title: The call is ambiguous between single method i.e extension method
body: <p>I have an extension method like</p>
  
  <pre><code>public static class Extension
  {
      public static string GetTLD(this string str)
      {
          var host = new System.Uri(str).Host;
          int index = host.LastIndexOf('.'), last = 3;
          while (index &gt;= last - 3)
          {
              last = index;
              index = host.LastIndexOf('.', last - 1);
          }
          var domain = host.Substring(index + 1);
          return domain;
      }
  }
  </code></pre>
  
  <p>And I am calling this like</p>
  
  <pre><code>string domain = "." + _url.GetTLD();
  </code></pre>
  
  <p>I am getting no error at building and clean build.<br>
  But I am getting <code>compilation error</code> at run time error saying</p>
  
  <blockquote>
    <p>The call is ambiguous between the following methods or properties:
    'myIGNOU.Extension.GetTLD(string)' and
    'myIGNOU.Extension.GetTLD(string)'</p>
  </blockquote>
  
  <p>I swear that I don't have this extension method placed any where else too in the project.
  Why I am getting this error only at run time..?</p>
  
  <p>But if I delete this method then I am getting error at build time not not at run time. Everything works fine without the code of this method.</p>
  
  <p><a href="https://www.dropbox.com/s/tndh2zqzim01bj4/Compilation%20Error.htm">Here is compilation error page</a></p>