title: Why do I get the Regexp warning "warning: nested repeat operator ? and * was replaced with '*'"
body: <p>I have a regular expression for parsing Norwegian street addresses:</p>
  
  <pre><code>STREET_ADDRESS_PATTERN = &lt;&lt;-REGEX
      ^
      (?&lt;street_name&gt;[\w\D\. ]+)\s+
      (?&lt;house_number&gt;\d+)
      (?&lt;entrance&gt;[A-Z])?\s*,\s*
      (
          (?&lt;postal_code&gt;\d{4})\s+
          (?&lt;city&gt;[\w\D ]+)
      )?
      $
  REGEX
  </code></pre>
  
  <p>It worked earlier, and I can't remember if I changed something, and in which case <em>what</em> I changed. In any case, now I'm getting this warning:</p>
  
  <blockquote>
    <p>warning: nested repeat operator ? and * was replaced with '*'</p>
  </blockquote>
  
  <p>And the match is returning <code>nil</code>. Can anybody see why I'm getting this warning?</p>
  
  <hr>
  
  <p><em>Note:</em> I'm currently using this (fake) address to test the expression: "Storgata 38H, 0273 Oslo".</p>