boost::algorithm::split_regex hangs and consumes CPU on dangling alternatives

main.cpp

#include <stdlib.h>
#include <iostream>
#include <boost/regex.hpp>
#include <boost/algorithm/string/regex.hpp>


int main() {

  // Works
  {
    std::cout << "Using ;|," << std::endl;
    const char *input = "foo;bar,qux";
    std::vector<std::string> result;
    boost::regex pattern(";|,", boost::regbase::normal);
    boost::algorithm::split_regex(result, input, pattern);

    for( int i = 0; i < result.size(); i = i + 1) {
      std::cout << "value at " << i << ": " << result[i] << std::endl;
    }
    std::cout << std::endl;
  }

  // Consumes CPU due to unbounded |
  {
    std::cout << "Using ;|" << std::endl;
    const char *input = "foo;bar,qux";
    std::vector<std::string> result;
    boost::regex pattern(";|", boost::regbase::normal);
    boost::algorithm::split_regex(result, input, pattern);

    for( int i = 0; i < result.size(); i = i + 1) {
      std::cout << "value at " << i << ": " << result[i] << std::endl;
    }
  }
}