cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration sys_socket/accept4.c -o sys_socket/accept4 -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
sys_socket/accept4.c:45:18: error: call to undeclared function 'accept4'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   45 |         int server_fd = accept4(listen_fd, (struct sockaddr*) &peer, &peer_len,
      |                         ^
sys_socket/accept4.c:45:18: note: did you mean 'accept'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/socket.h:708:9: note: 'accept' declared here
  708 | int     accept(int, struct sockaddr * __restrict, socklen_t * __restrict)
      |         ^
sys_socket/accept4.c:46:27: error: use of undeclared identifier 'SOCK_CLOEXEC'
   46 |                                  SOCK_CLOEXEC);
      |                                  ^
2 errors generated.