title: homebrew list of available compiler
body: <p>Hello I need to compile a <code>Qt</code> project using <code>openmp</code> (built using <code>cmake</code>).</p>
  
  <p>Up to now I used <code>gcc-5</code> provided by <code>homebrew</code> but I would like to use clang (my taste...) </p>
  
  <p>I installed <code>clang-omp</code> via <code>homebrew install clang-omp</code> but now when I try to compile my project (generated via <code>cmake -DCMAKE_CXX_COMPILER=/usr/local/bin/clang-omp++ ..</code>), I get this error:</p>
  
  <pre><code>cd /Users/tommaso/neutrino/debug/src &amp;&amp; /usr/local/bin/clang-omp++   -DHAVE_HDF5 -DHAVE_JPEG -DHAVE_LIBCFITSIO -DHAVE_LIBCLFFT -DHAVE_LIBDF -DHAVE_LIBFFTW -DHAVE_LIBFFTW_THREADS -DHAVE_LIBGSL -DHAVE_LIBGSLCBLAS -DHAVE_LIBHDF5HL -DHAVE_LIBMFHDF -DHAVE_LIBNETPBM -DHAVE_LIBTIFF -DHAVE_NPHYSIMAGE -DHAVE_OPENCL -DHAVE_PYTHONQT -DQT_CORE_LIB -DQT_GUI_LIB -DQT_MULTIMEDIAWIDGETS_LIB -DQT_MULTIMEDIA_LIB -DQT_NETWORK_LIB -DQT_PRINTSUPPORT_LIB -DQT_SQL_LIB -DQT_SVG_LIB -DQT_UIPLUGIN_LIB -DQT_UITOOLS_LIB -DQT_WIDGETS_LIB -DUSE_QT5 -D__VER=\"osx-cmake-v2.0-75.bdff6e3\" -I/Users/tommaso/neutrino/debug/src -I/Users/tommaso/neutrino/src -I/usr/include/hdf -I/usr/local/include/netpbm -I/Library/Frameworks/qwt.framework/Headers -I/usr/local/Cellar/hdf5/1.8.16_1/include -I/usr/include/python2.7 -I/Users/tommaso/neutrino/src/../../pythonqt-code/src -I/Users/tommaso/neutrino/src/../../pythonqt-code/src/gui -I/Users/tommaso/pythonqt-code/src -I/Users/tommaso/pythonqt-code/extensions/PythonQt_QtAll -I/Users/tommaso/neutrino/src/python -iframework /usr/local/opt/qt5/lib -isystem /usr/local/opt/qt5/lib/QtCore.framework/Headers -isystem /usr/local/opt/qt5/./mkspecs/macx-clang -isystem /usr/local/opt/qt5/lib/QtGui.framework/Headers -isystem /System/Library/Frameworks/OpenGL.framework/Headers -isystem /usr/local/opt/qt5/lib/QtSql.framework/Headers -isystem /usr/local/opt/qt5/lib/QtWidgets.framework/Headers -isystem /usr/local/opt/qt5/lib/QtSvg.framework/Headers -isystem /usr/local/opt/qt5/lib/QtPrintSupport.framework/Headers -isystem /usr/local/opt/qt5/include -isystem /usr/local/opt/qt5/include/QtUiTools -isystem /usr/local/opt/qt5/lib/QtMultimedia.framework/Headers -isystem /usr/local/opt/qt5/lib/QtNetwork.framework/Headers -isystem /usr/local/opt/qt5/lib/QtMultimediaWidgets.framework/Headers -I/Users/tommaso/neutrino/debug -I/Users/tommaso/neutrino/src/graphics -I/Users/tommaso/neutrino/src/doc -I/Users/tommaso/neutrino/src/pans -I/Users/tommaso/neutrino/src/pans/VISAR -I/Users/tommaso/neutrino/src/pans/colorbar -I/Users/tommaso/neutrino/src/pans/winlist -I/Users/tommaso/neutrino/src/../nPhysImage -I/Users/tommaso/neutrino/nPhysImage -isystem /usr/local/opt/qt5/lib/QtUiPlugin.framework/Headers  -O3 -fopenmp -fopenmp -O0 -ggdb -D__phys_debug=10   -std=c++11 -Wall -fPIC -mmacosx-version-min=10.6 -o CMakeFiles/Neutrino.dir/neutrino.cc.o -c /Users/tommaso/neutrino/src/neutrino.cc
  
  In file included from /Users/tommaso/neutrino/src/neutrino.cc:26:
  In file included from /usr/local/opt/qt5/lib/QtSvg.framework/Headers/QtSvg:3:
  In file included from /usr/local/opt/qt5/include/QtSvg/QtSvgDepends:3:
  In file included from /usr/local/opt/qt5/include/QtCore/QtCore:4:
  In file included from /usr/local/opt/qt5/lib/QtCore.framework/Headers/qabstractanimation.h:37:
  In file included from /usr/local/opt/qt5/include/QtCore/qobject.h:41:
  /usr/local/opt/qt5/include/QtCore/qstring.h:739:55: error: no type named 'u16string' in namespace 'std'
      static inline QString fromStdU16String(const std::u16string &amp;s);
  </code></pre>
  
  <p>It turns out (correct me if I'm wrong) that I need probably to compile qt with the same <code>clang-omp</code> compiler.</p>
  
  <p>I thought <em>no big deal</em> but <code>homebrew</code> cries when I try this:</p>
  
  <pre><code>HOMEBREW_CC=clang-omp HOMEBREW_CXX=clang-omp++ brew install -s qt5
  Error: Invalid value for HOMEBREW_CC: clang-omp
  </code></pre>
  
  <p>So is there a way to have <code>Qt</code> rebuilt using <code>homebrew</code>?</p>
  
  <p>Is there a command to get the available compilers for <code>homebrew</code>? </p>