error[E0275]: overflow evaluating the requirement `{integer}: Tweedledee`
  --> $DIR/simultaneous.rs:18:5
   |
LL | fn is_ee<T: Combo>(t: T) {
   |             ----- required by this bound in `is_ee`
...
LL |     is_ee(4);
   |     ^^^^^
   |
note: required because of the requirements on the impl of `Combo` for `{integer}`
  --> $DIR/simultaneous.rs:11:34
   |
LL | impl<T: Tweedledee + Tweedledum> Combo for T {}
   |                                  ^^^^^     ^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0275`.