Erroneous code example:
```compile_fail,E0206
-type Foo = [u8; 256];
-impl Copy for Foo { } // error!
-
#[derive(Copy, Clone)]
struct Bar;
impl Copy for &'static mut Bar { } // error!
```
-You can only implement `Copy` for a struct or an enum. Both of the previous
-examples will fail, because neither `[u8; 256]` nor `&'static mut Bar`
-(mutable reference to `Bar`) is a struct or enum.
+You can only implement `Copy` for a struct or an enum.
+The previous example will fail because `&'static mut Bar`
+is not a struct or enum.