#include <iostream>
using namespace std;
 
class UiControl
{
protected:
    UiControl()
    {
        //The constructor UiControl is private, only objects of subclasses can be created
    }
 
public:
    int x;
    int y;
 
    int width;
    int height;
 
    enum TypeTag { BUTTON, TEXT_FIELD };
    TypeTag typeTag;
};
 
class Button : public UiControl
{
public:
	Button() : UiControl() {}
 
	void foo() {
    auto x = this->typeTag; //Fehler: this->typeTag existiert nicht
	}
};
 
int main() {
	Button b;
	b.foo();
	// your code goes here
	return 0;
}

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