1 trait A: B + A {}
2 //~^ ERROR cycle detected when computing the super predicates of `A` [E0391]
3 
4 trait B {}
5 
6 impl A for () {}
7 
8 impl B for () {}
9 
main()10 fn main() {
11     let a: Box<dyn A> = Box::new(());
12     let _b: Box<dyn B> = a;
13 }
14