Add a CK_BaseToDerived cast kind.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86994 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index a8ea752..d43d58a 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -490,6 +490,8 @@
     return "BitCast";
   case CastExpr::CK_NoOp:
     return "NoOp";
+  case CastExpr::CK_BaseToDerived:
+    return "BaseToDerived";
   case CastExpr::CK_DerivedToBase:
     return "DerivedToBase";
   case CastExpr::CK_Dynamic: