.AsSpan阵列类型不匹配异常

斯梅博迪能解释为什么吗。当创建新的ReadOnlySpan时,AsSpan Throws一个ArrayTypeMismatchException没有?

SomeMethod(Foo data) {
  IPoint[] tmp = (IPoint[])data.Points; // data.Points is OwnPoint[] (class OwnPoint : IPoint)
  //ReadOnlySpan<IPoint> pointsSpan = ((IPoint[])tmp).AsSpan(); //  System.ArrayTypeMismatchException: 'Attempted to access an element as a type incompatible with the array.'
  //ReadOnlySpan<IPoint> pointsSpan = tmp.AsSpan(); //  System.ArrayTypeMismatchException: 'Attempted to access an element as a type incompatible with the array.'
  ReadOnlySpan<IPoint> pointsSpan = new ReadOnlySpan<IPoint>(tmp);// works
  Bar(pointsSpan);
}

public void Bar(ReadOnlySpan<IPoint> pts) {
    // ...
}