error[E0133]: borrow of layout constrained field with interior mutability is unsafe and requires unsafe function or block --> $DIR/ranged_ints3.rs:10:13 | LL | let y = &x.0; | ^^^^ borrow of layout constrained field with interior mutability | = note: references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0133`.