Erroneous code example:
```compile_fail,E0567
-#![feature(optin_builtin_traits)]
+#![feature(auto_traits)]
auto trait Generic<T> {} // error!
# fn main() {}
To fix this issue, just remove the generics:
```
-#![feature(optin_builtin_traits)]
+#![feature(auto_traits)]
auto trait Generic {} // ok!
# fn main() {}