title: "Thread" Boost fails to build on OSX?
body: <p>i'm trying to compile boost 1.57 from source on OSX 10.10.5 but seems to fail to build "thread" lib.</p>
  
  <p><strong>OSX 10.10.5 Yosemite</strong></p>
  
  <p><strong>Xcode 6.1</strong></p>
  
  <p>here is compiling command "</p>
  
  <pre><code>$ ./b2 toolset=clang cxxflags="-arch x86_64 -std=c++11 -stdlib=libstdc++ -ftemplate-depth=512" linkflags="-stdlib=libstdc++" link=static install --with-program_options --with-system --with-filesystem --with-chrono --with-thread
  </code></pre>
  
  <p><strong>Error :</strong></p>
  
  <pre><code>clang-darwin.compile.c++ bin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi/pthread/thread.o
  In file included from libs/thread/src/pthread/thread.cpp:11:
  In file included from ./boost/thread/thread_only.hpp:17:
  In file included from ./boost/thread/pthread/thread_data.hpp:11:
  In file included from ./boost/thread/lock_guard.hpp:12:
  ./boost/thread/detail/move.hpp:31:10: fatal error: 'type_traits' file not found
  #include &lt;type_traits&gt;
           ^
  1 error generated.
  
      "clang++" -x c++ -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -arch x86_64 -std=c++11 -stdlib=libstdc++ -ftemplate-depth=512 -O3 -O3 -finline-functions -Wno-inline -Wall -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp"
  
  ...failed clang-darwin.compile.c++ bin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi/pthread/thread.o...
  clang-darwin.compile.c++ bin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi/pthread/once.o
  In file included from libs/thread/src/pthread/once.cpp:8:
  In file included from libs/thread/src/pthread/./once_atomic.cpp:9:
  In file included from ./boost/thread/once.hpp:20:
  In file included from ./boost/thread/pthread/once_atomic.hpp:16:
  ./boost/thread/detail/move.hpp:31:10: fatal error: 'type_traits' file not found
  #include &lt;type_traits&gt;
           ^
  1 error generated.
  
      "clang++" -x c++ -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -arch x86_64 -std=c++11 -stdlib=libstdc++ -ftemplate-depth=512 -O3 -O3 -finline-functions -Wno-inline -Wall -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi/pthread/once.o" "libs/thread/src/pthread/once.cpp"
  
  ...failed clang-darwin.compile.c++ bin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi/pthread/once.o...
  ...skipped &lt;pbin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi&gt;libboost_thread.a(clean) for lack of &lt;pbin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi&gt;pthread/thread.o...
  ...skipped &lt;pbin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi&gt;libboost_thread.a for lack of &lt;pbin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi&gt;pthread/thread.o...
  ...skipped &lt;p/usr/local/lib&gt;libboost_thread.a for lack of &lt;pbin.v2/libs/thread/build/clang-darwin-4.2.1/release/link-static/threading-multi&gt;libboost_thread.a...
  ...failed updating 2 targets...
  ...skipped 3 targets...
  </code></pre>
  
  <p>What do you think is the problem ?</p>