title: How to define a type alias for a template in a class
body: <p>For example</p>
  
  <pre><code>struct Option_1
  {
      template&lt;class T&gt; using Vector = std::vector&lt;T&gt;;
  };
  </code></pre>
  
  <p>I can do</p>
  
  <pre><code>typename Option_1::Vector&lt;int&gt; v;
  </code></pre>
  
  <p>But I prefer the following</p>
  
  <pre><code>Vector&lt;Option_1, int&gt; v;
  </code></pre>
  
  <p>or similars without the word "typename". I define an alias</p>
  
  <pre><code>template&lt;class Option, class T&gt; using Vector= typename Option::Vector&lt;T&gt;;
  </code></pre>
  
  <p>but failed with unrecognizable template declaration/definition. How to fix it?</p>