A good implementation of GetHashCode in C#

HashCode.cs

V val; // struct
T obj; // class
V? nlv; // Nullable
X unk; // not known if class or struct
public override int GetHashCode() {
  int h = 23;
  unchecked {
    h = (h << 5) - h + val.GetHashCode();
    h = (h << 5) - h + (obj != null ? obj.GetHashCode() : 0);
    h = (h << 5) - h + (nlv != null ? nlv.GetHashCode() : int.MinValue);
    h = (h << 5) - h + (unk is System.ValueType || (object)unk != null ? unk.GetHashCode() : 0);
  }
  return h;
}