CHECK_CXX_SOURCE_RUNS("
    #include<stdlib.h>
    #include<time.h>
    int main(int, char *[]) {
      setenv(\"TZ\", \"America/Los_Angeles\", 1);
      tzset();
      struct tm time2037;
      struct tm time2038;
      strptime(\"2037-05-05 12:34:56\", \"%Y-%m-%d %H:%M:%S\", &time2037);
      strptime(\"2038-05-05 12:34:56\", \"%Y-%m-%d %H:%M:%S\", &time2038);
      return mktime(&time2038) - mktime(&time2037) != 31536000;
    }"
  HAS_POST_2038
)