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// This test checks that we correctly reject the following unsound code.
trait Lengthen<T> {
fn lengthen(self) -> T;
}
impl<'a> Lengthen<&'a str> for &'a str {
fn lengthen(self) -> &'a str { self }
}
trait Gat {
type Gat<'a>: for<'b> Lengthen<Self::Gat<'b>>;
fn lengthen(s: Self::Gat<'_>) -> Self::Gat<'static> {
s.lengthen()
}
}
impl Gat for () {
type Gat<'a> = &'a str; //~ ERROR: implementation of `Lengthen` is not general enough
}
fn main() {
let s = "hello, garbage".to_string();
let borrow: &'static str = <() as Gat>::lengthen(&s);
drop(s);
println!("{borrow}");
}
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