title: Cannot link with boost in Mac OS X with Clang, c++11
body: <p>I try to compile program using boost with Clang++ on Mac OS X in Qt Creator. Everything goes fine: I have compiled boost and all program modules, but on the linkage stage clang cannot find any symbols:</p>
  
  <pre><code>Undefined symbols for architecture x86_64:
    "_BIO_ctrl", referenced from:
        boost::asio::ssl::detail::engine::map_error_code(boost::system::error_code&amp;) const in session.o
    .....
    "boost::log::v2s_mt_posix::core::get()", referenced from:
        INIT_LOG() in log.o
    .....
  </code></pre>
  
  <p>qmake config:</p>
  
  <pre><code>CONFIG       -= qt
  
  CONFIG       += console debug
  
  TARGET = server
  
  QMAKE_CXXFLAGS -= -mmacosx-version-min=10.6
  QMAKE_CXXFLAGS += -std=c++11 -stdlib=libc++ -mmacosx-version-min=10.7
  QMAKE_LFLAGS -= -mmacosx-version-min=10.6
  QMAKE_LFLAGS += -stdlib=libc++ -mmacosx-version-min=10.7
  </code></pre>
  
  <p>Linking command is:</p>
  
  <p>clang++ -headerpad_max_install_names -stdlib=libc++ -mmacosx-version-min=10.7 -o server main.o session.o log.o -L/Users/apple/Lib/boost_1_53_0/usr/lib -L/opt/local/lib -L/usr/lib -lssl -lboost_system -lboost_filesystem -lboost_date_time -lboost_thread -lboost_log_setup -lboost_log -lboost_chrono -lboost_program_options</p>
  
  <p>If I rename *.dylib, it says that cannot find -lboost_*, so it really SEES library files.</p>
  
  <p>With <code>nm</code> I can find, that symbols exist:</p>
  
  <pre><code>0000000000018ad0 T __ZN5boost3log11v2_mt_posix4core3getEv
  </code></pre>