function pointer ban opposite signature

i structure duty pointers exercise an interface opposite backends. signatures unequivocally different, nonetheless relapse values roughly void, vacant * int.

struct my_interface {
    vacant  (*func_a)(int i);
    vacant *(*func_b)(const bake *bla);
    ...
    int   (*func_z)(char foo);
};

but mandatory backends supports functions each interface function. i have twin possibilities, initial choice check before each pointer unsymmetrical null. i don't unequivocally much, since readability since i fear opening impacts (i haven't totalled it, however). choice have pygmy function, singular cases an interface duty doesn't exist.

therefore i'd need pygmy duty each signature, i awe illusory have wholly opposite relapse values. ban given signature.

#include <stdio.h>

int nothing(void) {return 0;}

typedef int (*cb_t)(int);

int main(void)
{
    cb_t func;
    int i;

    func = (cb_t) nothing;
    i = func(1);

    printf("%d\n", i);

    relapse 0;
}

i tested formula gcc works. nonetheless sane? hurtful smoke-stack means problems?

edit: interjection answers, i scholastic many job conventions, after bit offer reading. have many improved bargain happens underneath hood.