Some crazy macro-abuse I came up with..

... not terribly useful in and of itself, but it allows for an organized extensible systemcall-y/pseudo-dynamic library setup.

#include <stdio.h>

#define BEGIN_FUNC(name, inm, outm) \
       typedef struct name##_in_t { inm }  name##_in; \
       typedef struct name##_out_t { outm }  name##_out; \
       name##_out name(name##_in *in) {name##_out out; printf("l%d %d\n", sizeof(name##_in), sizeof(name##_out));

#define END_FUNC return out;}
#define CALL(output, name, invar ... ) output = name(&(name##_in){invar})
#define CALLA(output, name, invar ... ) name##_out output = name(&(name##_in){invar})

BEGIN_FUNC(test, int a; int ab;, int b;)
       printf("%d %d\n", in->a, in->ab);
       out.b = in->a * 2;
END_FUNC

int main(void)
{
       int x = 2;

       CALLA(outpt, test, 20, x);
       printf("%d\n", outpt.b);
       CALL(outpt, test, 30);
       printf("%d\n", outpt.b);

       return 0;
}