title: Is it possible to alias an enum-class enumerator?
body: <p>Given a C++11 enum class, nested inside several long- and ugly-named namespaces:</p>
  <pre><code>namespace
      long_and_ugly
  {
      enum class
          colour
      {
          red,
          green,
          blue
      };
  }
  </code></pre>
  <p>Can aliases be made of the enumeration values? With clang++ 3.5, it is possible to do what follows:</p>
  <pre><code>using long_and_ugly::colour; // take all the values into the current namespace
  using long_and_ugly::colour::red; // take only 'red' into the current namespace
  
  function_taking_colour_argument( red ); // instead of fully referring to the value
  </code></pre>
  <p>g++ 4.9, however, complains. I can't copy its error message because I can't access the code, but it explicitly complained about the usage of the using directive or declaration. I have also tried this:</p>
  <pre><code>using red = long_and_ugly::colour::red;
  </code></pre>
  <p>But it also failed. I'm sorry for not pasting the errors. Nevertheless, I believe you should be able to reproduce it.</p>
  <hr />
  <h3>Question(s)</h3>
  <ul>
  <li><p>Is it possible to declare aliases to enumeration values in standard C++11, or was I using a clang extension?</p>
  </li>
  <li><p>If it is, what is the correct syntax?</p>
  </li>
  </ul>