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// run-pass
// Example taken from RFC 1238 text
// https://github.com/rust-lang/rfcs/blob/master/text/1238-nonparametric-dropck.md
// #example-of-the-unguarded-escape-hatch
#![feature(dropck_eyepatch)]
use std::cell::Cell;
struct Concrete<'a>(#[allow(unused_tuple_struct_fields)] u32, Cell<Option<&'a Concrete<'a>>>);
struct Foo<T> { data: Vec<T> }
// Below is the UGEH attribute
unsafe impl<#[may_dangle] T> Drop for Foo<T> {
fn drop(&mut self) { }
}
fn main() {
let mut foo = Foo { data: Vec::new() };
foo.data.push(Concrete(0, Cell::new(None)));
foo.data.push(Concrete(0, Cell::new(None)));
foo.data[0].1.set(Some(&foo.data[1]));
foo.data[1].1.set(Some(&foo.data[0]));
}
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