cc -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations pthread/PTHREAD_BARRIER_SERIAL_THREAD.c -o pthread/PTHREAD_BARRIER_SERIAL_THREAD -D_POSIX_C_SOURCE=202405L  -lm -lpthread  -liconv
pthread/PTHREAD_BARRIER_SERIAL_THREAD.c:2:17: error: use of undeclared identifier 'PTHREAD_BARRIER_SERIAL_THREAD'
    2 | int const foo = PTHREAD_BARRIER_SERIAL_THREAD;
      |                 ^
1 error generated.