| // compile-flags: -Ztrait-solver=next |
| #![feature(rustc_attrs, trivial_bounds)] |
| |
| // We have to be careful here: |
| // |
| // We either have the provisional result of `A -> B -> A` on the |
| // stack, which is a fully coinductive cycle. Accessing the |
| // provisional result for `B` as part of the `A -> C -> B -> A` cycle |
| // has to make sure we don't just use the result of `A -> B -> A` as the |
| // new cycle is inductive. |
| // |
| // Alternatively, if we have `A -> C -> A` first, then `A -> B -> A` has |
| // a purely inductive stack, so something could also go wrong here. |
| |
| #[rustc_coinductive] |
| trait A {} |
| #[rustc_coinductive] |
| trait B {} |
| trait C {} |
| |
| impl<T: B + C> A for T {} |
| impl<T: A> B for T {} |
| impl<T: B> C for T {} |
| |
| fn impls_a<T: A>() {} |
| |
| // The same test with reordered where clauses to make sure we're actually testing anything. |
| #[rustc_coinductive] |
| trait AR {} |
| #[rustc_coinductive] |
| trait BR {} |
| trait CR {} |
| |
| impl<T: CR + BR> AR for T {} |
| impl<T: AR> BR for T {} |
| impl<T: BR> CR for T {} |
| |
| fn impls_ar<T: AR>() {} |
| |
| fn main() { |
| impls_a::<()>(); |
| //~^ ERROR overflow evaluating the requirement `(): A` |
| |
| impls_ar::<()>(); |
| //~^ ERROR overflow evaluating the requirement `(): AR` |
| } |
