Untitled

fn get_mut<'a, 'b, T>(pointer: &'a T) -> &'b mut T {
    unsafe { std::mem::transmute::<*mut T, &mut T>(pointer as *const T as *mut T) }
}

fn write_idx<T: std::fmt::Debug>(vec: &Vec<T>, idx: usize, val: T) {
    unsafe {
    let ptr = get_mut(vec).as_mut_ptr().offset((idx*std::mem::size_of_val(&val)) as isize);
    println!("PTR: {:?}", ptr);
    std::ptr::write(ptr, val);
    }
}

#[derive(Debug)]
struct shit {
    wtf: u64,
}

impl Drop for shit {
    fn drop(&mut self) {
        println!("Dropping shit! {:?}", self);
    }
}

fn blah() {
    let v: Vec<Option<Vec<shit>>> = Vec::with_capacity(1);
    {
        unsafe { get_mut(&v).set_len(1); }
        println!("set_len(&v)");
        let inner_vec: Vec<shit> = Vec::with_capacity(1);
        println!("inner_vec init");
        unsafe { get_mut(&inner_vec).set_len(1); }
        println!("set_len(&inner_vec)");
        write_idx(&inner_vec, 0, shit { wtf: 123 });
        println!("inner_vec[0 = shit");
        write_idx(&v, 0, Some(inner_vec));
        println!("v[0] = inner_vec");
        println!("Added inner vec");
    }
    println!("end of nested block");
    //write_idx(&v, 0, None);
    get_mut(&v)[0] = None;
    println!("V: {:?}", v);
}

fn main() {
    println!("START");
    blah();
    println!("END");

}