error[E0391]: cycle detected when computing whether `<impl at $DIR/impl-wf-cycle-4.rs:5:1: 7:26>` has a guaranteed unsized self type
  --> $DIR/impl-wf-cycle-4.rs:5:1
   |
LL | / impl<T> Filter for T
LL | | where
LL | |     T: Fn(Self::ToMatch),
   | |_________________________^
   |
note: ...which requires computing normalized predicates of `<impl at $DIR/impl-wf-cycle-4.rs:5:1: 7:26>`...
  --> $DIR/impl-wf-cycle-4.rs:5:1
   |
LL | / impl<T> Filter for T
LL | | where
LL | |     T: Fn(Self::ToMatch),
   | |_________________________^
   = note: ...which again requires computing whether `<impl at $DIR/impl-wf-cycle-4.rs:5:1: 7:26>` has a guaranteed unsized self type, completing the cycle
note: cycle used when checking that `<impl at $DIR/impl-wf-cycle-4.rs:5:1: 7:26>` is well-formed
  --> $DIR/impl-wf-cycle-4.rs:5:1
   |
LL | / impl<T> Filter for T
LL | | where
LL | |     T: Fn(Self::ToMatch),
   | |_________________________^
   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information

error: aborting due to 1 previous error

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