title: missing complete candidate for c++-mode with company-mode
body: <p><a href="https://i.stack.imgur.com/6cfkL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6cfkL.png" alt="enter image description here"></a></p>
  
  <p>As the picture shows above, it has missed the <code>operator=(const Name &amp;other)</code> candidate.</p>
  
  <p>Confused!</p>