title: What is the assign-enum warning in clang?
body: <p>I was going through <code>AFNetworking</code> implementation and I found this</p>
  
  <pre><code>#pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wassign-enum"
  [request setHTTPBody:[NSJSONSerialization dataWithJSONObject:parameters options:0 error:&amp;error]];
  #pragma clang diagnostic pop
  </code></pre>
  
  <p>(<a href="https://github.com/AFNetworking/AFNetworking/blob/master/AFNetworking/AFHTTPClient.m#L490">AFHTTPClient:489-492</a>)</p>
  
  <p>The <code>assign-enum</code> warning is obviously being turned off, but I wonder what does it mean.</p>
  
  <p>What is the warning thrown by clang in that case?</p>