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