| A non-structural-match type was used as the type of a const generic parameter. |
| |
| Erroneous code example: |
| |
| ```compile_fail,E0741 |
| #![feature(adt_const_params)] |
| |
| struct A; |
| |
| struct B<const X: A>; // error! |
| ``` |
| |
| Only structural-match types (that is, types that derive `PartialEq` and `Eq`) |
| may be used as the types of const generic parameters. |
| |
| To fix the previous code example, we derive `PartialEq` and `Eq`: |
| |
| ``` |
| #![feature(adt_const_params)] |
| |
| #[derive(PartialEq, Eq)] // We derive both traits here. |
| struct A; |
| |
| struct B<const X: A>; // ok! |
| ``` |
