Implement support for pack expansions whose pattern is a non-type
template argument (described by an expression, of course). For
example:

  template<int...> struct int_tuple { };

  template<int ...Values>
  struct square {
    typedef int_tuple<(Values*Values)...> type;
  };

It also lays the foundation for pack expansions in an initializer-list.
  

llvm-svn: 122751
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 8797880..c39b398 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -2634,6 +2634,7 @@
   case Expr::BlockDeclRefExprClass:
   case Expr::NoStmtClass:
   case Expr::OpaqueValueExprClass:
+  case Expr::PackExpansionExprClass:
     return ICEDiag(2, E->getLocStart());
 
   case Expr::GNUNullExprClass: