| Only `structural_match` types (that is, types that derive `PartialEq` and `Eq`) | |
| may be used as the types of const generic parameters. | |
| ```compile_fail,E0741 | |
| #![feature(const_generics)] | |
| struct A; | |
| struct B<const X: A>; // error! | |
| ``` | |
| To fix this example, we derive `PartialEq` and `Eq`. | |
| ``` | |
| #![feature(const_generics)] | |
| #[derive(PartialEq, Eq)] | |
| struct A; | |
| struct B<const X: A>; // ok! | |
| ``` |