<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">SGTM.<div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 2017-May-03, at 16:42, Eric Fiselier <<a href="mailto:eric@efcs.ca" class="">eric@efcs.ca</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Hi All,<div class=""><br class=""></div><div class="">Libc++ currently has an ABI incompatibility when built as a static library with no RTTI. Specifically some std::shared_ptr internals have different vtable layouts in this configuration.</div><div class=""><br class=""></div><div class="">I would like to fix this by making the vtable definition consistent across all configurations, but that requires breaking the ABI of a very rare configuration of libc++. I suspect all users of this configuration can take the ABI break immediately, but I would like to confirm this before proceeding.</div><div class=""><br class=""></div><div class="">The configuration in question is a static libc++ library built with -DLIBCXX_ENABLE_RTTI=OFF and -D_LIBCPP_BUILD_STATIC,</div><div class=""><br class=""></div><div class="">Is anybody using this configuration and can't take an ABI break?</div><div class=""><br class=""></div><div class="">Note that `_LIBCPP_BUILD_STATIC` must be manually defined by the user at both when building and using libc++, and it is not supported by the CMake build system. This should mean that almost nobody is defining it.</div><div class=""><br class=""></div><div class="">The proposed changes can be found here: <a href="https://reviews.llvm.org/D32838" class="">https://reviews.llvm.org/D32838</a></div><div class=""><br class=""></div><div class="">/Eric</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div></div>
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