Something other than a struct, variant or union has been used when one was
expected.

Erroneous code example:

```compile_fail,E0574
mod mordor {}

let sauron = mordor { x: () }; // error!

enum Jak {
    Daxter { i: isize },
}

let eco = Jak::Daxter { i: 1 };
match eco {
    Jak { i } => {} // error!
}
```

In all these errors, a type was expected. For example, in the first error,
we tried to instantiate the `mordor` module, which is impossible. If you want
to instantiate a type inside a module, you can do it as follow:

```
mod mordor {
    pub struct TheRing {
        pub x: usize,
    }
}

let sauron = mordor::TheRing { x: 1 }; // ok!
```

In the second error, we tried to bind the `Jak` enum directly, which is not
possible: you can only bind one of its variants. To do so:

```
enum Jak {
    Daxter { i: isize },
}

let eco = Jak::Daxter { i: 1 };
match eco {
    Jak::Daxter { i } => {} // ok!
}
```