cc -O2 -pipe  -pthread  -Wall -Wextra -Werror -Wno-error=deprecated -Wno-error=deprecated-declarations strings/ffsl.c -o strings/ffsl -D_POSIX_C_SOURCE=202405L  -lm -lpthread 
strings/ffsl.c:11:20: error: use of undeclared identifier 'ffsl'; did you mean 'ffs'?
int (*foo)(long) = ffsl;
                   ^~~~
                   ffs
/usr/include/strings.h:73:6: note: 'ffs' declared here
int      ffs(int);
         ^
strings/ffsl.c:11:7: error: incompatible function pointer types initializing 'int (*)(long)' with an expression of type 'int (int)' [-Werror,-Wincompatible-function-pointer-types]
int (*foo)(long) = ffsl;
      ^            ~~~~
2 errors generated.