class Bug854
{
  public Foo[T](x : T) : void where T : T { // E: A constraint of 'T' type parameter is cyclic \(T => T\)
    _ = x.Foo()
  }
}

public class X[A, // E: A constraint of 'A' type parameter is cyclic \(A => B => C => A\)
  B, C, D, E] 
  
  where A: B
  where B: C
  where C: A
  where D: E
{
}

class A : B {} // E: type definition for `A' is cyclic
class B : A {}

class C : C.I { // E: type definition for `C' is cyclic
  interface I {
  }
}