Boost version: 1.54.0

OK.cc

#include <iostream>
#include <boost/spirit/include/qi.hpp>

namespace qi = boost::spirit::qi;

int main() {
  auto word = qi::raw[+qi::graph];
  auto rule = qi::omit[*qi::space] >> word >> qi::omit[+qi::space];
  std::string s = "  hoge  fuga";

  auto iter = s.begin();
  std::vector<std::string> results;
  bool success = qi::parse(iter, s.end(), rule, results);
  if (success) {
    for (auto const& result : results) {
      std::cout << result << std::endl;
    }
  } else {
    std::cout << "parse error\n";
  }
}

SEGV.cc

#include <iostream>
#include <boost/spirit/include/qi.hpp>

namespace qi = boost::spirit::qi;

int main() {
  auto word = qi::raw[+qi::graph];
  auto rule = qi::omit[*qi::space] >> word >> qi::omit[+qi::space] >> word;
  std::string s = "  hoge  fuga";

  auto iter = s.begin();
  std::vector<std::string> results;
  bool success = qi::parse(iter, s.end(), rule, results);
  if (success) {
    for (auto const& result : results) {
      std::cout << result << std::endl;
    }
  } else {
    std::cout << "parse error\n";
  }
}