I am using Boost Spirit X3 to create a programming language, but when I try to support Unicode, I get an error!
Here is an example of a simplified version of that program.

#define BOOST_SPIRIT_X3_UNICODE
#include <boost/spirit/home/x3.hpp>

namespace x3 = boost::spirit::x3;

struct sample : x3::symbols<unsigned> {
    sample()
    {
        add("48", 10);
    }
};

int main()
{
  const std::string s("