我收到此错误：
C2664'void Graph_lib :: Widget :: attach（Window＆）'：无法将参数1从'Graph_lib :: Window'转换为'Window＆'
这是一些Window.h代码
namespace Graph_lib {
class Shape; // "forward declare" Shape
class Widget;
class Window : public Fl_Window {
....
和Window.cpp代码，发生错误的地方
namespace Graph_lib {
....
void Window::attach(Widget& w)
{
begin(); // FTLK: begin attaching new Fl_Wigets to this window
**// I got error from this function**
w.attach(*this); // let the Widget create its Fl_Wigits
end(); // FTLK: stop attaching new Fl_Wigets to this window
}
....
和具有Widget类的GUI.h代码
namespace Graph_lib {
....
class Widget {
....
virtual void attach(Window&) = 0;
....
我试图进行强制转换并创建一个变量，但这都是相同的。
Window& win = *this;
Graph_lib::Window& win = *this;
w.attach(static_cast<Window&>(*this));
w.attach(dynamic_cast<Window&>(*this));
我该怎么办？