title: Rule reference is not currently supported in a set in ANTLR4 Grammar
body: <p>I am trying to port <a href="http://www.antlr3.org/grammar/1206736738015/JavaScript.g" rel="noreferrer">Chris Lambro's <code>ANTLR3</code> Javascript Grammar</a> to <code>ANTLR4</code></p>
  
  <p>I am getting the following error,</p>
  
  <blockquote>
    <p>Rule reference 'LT' is not currently supported in a set</p>
  </blockquote>
  
  <p>in the following code <code>~(LT)*</code></p>
  
  <pre><code>LineComment
      : '//'  ~(LT)* -&gt; skip
      ;
  
  LT  : '\n'      // Line feed.
      | '\r'      // Carriage return.
      | '\u2028'  // Line separator.
      | '\u2029'  // Paragraph separator.
      ;
  </code></pre>
  
  <p>I need help understanding why I am getting this error, and how I can solve it .</p>