title: A 'using' declaration with an enum
body: <p>A <em>using</em> declaration does not seem to work with an enum type:</p>
  <pre><code>class Sample{
      public:
          enum Colour {RED, BLUE, GREEN};
  }
  
  using Sample::Colour;
  </code></pre>
  <p>does not work!</p>
  <p>Do we need to add a <em>using</em> declaration for every  enumerators of enum type? Like below:</p>
  <pre><code>using sample::Colour::RED;
  </code></pre>