clang -O2  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations sys_socket/accept4.c -o sys_socket/accept4 -D_POSIX_C_SOURCE=202405L  -lm  -lintl
sys_socket/accept4.c:5:72: error: use of undeclared identifier 'accept4'; did you mean 'accept'?
int (*foo)(int, struct sockaddr *restrict, socklen_t *restrict, int) = accept4;
                                                                       ^~~~~~~
                                                                       accept
/usr/include/sys/socket.h:636:5: note: 'accept' declared here
int     accept(int, struct sockaddr * __restrict, socklen_t * __restrict);
        ^
sys_socket/accept4.c:5:7: error: incompatible pointer types initializing 'int (*)(int, struct sockaddr *restrict, __socklen_t *restrict, int)' with an expression of type 'int (int, struct sockaddr *restrict, __socklen_t *restrict)' [-Werror,-Wincompatible-pointer-types]
int (*foo)(int, struct sockaddr *restrict, socklen_t *restrict, int) = accept4;
      ^                                                                ~~~~~~~
2 errors generated.