#![allow(warnings)] trait A<T> { } struct B<'a, T:'a>(&'a (A<T>+'a)); trait X { } impl<'a, T> X for B<'a, T> {} fn h<'a, T, U:'static>(v: Box<A<U>+'static>) -> Box<X+'static> { Box::new(B(&*v)) as Box<X> //~ ERROR cannot return value referencing local data `*v` } fn main() {}