cc -pthread  -Wall -Wextra -Werror=implicit-function-declaration unistd/pipe2.c -o unistd/pipe2 -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm -lpthread  -liconv
unistd/pipe2.c:11:7: error: call to undeclared function 'pipe2'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
   11 |         if ( pipe2(fds, O_CLOEXEC) < 0 )
      |              ^
unistd/pipe2.c:11:7: note: did you mean 'pipe'?
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/unistd.h:474:6: note: 'pipe' declared here
  474 | int      pipe(int [2]);
      |          ^
1 error generated.