/opt/IBM/openxlC/17.1.1/bin/ibm-clang -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations mqueue/O_RDWR.c -o mqueue/O_RDWR -D_POSIX_C_SOURCE=202405L -lm -lpthread -lrt -latomic
mqueue/O_RDWR.c:4:2: error: "O_RDWR is not defined"
#error "O_RDWR is not defined"
 ^
1 error generated.