https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79522
--- Comment #1 from Jim Michaels <jmichae3 at yahoo dot com> --- Tue 02/14/2017 23:45:45.01 L:\projects\find\1.0\win>g++ -static -lstdc++ -std=c++11 -o ut.exe unit-test-std-match.cpp Wed 02/15/2017 0:01:55.04 L:\projects\find\1.0\win>ut 0 0 here is updated test. I wondered if maybe someone got the haystack and needle swapped. no difference. #include <regex> #include <iostream> int main(int argc, char * argv[]) { std::cout<<std::regex_match("def",std::regex("abcdefg",std::regex_constants::extended))<<std::endl; std::cout<<std::regex_match("abcdefg",std::regex("def",std::regex_constants::extended))<<std::endl; return 0; }