| // Taken from https://github.com/rust-lang/rust/issues/44454#issuecomment-1332781290 |
| |
| use std::any::Any; |
| |
| trait Animal<X>: 'static {} |
| |
| trait Projector { |
| type Foo; |
| } |
| |
| impl<X> Projector for dyn Animal<X> { |
| type Foo = X; |
| } |
| |
| fn make_static<'a, T>(t: &'a T) -> &'static T { |
| let x: <dyn Animal<&'a T> as Projector>::Foo = t; |
| let any = generic::<dyn Animal<&'a T>, &'a T>(x); |
| //~^ ERROR: lifetime may not live long enough |
| any.downcast_ref::<&'static T>().unwrap() |
| } |
| |
| fn generic<T: Projector + Animal<U> + ?Sized, U>(x: <T as Projector>::Foo) -> Box<dyn Any> { |
| make_static_any(x) |
| } |
| |
| fn make_static_any<U: 'static>(u: U) -> Box<dyn Any> { |
| Box::new(u) |
| } |
| |
| fn main() { |
| let a = make_static(&"salut".to_string()); |
| println!("{}", *a); |
| } |