error[E0046]: not all trait items implemented, missing: `Output`
  --> $DIR/issue-23827.rs:27:1
   |
LL | impl<C: Component> FnOnce<(C,)> for Prototype {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `Output` in implementation
   |
   = help: implement the missing item: `type Output = /* Type */;`

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0046`.