error[E0369]: binary operation `+` cannot be applied to type `std::boxed::Box` --> $DIR/autoderef-full-lval.rs:15:24 | LL | let z: isize = a.x + b.y; | --- ^ --- std::boxed::Box | | | std::boxed::Box | = note: an implementation of `std::ops::Add` might be missing for `std::boxed::Box` error[E0369]: binary operation `+` cannot be applied to type `std::boxed::Box` --> $DIR/autoderef-full-lval.rs:21:33 | LL | let answer: isize = forty.a + two.a; | ------- ^ ----- std::boxed::Box | | | std::boxed::Box | = note: an implementation of `std::ops::Add` might be missing for `std::boxed::Box` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0369`.