struct Struct { person: &'static str } trait Trait { fn f(&self, x: T); } impl Trait<&'static str> for Struct { fn f(&self, x: &'static str) { println!("Hello, {}!", x); } } fn main() { let s: Box> = Box::new(Struct { person: "Fred" }); //~^ ERROR `Struct: Trait` is not satisfied s.f(1); }