clang -O2  -Wall -Wextra -Werror=implicit-function-declaration strings/ffsll.c -o strings/ffsll -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
strings/ffsll.c:11:15: error: implicit declaration of function 'ffsll' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        int output = ffsll(input);
                     ^
strings/ffsll.c:10:15: warning: implicit conversion from 'long long' to 'long' changes value from 67553994410557440 to 0 [-Wconstant-conversion]
        long input = 0xF0000000000000;
             ~~~~~   ^~~~~~~~~~~~~~~~
1 warning and 1 error generated.