class="tm-cmt">// x is D here</span>
  }
  <span class="tm-kw">else</span> {
    <span class="tm-cmt">// x is still just C here</span>
  }
}<hr class="error-divider"><div class="listed-error"><div class="error-line">Cannot find name 'C'.</div></div><div class="listed-error"><div class="error-line">Cannot find name 'C'.</div></div><a class="playground-link" href="https://www.typescriptlang.org/play/#src=class%20D%20extends%20C%20%7B%20d%3A%20any%20%7D%0Afunction%20f(x%3A%20C)%20%7B%0A%20%20if%20(x%20instance