Implement __underlying_type for libc++.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131633 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index d7b90f1..eadd546 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -1859,6 +1859,9 @@
       ParseDecltypeSpecifier(DS);
       continue;
 
+    case tok::kw___underlying_type:
+      ParseUnderlyingTypeSpecifier(DS);
+
     // OpenCL qualifiers:
     case tok::kw_private: 
       if (!getLang().OpenCL)
@@ -2129,6 +2132,11 @@
     ParseDecltypeSpecifier(DS);
     return true;
 
+  // C++0x type traits support.
+  case tok::kw___underlying_type:
+    ParseUnderlyingTypeSpecifier(DS);
+    return true;
+
   // OpenCL qualifiers:
   case tok::kw_private: 
     if (!getLang().OpenCL)