error[E0369]: cannot add `Vec<R>` to `Vec<R>`
  --> $DIR/vec-res-add.rs:16:15
   |
LL |     let k = i + j;
   |             - ^ - Vec<R>
   |             |
   |             Vec<R>
   |
note: `Vec<R>` does not implement `Add`
  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
   |
   = note: `Vec<R>` is defined in another crate

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0369`.