<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 12, 2017 at 9:29 AM, Rene Rivera via Boost-build <span dir="ltr"><<a href="mailto:boost-build@lists.boost.org" target="_blank">boost-build@lists.boost.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">There's been a long standing "issue" with how the b2 configure checks work. Or rather how some times they don't work. In particular the issue is that the set of properties considered relevant for the configuration checks was fixed. As of last night that is now resolved <<a href="https://github.com/boostorg/build/commit/450c25c3b52f5ddcb323140f8423adf3b85b6b1a" target="_blank">https://github.com/boostorg/b<wbr>uild/commit/450c25c3b52f5ddcb3<wbr>23140f8423adf3b85b6b1a</a>>.<div><br></div><div>As the commit mentions the set is no longer fixed and is configurable by users. The changes now mean that:</div><div><br></div><div>1. Any subfeatures of the top level relevant feature set are also considered as part of the set. This means that one can a configuration like below to support multiple invocations of the same toolset with different options. In particular the STD options:</div><div><br></div><div>=== user-config.jam ===</div><div>import feature ;</div><div><div>using clang ;</div><div>feature.subfeature toolset clang : std : cxx03 cxx11 cxx14 cxx17 : optional composite propagated ;<br></div><div>feature.compose <toolset-clang:std>cxx03 : <cxxflags>-std=c++03 ;<br></div><div>feature.compose <toolset-clang:std>cxx11 : <cxxflags>-std=c++11 ;</div><div>feature.compose <toolset-clang:std>cxx14 : <cxxflags>-std=c++14 ;</div><div>===</div><div><br></div><div>And one can then invoke "b2 toolset=clang-cxx14,clang-cxx1<wbr>1" and get non-colliding configuration checks.</div></div></div></blockquote><div><br></div><div>This sounds very cool. I'd like to start using it, but hoping for some more details. Specifically how does it work with version numbers? With the above user-config.jam could I invoke "b2 toolset=clang-3.8-cxx11,clang-<wbr>3.9-cxx14"? Does this work on the msvc side as well...the version number detection seems a bit more rough there?<br></div><div><br></div><div>Or do I need to do something version specific for each version in my user-config.jam? </div><div><div>=== user-config.jam ===</div><div>import feature ;</div><div><div>using clang : 3.8 ;</div><div>feature.subfeature toolset clang-3.8 : std : cxx03 cxx11 : optional composite propagated ;<br></div><div>feature.compose <toolset-clang-3.8:std>cxx03 : <cxxflags>-std=c++03 ;<br></div><div>feature.compose <toolset-clang-3.8:std>cxx11 : <cxxflags>-std=c++11 ;</div><div><br class="m_448068560637222500gmail-Apple-interchange-newline">using clang : 3.9 ;</div><div>feature.subfeature toolset clang-3.9 : std : cxx14 cxx1z : optional composite propagated ;<br></div><div>feature.compose <toolset-clang-3.9:std>cxx14 : <cxxflags>-std=c++14 ;<br></div><div>feature.compose <toolset-clang-3.9:std>cxx1z : <cxxflags>-std=c++1z ;</div><div>===</div></div></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><div><br></div><div>2. The set of relevant features is now soft wired as the set of subfeatures of the "<composite>" feature. Which means ones can add to the default set <<a href="https://github.com/boostorg/build/blob/develop/src/build/configure.jam#L26" target="_blank">https://github.com/boostorg/b<wbr>uild/blob/develop/src/build/co<wbr>nfigure.jam#L26</a>>. For example to add threading choice to the relevant features:</div><div><br></div><div>=== user-config.jam ===</div><div>import feature ;</div><div>import configure ;</div><div>feature.compose <configure> : <threading> ;</div><div>===</div></div></div></blockquote><div><br></div><div>I'm not entirely clear on what this means, could you give an example of what this implies?</div><div><br></div><div>Thanks,</div><div>Tom </div></div></div></div>