title: Why would one disable variance checking via @uV?
body: <p>I just stumbled over the following definition of method <code>to</code> defined by <a href="https://github.com/scala/scala/blob/v2.10.0/src/library/scala/collection/TraversableLike.scala" rel="nofollow noreferrer"><code>TraversableLike</code></a> (2.10.0):</p>
  
  <pre><code>override def to[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A @uV]]): Col[A @uV] = {
    val b = cbf()
    b.sizeHint(this)
    b ++= thisCollection
    b.result
  }
  </code></pre>
  
  <p>According to <a href="https://stackoverflow.com/a/8761517/491216">this answer</a>, the <code>@uV</code> disabled variance checking. That sounds dangerous. Why would I want to do that?</p>