#prog #rust #suckassstory

github.com/rust-lang/rust/issues/164250

use std::sync::Mutex;
static KEPT: Mutex<Vec<Box<dyn std::any::Any + Send>>> =
    Mutex::new(Vec::new());

struct Q<T: 'static + Send>(Option<T>);

impl<T: 'static + Send> Drop for Q<T> {
    fn drop(&mut self) {
        if let Some(t) = self.0.take() {
            KEPT.lock().unwrap().push(Box::new(t));
        }
    }
}

fn main() {
    {
        let l = String::from("hello world, this is long enough");
        let mut q = Q(None);
        q.0 = Some(&l);
    }
    let _z = String::from("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
    let k = KEPT.lock().unwrap();
    println!("{}", k[0].downcast_ref::<&'static String>().unwrap());
}

I expected to see this happen: program is not accepted
Instead, this happened: program compiles and prints XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX. With asan, the program will crash with a AddressSanitizer: stack-use-after-scope