C++ Mathematical Expression Library (ExprTk)  http://www.partow.net/programming/exprtk/index.html

exprtk.hpp

diff --git a/exprtk.hpp b/exprtk.hpp
index d7964cf..c5411e7 100644
--- a/exprtk.hpp
+++ b/exprtk.hpp
@@ -19545,7 +19545,7 @@
 
                // Remove all subexpressions after first encountered return node.
 
-               for (std::size_t j = i + 1; j < (expression_list.size() - 1); ++j)
+               for (std::size_t j = i + 1; j < expression_list.size(); ++j)
                {
                   free_node(node_allocator_,expression_list[j]);
                }