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 trait `AddAssign` must be implemented
15 --> $SRC_DIR/core/src/ops/arith.rs:LL:COL
17 error: aborting due to previous error
19 For more information about this error, try `rustc --explain E0368`.