Attempted to access a field on a primitive type. Erroneous code example: ```compile_fail,E0610 let x: u32 = 0; println!("{}", x.foo); // error: `{integer}` is a primitive type, therefore // doesn't have fields ``` Primitive types are the most basic types available in Rust and don't have fields. To access data via named fields, struct types are used. Example: ``` // We declare struct called `Foo` containing two fields: struct Foo { x: u32, y: i64, } // We create an instance of this struct: let variable = Foo { x: 0, y: -12 }; // And we can now access its fields: println!("x: {}, y: {}", variable.x, variable.y); ``` For more information about [primitives] and [structs], take a look at the Book. [primitives]: https://doc.rust-lang.org/book/ch03-02-data-types.html [structs]: https://doc.rust-lang.org/book/ch05-00-structs.html