title: C++ variadic template unusual example
body: <p>What does the following construction mean?</p>
  
  <pre><code>#include &lt;iostream&gt;
  
  template &lt;int ...&gt; struct s;
  
  int main() {
      int i = s&lt;,&gt;::xxx;
  
      std::cout &lt;&lt; i &lt;&lt; std::endl;
  }
  </code></pre>
  
  <p>It is compiled by gcc 4.4.5+ and when executed outputs <code>0</code>.</p>