97 string make_error_str(const error_code& ec, string what_arg) {  in make_error_str()  argument
98   if (ec) {  in make_error_str()
102     what_arg += ec.message();  in make_error_str()
107 string make_error_str(const error_code& ec) {  in make_error_str()  argument
108   if (ec) {  in make_error_str()
109     return ec.message();  in make_error_str()
194 system_error::system_error(error_code ec, const string& what_arg)  in system_error()  argument
195     : runtime_error(make_error_str(ec, what_arg)), __ec_(ec) {}  in system_error()
197 system_error::system_error(error_code ec, const char* what_arg)  in system_error()  argument
198     : runtime_error(make_error_str(ec, what_arg)), __ec_(ec) {}  in system_error()
200 system_error::system_error(error_code ec) : runtime_error(make_error_str(ec)), __ec_(ec) {}  in system_error()  argument