<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 just pushed f5c1d4409e013f and updated the Chromium bug report. Let's continue the discussion at <a href="https://bugs.chromium.org/p/chromium/issues/detail?id=1067216" class="">https://bugs.chromium.org/p/chromium/issues/detail?id=1067216</a> to centralize things.<div class=""><br class=""></div><div class="">Louis<br class=""><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Apr 2, 2020, at 13:07, Louis Dionne via libcxx-commits <<a href="mailto:libcxx-commits@lists.llvm.org" class="">libcxx-commits@lists.llvm.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class=""><br class=""><br class=""><blockquote type="cite" class="">On Apr 2, 2020, at 13:04, Hans Wennborg <<a href="mailto:hans@chromium.org" class="">hans@chromium.org</a>> wrote:<br class=""><br class="">On Thu, Apr 2, 2020 at 7:01 PM Louis Dionne <<a href="mailto:ldionne@apple.com" class="">ldionne@apple.com</a>> wrote:<br class=""><blockquote type="cite" class=""><br class=""><br class=""><br class=""><blockquote type="cite" class="">On Apr 2, 2020, at 12:54, Hans Wennborg <<a href="mailto:hans@chromium.org" class="">hans@chromium.org</a>> wrote:<br class=""><br class="">On Thu, Apr 2, 2020 at 8:21 AM Louis Dionne via libcxx-commits<br class=""><<a href="mailto:libcxx-commits@lists.llvm.org" class="">libcxx-commits@lists.llvm.org</a>> wrote:<br class=""><blockquote type="cite" class=""><br class=""><br class="">Author: Louis Dionne<br class="">Date: 2020-04-02T02:21:15-04:00<br class="">New Revision: 61e89737c5daf7b65341936f88f68efb680cdcd4<br class=""><br class="">URL: <a href="https://github.com/llvm/llvm-project/commit/61e89737c5daf7b65341936f88f68efb680cdcd4" class="">https://github.com/llvm/llvm-project/commit/61e89737c5daf7b65341936f88f68efb680cdcd4</a><br class="">DIFF: <a href="https://github.com/llvm/llvm-project/commit/61e89737c5daf7b65341936f88f68efb680cdcd4.diff" class="">https://github.com/llvm/llvm-project/commit/61e89737c5daf7b65341936f88f68efb680cdcd4.diff</a><br class=""><br class="">LOG: [libc++] Simplify the configuration of the C++ ABI library<br class=""><br class="">This commit removes support for building against the system libc++abi,<br class="">which was supported on Apple platforms. This is basically never what we<br class="">want to do, since libc++ and libc++abi are coupled and building a trunk<br class="">libc++ against an older libc++abi can lead to incompatibilities (and<br class="">good luck debugging them!). It might have made some sense to support<br class="">that when the monorepo did not exist, however I don't think this is<br class="">anything but a footgun nowadays.<br class=""><br class="">Furthermore, based on the newly-made assumption that we're building<br class="">against the monorepo libc++abi, we can simplify the search path logic<br class="">for finding libc++abi.<br class=""><br class="">This area of our build system has a lot of technical debt accumulated,<br class="">and it's surprisingly difficult to change. We've tried different things<br class="">and failed several times in the past. I did test this change on our<br class="">Docker image for the build bots and on Apple platforms, however it is<br class="">possible that this breaks some unknown configuration, in which case it<br class="">should be fine to revert this (so we can try again!).<br class=""></blockquote><br class="">Well hello :-)<br class=""><br class="">This broke Chromium's packaging of Clang on Mac (see <a href="https://crbug.com/1067216" class="">https://crbug.com/1067216</a>).<br class=""><br class="">We build libc++ as part of that process, not because we ship it with<br class="">the compiler, but as part of the bootstrapping process: otherwise the<br class="">just-built Clang doesn't find the c++ headers. Until now we've been<br class="">building with -DLIBCXX_CXX_ABI=libcxxabi -DLIBCXX_CXX_ABI_SYSTEM=1<br class="">however with your patch that stopped working.<br class=""><br class="">I tried adding libcxxabi to -DLLVM_ENABLE_PROJECTS and dropping those<br class="">two flags, but now building libcxxabi failed for unclear reasons<br class="">([1]).<br class=""><br class="">Would it be okay to revert your patch until we've figured this out?<br class=""></blockquote><br class="">We've already applied a couple of patches on top and fixed other failing bots -- we're farther than we've ever been. Any chance of catching you on IM before we revert? I'm trying to repro your failure and I think I'll be able to submit a patch soon (max ~1h).<br class=""></blockquote><br class="">I just realized the failure I'm seeing is maybe<br class=""><a href="https://bugs.llvm.org/show_bug.cgi?id=42725" class="">https://bugs.llvm.org/show_bug.cgi?id=42725</a><br class=""><br class="">The clang used on that machine is identified by cmake as AppleClang<br class="">9.0.0.9000037. I'm not entirely sure how to upgrade that, so if you<br class="">have other ideas for how to fix, that would be great.<br class=""></blockquote><br class="">No, it's not that. I know pretty much exactly what the issue is (I've repro'd), and I'm working on a patch. Once the dust has settled, we'll have to work together to get your libc++ build standardized, though, because LIBCXX_CXX_ABI_SYSTEM is not a publicly tweakable variable for libc++. I think I know what underlying issue you're working around and I think I know the proper fix, which wouldn't require building libc++ at all (since that's not really what you want anyway IIUC).<br class=""><br class="">Louis<br class=""><br class="">_______________________________________________<br class="">libcxx-commits mailing list<br class=""><a href="mailto:libcxx-commits@lists.llvm.org" class="">libcxx-commits@lists.llvm.org</a><br class="">https://lists.llvm.org/cgi-bin/mailman/listinfo/libcxx-commits<br class=""></div></div></blockquote></div><br class=""></div></div></body></html>