# Error code E0422

An identifier that is neither defined nor a struct was used.

Erroneous code example:

    fn main () {
        let x = Foo { x: 1, y: 2 };
    }

In this case, `Foo` is undefined, so it inherently isn't anything, and definitely not a struct.

    fn main () {
        let foo = 1;
        let x = foo { x: 1, y: 2 };
    }

In this case, `foo` is defined, but is not a struct, so Rust can't use it as one.