook.com" class="">nate@natecook.com</a>> wrote:<div><blockquote type="cite" class=""><div class=""><div dir="auto" class="Singleton"><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class=""><div class=""><div class=""><blockquote type="cite" class=""><div class=""><div class=""><br class="">The old name can live on indefinitely via a typealias (which has no ABI consequences, so could be retired at a later date once everyone has had plenty of time to address the deprecation warnings). Removing it as not carrying its weight (and instead using `[(Key,Value)]`, which is basically what it’s a wrapper for) is probably off the table for source stability reasons.<br class=""></div></div></blockquote></div><br class=""><div class="">I’m not familiar with this type at all, so I apologize for the dumb question but… why was this added in the first place? If it is the wrong thing, why not just deprecate it in Swift 5 and remove it in a future release? That avoids it being an ABI concern, because we could make it be force inlined into any client code.</div></div></blockquote><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">According to now-gone doc comments, it's intended to be used when providing the children for a custom mirror (that's the only API I know of that uses the type). The order of elements there is important, but given how scarcely used the type is, an array of tuples might be a reasonable (though source-breaking) substitute. </div><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: 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-size-adjust: auto; -webkit-text-stroke-width: 0px;" class=""><div class=""><div class="">Finally, is anyone actually using this type?</div></div></blockquote><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">In the standard library, we have this Mirror initializer: <a href="https://developer.apple.com/documentation/swift/mirror/1540408-init" class="">https://developer.apple.com/documentation/swift/mirror/1540408-init</a>. If anyone is customizing their type's mirror, it's a good bet that they're calling that init and passing a literal that would break if the argument changed to an array. The translation should be mechanical, so maybe it could be a migrator fix? (I don't know enough about how that works to know.)</div></div></div></blockquote><br class=""></div><div>Ah I see. What is the plan for Mirrors? I thought they had numerous known deficiencies and should be replaced with a better reflection system. Are they going to make the jump to ABI stability?</div><div><br class=""></div><div>-Chris</div><div><br class=""></div></body></html>