rust/src/test/run-pass/resource-cycle.rs

// Don't leak the unique pointers

struct r {
  v: *int,
  drop unsafe {
    debug!("r's dtor: self = %x, self.v = %x, self.v's value = %x",
           unsafe::reinterpret_cast::<*r, uint>(&ptr::addr_of(self)),
           unsafe::reinterpret_cast::<**int, uint>(&ptr::addr_of(self.v)),
           unsafe::reinterpret_cast::<*int, uint>(&self.v));
    let v2: ~int = unsafe::reinterpret_cast(&self.v); }
}

fn r(v: *int) -> r unsafe {
    r {
        v: v
    }
}

enum t = {
    mut next: Option<@t>,
    r: r
};

fn main() unsafe {
    let i1 = ~0;
    let i1p = unsafe::reinterpret_cast(&i1);
    unsafe::forget(i1);
    let i2 = ~0;
    let i2p = unsafe::reinterpret_cast(&i2);
    unsafe::forget(i2);

    let x1 = @t({
        mut next: None,
          r: {
          let rs = r(i1p);
          debug!("r = %x",
                 unsafe::reinterpret_cast::<*r, uint>(&ptr::addr_of(rs)));
          rs }
    });
    
    debug!("x1 = %x, x1.r = %x",
        unsafe::reinterpret_cast::<@t, uint>(&x1),
        unsafe::reinterpret_cast::<*r, uint>(&ptr::addr_of(x1.r)));

    let x2 = @t({
        mut next: None,
          r: {
          let rs = r(i2p);
          debug!("r2 = %x",
                 unsafe::reinterpret_cast::<*r, uint>(&ptr::addr_of(rs)));
          rs
            }
    });
    
    debug!("x2 = %x, x2.r = %x",
           unsafe::reinterpret_cast::<@t, uint>(&x2),
           unsafe::reinterpret_cast::<*r, uint>(&ptr::addr_of(x2.r)));

    x1.next = Some(x2);
    x2.next = Some(x1);
}