// run-pass // Uncovered during work on new scoping rules for safe destructors // as an important use case to support properly. pub struct E<'a> { pub f: &'a u8, } impl<'b> E<'b> { pub fn m(&self) -> &'b u8 { self.f } } pub struct P<'c> { pub g: &'c u8, } pub trait M { fn n(&self) -> u8; } impl<'d> M for P<'d> { fn n(&self) -> u8 { *self.g } } fn extension<'e>(x: &'e E<'e>) -> Box { loop { let p = P { g: x.m() }; return Box::new(p) as Box; } } fn main() { let w = E { f: &10 }; let o = extension(&w); assert_eq!(o.n(), 10); }