Error: arithmetic on a pointer to void

Void pointer artihmetic throws an error: 
```cpp
void *cpy(void *dest, const void *src, size_t n);
static bool exec(void *buf, size_t size, void *info, size_t size2) {
    memcpy(buf + size * size2++, info, size);
    return true;
}
```
ClangSharpPInvokeGenerator: 
```
Diagnostics for '.\test.h':
    .\test.h:12:25: error: arithmetic on a pointer to void
```