Hi! I'm using clang + libc++ on Linux and the Predef "check" magic activates "BOOST_MAC_OS". That means I get: Performing configuration checks - symlinks supported : yes warn: Unable to construct ./info_as_objcpp warn: Unable to construct ./info_as_objc - BOOST_OS_MACOS : yes when running the predef test suite. Command chain: cd libs/predef/test rm -rf ../../../bin.v2/libs/predef/ ../../../bin.v2/check/ ../../../bin.v2/project-cache.jam b2 -a --verbose-test 2>&1 -d+2 --debug-configuration | tee verbose.log verbose.log is attached as zip file. And in fact the macos test are run: clang-linux.compile.c.without-pth BOOST_ROOT/src/devel/boost/bin.v2/libs/predef/test/macos_endian.test/clang- linux-3.7.0/debug/macos_endian.o which is only supposed to be run on macos. The test even passes because it internally checks for "__APPLE__" being defined, which should probably be removed, as the check should be done by the build system. Compiler: clang++ -v clang version 3.7.0 (trunk 227683) Target: x86_64-unknown-linux-gnu Thread model: posix That is current clang trunk. Though I'm already running with -d+2 --debug-configuration I get no output from the configuration test itself. Any ideas on how to debug this further? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! * voice: ++49 4257 300 ! Fährstraße 1 * fax : ++49 4257 300 ! 31609 Balge/Sebbenhausen * jhunold@gmx.eu ! Germany