#include <boost/phoenix/core.hpp>
#include <boost/phoenix/operator.hpp>

// Without this include, the program prints 1. With it, it prints 2.
//#include <boost/phoenix/scope.hpp>

#include <iostream>

using namespace boost::phoenix::arg_names;

int main()
{
  int a;
  (++arg1, ++arg1)(a);
  std::cout << a << std::endl;
}