C version of strange ooc generics bug

c_version.c

#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>

typedef struct {
    int min;
    int max;
} Range;

void slice(uint8_t* genReturn, uint8_t* data, Range range) {
    int size = range.max - range.min;
    uint8_t* ret = ((uint8_t*) (malloc(size * 4)));
    
    {
        int i;
        for (i = 0; i < size; i++) {
            memcpy(&(ret[i * 4]), &(data[(range.min + i) * 4]), 4);
        }
    }
    if (genReturn) {
        genReturn = ret;
    }
    return;
}

int* list;
int* data;
void main() {
    list = ((int*) ((int[]) { 0, 1, 2, 3, 4 }));
    if(!data) printf("OK D:\n"); // This is printed, this is the problem <--- genReturn != NULL is false so genReturn is never set to ret ;)
    slice((uint8_t*) data, (uint8_t*) list, (Range) { 0, 3 });
    if (!data) {
        printf("Dafuq!\n");
    }
}