error[E0368]: binary assignment operation `+=` cannot be applied to type `Foo` --> $DIR/assignment-operator-unimplemented.rs:6:3 | LL | a += *b; | -^^^^^^ | | | cannot use `+=` on type `Foo` | = note: an implementation of `std::ops::AddAssign` might be missing for `Foo` error: aborting due to previous error For more information about this error, try `rustc --explain E0368`.