use std::cell::Cell; // const qualification is not smart enough to know about fields and always assumes that there might // be other fields that caused the qualification const FOO: &Option> = { let mut a = (Some(Cell::new(0)),); a.0 = None; // sets `qualif(a)` to `qualif(a) | qualif(None)` &{a.0} //~ ERROR cannot refer to interior mutable }; fn main() {}