cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration unistd/setreuid.c -o unistd/setreuid -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv
unistd/setreuid.c: In function ‘main’:
unistd/setreuid.c:12:14: error: implicit declaration of function ‘setreuid’; did you mean ‘seteuid’? [-Wimplicit-function-declaration]
   12 |         if ( setreuid(ruid, euid) < 0 )
      |              ^~~~~~~~
      |              seteuid