auto | operator() (Tup &&tup, Val val, Fun fun) const noexcept(noexcept(decltype(tuple_foldl_fn::impl2(static_cast< Tup &&>(tup), std::move(val), fun, tuple_indices_t< Tup >{}))(tuple_foldl_fn::impl2(static_cast< Tup &&>(tup), std::move(val), fun, tuple_indices_t< Tup >{})))) -> decltype(tuple_foldl_fn::impl2(static_cast< Tup &&>(tup), std::move(val), fun, tuple_indices_t< Tup > |