Dean Michael Berris wrote:
Would there be a way to determine whether the user is using libstdc++ on the Mac from Boost.Config?
I distinctly remember that most standard Mac OS X installations come with a frozen version of libstdc++ (GCC's 4.2) which has patches from Apple. Apple's Clang I supports C++11 but only really works if you link with libc++ (or maybe if you get an updated libstdc++ with patches to work on OS X with clang). Being able to check the version of libstdc++ being used should give you a better way of making this determination.
This is what libstdcpp3.hpp has to say on the matter: // stdlibc++ C++0x support is detected via __GNUC__, __GNUC_MINOR__, and possibly // __GNUC_PATCHLEVEL__ at the suggestion of Jonathan Wakely, one of the stdlibc++ // developers. He also commented: // // "I'm not sure how useful __GLIBCXX__ is for your purposes, for instance in // GCC 4.2.4 it is set to 20080519 but in GCC 4.3.0 it is set to 20080305. // Although 4.3.0 was released earlier than 4.2.4, it has better C++0x support // than any release in the 4.2 series." // // Another resource for understanding stdlibc++ features is: // http://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#manual.intro.stat... It uses the compiler version to determine library features. Now... according to gcc.hpp, nullptr (and by assumption std::nullptr_t) first appeared in g++ 4.6, so if we set BOOST_NO_CXX11_NULLPTR_T for pre-4.6 in libstdcpp3.hpp and if Apple's clang defines its GCC version as 4.2, as I suspect it would, then it might work. But I have no way to check.