title: Gcc is ignoring -Wno-unused-variable
body: <p>I'm using both <code>gcc version 4.8.3 20140624</code> and <code>gcc4.9.1</code> compiled from trunk. However, the flag doesn't seem to be ignored on <a href="http://coliru.stacked-crooked.com/a/1163d1d0c3718f14" rel="nofollow">online compilers</a>. Here is the test program:</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  int main()
  {
      int i;
  }
  </code></pre>
  
  <p>And shell output:</p>
  
  <pre><code>g++ -std=c++11 -O2 -Wall -Wextra -pedantic -Wno-unused-variable -I./ -c -o test.o test.cpp
  
  test.cpp:6:5: warning: unused parameter ‘argc’ [-Wunused-parameter]
   int main(int argc, char* argv[])
       ^
  test.cpp:6:5: warning: unused parameter ‘argv’ [-Wunused-parameter]
  </code></pre>