1error[E0277]: the trait bound `(): Add<A>` is not satisfied
2  --> $DIR/associated-types-ICE-when-projecting-out-of-err.rs:23:11
3   |
4LL |     r = r + a;
5   |           ^ the trait `Add<A>` is not implemented for `()`
6
7error: aborting due to previous error
8
9For more information about this error, try `rustc --explain E0277`.
10