clang -O2  -Wall -Wextra -Werror=implicit-function-declaration stdlib/reallocarray.c -o stdlib/reallocarray -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
stdlib/reallocarray.c:16:12: error: implicit declaration of function 'reallocarray' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        numbers = reallocarray(numbers, 16, sizeof(int));
                  ^
stdlib/reallocarray.c:16:12: note: did you mean 'reallocarr'?
/usr/include/stdlib.h:342:5: note: 'reallocarr' declared here
int     reallocarr(void *, size_t, size_t);
        ^
stdlib/reallocarray.c:16:10: warning: incompatible integer to pointer conversion assigning to 'int *' from 'int' [-Wint-conversion]
        numbers = reallocarray(numbers, 16, sizeof(int));
                ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning and 1 error generated.