title: Result type of an implicit conversion must be more specific than AnyRef
body: <p>Let</p>
  
  <pre><code>def h(a: AnyRef*) = a.mkString(",")
  h: (a: AnyRef*)String
  </code></pre>
  
  <p>and so</p>
  
  <pre><code>h("1","2")
  res: String = 1,2
  </code></pre>
  
  <p>However, <code>h(1,2)</code></p>
  
  <pre><code>error: the result type of an implicit conversion must be more specific than AnyRef
                h(1,2)
                  ^
  error: the result type of an implicit conversion must be more specific than AnyRef
                h(1,2)
                    ^
  </code></pre>
  
  <p>This is at least in Scala 2.11.1 and 2.11.1.
  To ask on a workaround.</p>