title: shared_ptr aliasing constructor
body: <p>Question about following <code>shared_ptr</code> constructor:</p>
  
  <pre><code>template&lt; class Y &gt;
  shared_ptr( const shared_ptr&lt;Y&gt;&amp; r, T *ptr );
  </code></pre>
  
  <p>Am I correct that if <code>r</code> was created using user-provided deleter, then aliasing <code>shared_ptr</code> knows that. So if aliasing <code>shared_ptr</code> is last in the group and (when going out of scope) destructs resources originally managed by <code>r</code>, it will use that user-provided deleter?</p>