protocol P {
      associatedtype PType
  }

  public protocol Q {
      associatedtype QType: R
  }

  public protocol R {
      associatedtype RType
  }

  func f<T: P>(_: T) where T.PType.RType: Q, T.PType.RType.QType == T.PType {}

// We get this signature: <T where T : P, T.PType : R, T.PType == T.PType.RType.QType, T.PType.RType : Q>

// But we should get this signature: <T where T : P, T.PType == T.PType.RType.QType, T.PType.RType : Q>

// The “T.PType: R” requirement is redundant, but pops up when building the canonical generic environment due to the recursion-breaking code being wrong.