No matches with c  11 regex
#include <iostream>
#include <string>
#include <regex>

using namespace std;

int main()
{
    string line("test");
    regex pattern("test",regex_constants::grep);
    smatch result;

    bool ret(false);
    ret = regex_search(line,result,pattern);
    cout <<  boolalpha << ret << endl;
    cout <<  result.size() << endl;
    return 0 ;
}

false
0