A struct's or struct-like enum variant's field was not provided.

Erroneous code example:

```compile_fail,E0063
struct Foo {
    x: i32,
    y: i32,
}

fn main() {
    let x = Foo { x: 0 }; // error: missing field: `y`
}
```

Each field should be specified exactly once. Example:

```
struct Foo {
    x: i32,
    y: i32,
}

fn main() {
    let x = Foo { x: 0, y: 0 }; // ok!
}
```