src/test/ui/cycle-trait/cycle-trait-default-type-trait.stderr

error[E0391]: cycle detected when processing `Foo::X`
  --> $DIR/cycle-trait-default-type-trait.rs:4:19
   |
LL | trait Foo<X = Box<Foo>> {
   |                   ^^^
   |
   = note: ...which again requires processing `Foo::X`, completing the cycle

error: aborting due to previous error

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