Rust error E0639: this error indicates that the struct, enum or enum variant cannot be instantiated from outside of the defining crate as it has been marked as `non_exhaustive` and as such more fields/variants may be added in future that could cause adverse side effects for this code

The compiler team's explanation

This error indicates that the struct, enum or enum variant cannot be instantiated from outside of the defining crate as it has been marked as non_exhaustive and as such more fields/variants may be added in future that could cause adverse side effects for this code.

Erroneous code example:

#[non_exhaustive]
pub struct NormalStruct {
    pub first_field: u16,
    pub second_field: u16,
}

let ns = NormalStruct { first_field: 640, second_field: 480 }; // error!

It is recommended that you look for a new function or equivalent in the crate's documentation.

From rustc --explain E0639 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.