error[E0133]: mutation of layout constrained field is unsafe and requires unsafe function or block --> $DIR/ranged_ints2.rs:11:13 | LL | let y = &mut x.0; | ^^^^^^^^ mutation of layout constrained field | = note: mutating layout constrained fields cannot statically be checked for valid values error[E0133]: mutation of layout constrained field is unsafe and requires unsafe function or block --> $DIR/ranged_ints2.rs:12:25 | LL | if let Some(NonZero(ref mut y)) = Some(x) {} | ^^^^^^^^^ mutation of layout constrained field | = note: mutating layout constrained fields cannot statically be checked for valid values error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0133`.