title: How to use clang-tidy configuration?
body: <p>I cannot use clang-tidy configuration correctly, it always ends up with no output. I use clang-3.9. </p>
  
  <p>If I activate all the checks, it gets me 2752 lines:</p>
  
  <pre><code>clang-tidy test/src/inv.cpp -checks '*' -header-filter '.*' | wc -l  
  2752
  </code></pre>
  
  <p>I then dump the config: </p>
  
  <pre><code>clang-tidy test/src/inv.cpp -checks '*' -header-filter '.*' -dump-config &gt; .clang-tidy
  </code></pre>
  
  <p>And then I try to use it: </p>
  
  <pre><code>clang-tidy test/src/inv.cpp -config ''
  </code></pre>
  
  <p>and it yields no output at all...</p>
  
  <p>The configuration looks OK. 
  How should the clang-tidy configuration be used ? </p>