Handle __extension__ as a unary operator if requested.

llvm-svn: 39050
diff --git a/clang/Sema/Sema.cpp b/clang/Sema/Sema.cpp
index 17fa8d3..88d3168 100644
--- a/clang/Sema/Sema.cpp
+++ b/clang/Sema/Sema.cpp
@@ -277,6 +277,10 @@
   case tok::kw___real:    Opc = UnaryOperator::Real; break;
   case tok::kw___imag:    Opc = UnaryOperator::Imag; break;
   case tok::ampamp:       Opc = UnaryOperator::AddrLabel; break;
+  case tok::kw___extension__: 
+    if (!FullLocInfo) return Input;
+    Opc = UnaryOperator::Extension;
+    break;
   }
 
   if (!FullLocInfo)