How do I sum two integers in C?

subject.

SMUG C++ WEENIE quality:
#include <stdlib.h>
#include <stdarg.h>

typedef struct CContainer_VTable_s {
    void *(*foldr)(void*, void*, void *(*)(void*, void*));
    void *(*foldr1)(void*, void *(*)(void*, void*));
    int (*count)(void*);
} CContainer_VTable;

typedef struct CContainer_s {
    CContainer_VTable *vtable;
} CContainer;

#define DEFLL(t) \
struct LinkedList_s$##t { \
    CContainer super; \
    t value; \
    struct LinkedList_s$##t *next; \
}; \
typedef struct LinkedList_s$##t LinkedList$##t; \
\
CContainer_VTable VTABLE_LinkedList$##t; \
\
int LinkedList$##t_count(void *p) \
{ \
    LinkedList$##t *w = p; \
    return w ? 1 + LinkedList$##t_count(w->next) : 0; \
} \
\
void *LinkedList$##t_foldr(void *p, void *z, void *(*f)(void*, void*)) \
{ \
    LinkedList$##t *w = p; \
    return w ? (*f)(&w->value, LinkedList$##t_foldr(w->next, z, f)) : z; \
} \
void *LinkedList$##t_foldr1(void *p, void *(*f)(void*, void*)) \
{ \
    LinkedList$##t *w = p; \
    return LinkedList$##t_foldr(w->next, &w->value, f); \
} \
\
LinkedList$##t *vnew_LinkedList$##t(int count, va_list args) \
{ \
    LinkedList$##t *w = NULL; \
    if (count) \
    { \
        w = malloc(sizeof(LinkedList$##t)); \
        w->super.vtable = &VTABLE_LinkedList$##t; \
        w->value = va_arg(args, t); \
        w->next = vnew_LinkedList$##t(count - 1, args); \
    } \
    return w; \
} \
LinkedList$##t *new_LinkedList$##t(int count, ...) \
{ \
    va_list args; \
    LinkedList$##t *w = NULL; \
    va_start(args, count); \
    w = vnew_LinkedList$##t(count, args); \
    va_end(args); \
    return w; \
} \
void delete_LinkedList$##t(LinkedList$##t *w) \
{ \
    if (w) \
    { \
        delete_LinkedList$##t(w->next); \
        free(w); \
    } \
}

#define INITLL(t) do { \
VTABLE_LinkedList$##t.foldr = &LinkedList$##t_foldr; \
VTABLE_LinkedList$##t.foldr1 = &LinkedList$##t_foldr1; \
VTABLE_LinkedList$##t.count = &LinkedList$##t_count; \
} while (0)

#define LL(t) LinkedList$##t
#define NEWLL(t) new_LinkedList$##t
#define DELETELL(t) delete_LinkedList$##t

DEFLL(int);

void *add(void *p, void *q)
{
    int *a = p, *b = q, *r = malloc(sizeof(int));
    *r = *a + *b;
    return r;
}

int sum(int a, int b)
{
    int *r;
    LL(int) *l = NEWLL(int)(2, a, b);
    r = l->super.vtable->foldr1(l, &add);
    DELETELL(int)(l);
    return *r;
}

Note that you have to call INITLL(int); somewhere before calling NEWLL(int)(...);. Implementing an add which doesn't leak memory is left as an exercise to the reader.