1error[E0594]: cannot assign to `self.how_hungry`, which is behind a `&` reference 2 --> $DIR/mutable-class-fields-2.rs:9:5 3 | 4LL | pub fn eat(&self) { 5 | ----- help: consider changing this to be a mutable reference: `&mut self` 6LL | self.how_hungry -= 5; 7 | ^^^^^^^^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written 8 9error: aborting due to previous error 10 11For more information about this error, try `rustc --explain E0594`. 12