title: Is a class with empty body an incomplete type?
body: <p>a class declaration makes the class an incomplete type, so no object of the class could be defined. And the definition of an incomplete type is that its member are not specified. Doesn't that means a class with empty body with no member specified in its definition makes it an incomplete type? </p>
  
  <pre><code>class Empty { };
  
  Empty e1; // okay, but why?
  </code></pre>