Save view state with id = -1

[BraisGabin]

Why is a view with id 0 a View with no id but a view with id -1 is treated as View with id?

As far as I can see in the documentation View.NO_ID is -1. Even more, reading the source code Android ignores the state of any view with no id:

    protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
        if (mID != NO_ID && (mViewFlags & SAVE_DISABLED_MASK) == 0) {
            // stuff
        }
    }

I'm not sure if this is a bug or I'm missing something...