mirror of https://github.com/rust-lang/rust
32 lines
844 B
Rust
32 lines
844 B
Rust
#![feature(type_alias_impl_trait)]
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trait Static: 'static {}
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impl Static for () {}
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type Gal<T> = impl Static;
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fn _defining<T>() -> Gal<T> {}
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trait Callable<Arg> { type Output; }
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/// We can infer `<C as Callable<Arg>>::Output: 'static`,
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/// because we know `C: 'static` and `Arg: 'static`,
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fn box_str<C, Arg>(s: C::Output) -> Box<dyn AsRef<str> + 'static>
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where
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Arg: Static,
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C: ?Sized + Callable<Arg> + 'static,
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C::Output: AsRef<str>,
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{
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Box::new(s)
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}
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fn extend_lifetime(s: &str) -> Box<dyn AsRef<str> + 'static> {
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type MalformedTy = dyn for<'a> Callable<Gal<&'a ()>, Output = &'a str>;
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//~^ ERROR binding for associated type `Output` references lifetime `'a`
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box_str::<MalformedTy, _>(s)
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}
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fn main() {
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let extended = extend_lifetime(&String::from("hello"));
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println!("{}", extended.as_ref().as_ref());
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}
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