rust/src/test/run-pass/issue-979.rs

struct r {
  let b: @mut int;
  drop { *(self.b) += 1; }
}

fn r(b: @mut int) -> r {
    r {
        b: b
    }
}

fn main() {
    let b = @mut 0;
    {
        let p = Some(r(b));
    }

    assert *b == 1;
}