[c++1z] N4295: fold-expressions.

This is a new form of expression of the form:

  (expr op ... op expr)

where one of the exprs is a parameter pack. It expands into

  (expr1 op (expr2onwards op ... op expr))

(and likewise if the pack is on the right). The non-pack operand can be
omitted; in that case, an empty pack gives a fallback value or an error,
depending on the operator.

llvm-svn: 221573
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index d49d9b2..2ce5ac5 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -8661,6 +8661,7 @@
   case Expr::PseudoObjectExprClass:
   case Expr::AtomicExprClass:
   case Expr::LambdaExprClass:
+  case Expr::CXXFoldExprClass:
     return ICEDiag(IK_NotICE, E->getLocStart());
 
   case Expr::InitListExprClass: {