https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45896
--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> --- Another testcase from PR 71556: #include <iostream> #include <sstream> #include <locale> #include <iomanip> int main() { std::tm t = {}; std::istringstream ss("9"); ss.imbue(std::locale("C.UTF-8")); ss >> std::get_time(&t, "%H"); if (ss.fail()) { std::cout << "Parse failed\n"; } else { std::cout << std::put_time(&t, "%c") << '\n'; } }