text: /* ISC license. */
  
  #undef _POSIX_C_SOURCE
  #undef _XOPEN_SOURCE
  
  #ifndef _BSD_SOURCE
  #define _BSD_SOURCE
  #endif
  
  #ifndef _GNU_SOURCE
  #define _GNU_SOURCE
  #endif
  
  #ifndef _DEFAULT_SOURCE
  #define _DEFAULT_SOURCE
  #endif
  
  #ifndef _NETBSD_SOURCE
  #define _NETBSD_SOURCE
  #endif
  
  #ifndef __EXTENSIONS__
  #define __EXTENSIONS__
  #endif
  
  #include <sys/types.h>
  #include <unistd.h>
  #include <grp.h>
  
  int main (void)
  {
    gid_t g = 0 ;
    setgroups(1, &g) ;
    return 0 ;
  }
  