Thanks to Chandler for reminding me to update the documentation for the

__underlying_type feature.

llvm-svn: 135402

clang/docs/LanguageExtensions.html

@@ -599,6 +599,7 @@ struct is_convertible_to {
   <li><code>__is_polymorphic</code> (GNU, Microsoft)</li>
   <li><code>__is_union</code> (GNU, Microsoft)</li>
   <li><code>__is_literal(type)</code>: Determines whether the given type is a literal type</li>
+  <li><code>__underlying_type(type)</code>: Retrieves the underlying type for a given <code>enum</code> type. This trait is required to implement the C++0x standard library.</li>
 </ul>
 
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