error[E0391]: cycle detected when computing the super traits of `Processor` with associated type name `Input`
  --> $DIR/issue-20825.rs:5:1
   |
LL | pub trait Processor: Subscriber<Input = Self::Input> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: ...which immediately requires computing the super traits of `Processor` with associated type name `Input` again
note: cycle used when computing the super traits of `Processor`
  --> $DIR/issue-20825.rs:5:1
   |
LL | pub trait Processor: Subscriber<Input = Self::Input> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0391`.
