Corretade way to extend a component

[insdo]

Hello. I tried to create an inherited component of QLineEdit class. But it is giving error: undefined symbol Link2019 external. I do not know what can be. For I have put my diretrize "include".
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#ifndef MEUCAMPO_H
#define MEUCAMPO_H

#include <QLineEdit>
 
class MeuCampo : public QLineEdit
{
    Q_OBJECT
public:
    explicit MeuCampo(QWidget *parent = 0);
 
signals:
 
public slots:
 
};
 
#endif // MEUCAMPO_H
 
#include "meucampo.h"
 
MeuCampo::MeuCampo(QWidget *parent) :
    QLineEdit(parent)
{
}

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