Bug 718711

Can someone at least confirm this, or point out if there is an error in how I used it?

Benjamin, could you please look at this?  Thanks.

Confirmed. I don't see an error in usage, this is a bug in libstdc++'s <regex>.
I've opened up an upstream bug report here:

 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49870

As a temporary work-around, you can use boost's regex, which has the same interface but gives the correct result. Here's your example with that component:

#include <boost/regex.hpp>
#include <regex>
#include <cstdio>

// compile like
// g++ -std=gnu++0x -g -O2 71871-regex.cpp -lboost_regex -Wfatal-errors


// execute like
// ./a.out "foo.*" "foobar" 
// ./a.out "^foo.*" "foobar" 
int
main(int argc, char **argv)
{
  
  // 1 std
  {
    std::regex expr(argv[1], std::regex_constants::extended);
    std::string test_string = argv[2];
    printf("Applying regex '%s' to string '%s'\n", argv[1], argv[2]);
    
    if (std::regex_match(test_string, expr)) 
      printf("C++: Match\n");
    else 
      printf("C++: NO match\n");
  }

  // 2 boost
  {
    boost::regex expr(argv[1], boost::regex_constants::extended);
    std::string test_string = argv[2];
    printf("Applying regex '%s' to string '%s'\n", argv[1], argv[2]);

    if (boost::regex_match(test_string, expr)) 
      printf("C++: Match\n");
    else 
      printf("C++: NO match\n");
  }

  return 0;
}

Tracked upstream.