<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">I'm looking for all code that uses the is-Swift bit in class metadata.<div class=""><br class=""></div><div class="">Uses that I know of:</div><div class="">* Compiler-generated class metadata (addClassDataPointer() in GenMeta.cpp)</div><div class="">* Runtime metadata checks (isTypeMetadata() inMetadata.h)</div><div class="">* Stuff in lldb and other debugging tools</div><div class="">* Stuff in the Objective-C runtime</div><div class=""><br class=""></div><div class="">Is there any other code that reads or writes this bit? Does compiler-generated code ever do so? Or maybe something in reflection that I haven't found?</div><div class=""><br class=""></div><div class="">(Backstory: The forthcoming stable Swift ABI will need to use a different bit to avoid collisions with existing pre-stable-ABI Swift apps. We will need to find all of these locations and change them.)</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">-- </div><div class="">Greg Parker <a href="mailto:gparker@apple.com" class="">gparker@apple.com</a> Runtime Wrangler</div><div class=""><br class=""></div><div class=""><br class=""></div></body></html>