// run-pass // Example taken from RFC 1238 text // https://github.com/rust-lang/rfcs/blob/master/text/1238-nonparametric-dropck.md // #examples-of-code-that-must-continue-to-work use std::cell::Cell; struct Concrete<'a>(#[allow(unused_tuple_struct_fields)] u32, Cell<Option<&'a Concrete<'a>>>); fn main() { let mut data = Vec::new(); data.push(Concrete(0, Cell::new(None))); data.push(Concrete(0, Cell::new(None))); data[0].1.set(Some(&data[1])); data[1].1.set(Some(&data[0])); }