OK, it turns out that BOOST_HAS_THREADS *was* getting enabled, but was later getting disabled in suffix.hpp because BOOST_HAS_PTHREADS was not enabled. I believe that it should be enabled by the inclusion of posix_features.hpp, but this is not happening because of this test in macos.hpp: # ifndef TARGET_CARBON # include <boost/config/posix_features.hpp> # endif I'm building a Cocoa project in Xcode, which apparently defines TARGET_CARBON for me. Why is posix_features.hpp only included if TARGET_CARBON is not defined? You can use posix from a carbon target just fine. Commenting out the #ifndef so posix_features.hpp is included makes it build and work just fine. Is there some reason for this that I'm not seeing? Is this a bug?
I don't know enough (well anything really!) about MacOS targets, and what is and is not correct for them, searching the archives it appears that I added this check after a user request: http://lists.boost.org/MailArchives/boost-users/msg02664.php. Obviously we need a better way of doing things, so any suggestions welcome... Thanks, John.