mirror of https://github.com/rust-lang/rust
34 lines
762 B
Rust
34 lines
762 B
Rust
// 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);
|
|
}
|