1 error[E0368]: binary assignment operation `+=` cannot be applied to type `Foo`
2 --> $DIR/assignment-operator-unimplemented.rs:6:3
7 | cannot use `+=` on type `Foo`
9 note: an implementation of `AddAssign<_>` might be missing for `Foo`
10 --> $DIR/assignment-operator-unimplemented.rs:1:1
13 | ^^^^^^^^^^^ must implement `AddAssign<_>`
14 note: the following trait must be implemented
15 --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
17 LL | / pub trait AddAssign<Rhs = Self> {
18 LL | | /// Performs the `+=` operation.
22 LL | | fn add_assign(&mut self, rhs: Rhs);
26 error: aborting due to previous error
28 For more information about this error, try `rustc --explain E0368`.