title: How to query the default include paths of clang++?
body: <p>How can I query the default include path of clang/clang++? I am trying to use a custom built clang compiler (the one that supports OpenMP), but it doesn't seem to find the STL libraries: </p>
  
  <pre><code>/usr/local/bin/clang++ hello.cpp 
  hello.cpp:1:10: fatal error: 'iostream' file not found
  #include &lt;iostream&gt;
       ^
  1 error generated.
  </code></pre>
  
  <p>By using an IDE, back-tracking the #include iostream, and finally using the <strong>-isystem</strong> option I got the simple helloworld application to compile in OSX 10.9:</p>
  
  <pre><code>/usr/local/bin/clang++ -isystem /Library/Developer/CommandLineTools/usr/lib/c++/v1 hello.cpp
  </code></pre>
  
  <p>Thanks for your help!</p>