/opt/IBM/openxlC/17.1.1/bin/ibm-clang -pthread  -Wall -Wextra -Werror=implicit-function-declaration unistd/getentropy.c -o unistd/getentropy -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -latomic
unistd/getentropy.c:15:7: error: call to undeclared function 'getentropy'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
        if ( getentropy(buf, sizeof(buf)) < 0 )
             ^
1 error generated.