s="computeroutput"><span class="identifier">vector</span></code>
      looks like a good candidate for such special-case treatment: it's the one standard
      container class where there are good reasons to instantiate it with an incomplete
      type and where Standard Library implementors want to make it work. As of today,
      in fact, implementors would have to go out of their way to prohibit it!</em></span></span>&#8221;</span>
    </p>
<p>
      C++11 standard is also cautious about incomplete types