invalid application of 'sizeof' to incomplete type 'QVariant'

Elnur_Ismailzada

Hi!
I want to fill the combo box in qml from c++ class, but I have errors in the line return m_serialPortList;
Any ideas?

in SerialPortViewModel.h

Q_PROPERTY(QVariantList serialPortList READ getSerialPortList CONSTANT)

public:
    QVariantList getSerialPortList();
private:
    QVariantList m_serialPortList;

in SerialPortViewModel.cpp

QVariantList SerialPortViewModel::getSerialPortList()
{
    return m_serialPortList;
}

in main.cpp

engine.rootContext()->setContextProperty("model", new SerialPortViewModel());

in main.qml

ComboBox {
         id: comboBoxSerialPorts
         model: model.serialPortList
}

error:

In file included from C:\Qt\5.9.1\mingw53_32\include/QtCore/qglobal.h:1152:0,
                 from C:\Qt\5.9.1\mingw53_32\include/QtCore/qnamespace.h:43,
                 from C:\Qt\5.9.1\mingw53_32\include/QtCore/qobjectdefs.h:48,
                 from C:\Qt\5.9.1\mingw53_32\include\QtCore/qobject.h:46,
                 from C:\Qt\5.9.1\mingw53_32\include\QtCore/QObject:1,
                 from ..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.h:4,
                 from ..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.cpp:1:
C:\Qt\5.9.1\mingw53_32\include/QtCore/qtypeinfo.h: In instantiation of 'class QTypeInfo<QVariant>':
C:\Qt\5.9.1\mingw53_32\include/QtCore/qlist.h:459:31:   required from 'void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = QVariant]'
C:\Qt\5.9.1\mingw53_32\include/QtCore/qlist.h:813:22:   required from 'QList<T>::QList(const QList<T>&) [with T = QVariant]'
..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.cpp:5:12:   required from here
C:\Qt\5.9.1\mingw53_32\include/QtCore/qtypeinfo.h:67:26: error: invalid application of 'sizeof' to incomplete type 'QVariant'
         isLarge = (sizeof(T)>sizeof(void*)),
                          ^
C:\Qt\5.9.1\mingw53_32\include/QtCore/qtypeinfo.h:69:24: error: invalid application of 'sizeof' to incomplete type 'QVariant'
         sizeOf = sizeof(T)
                        ^
In file included from C:\Qt\5.9.1\mingw53_32\include\QtCore/qobject.h:49:0,
                 from C:\Qt\5.9.1\mingw53_32\include\QtCore/QObject:1,
                 from ..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.h:4,
                 from ..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.cpp:1:
C:\Qt\5.9.1\mingw53_32\include/QtCore/qlist.h: In instantiation of 'void QList<T>::node_copy(QList<T>::Node*, QList<T>::Node*, QList<T>::Node*) [with T = QVariant]':
C:\Qt\5.9.1\mingw53_32\include/QtCore/qlist.h:813:22:   required from 'QList<T>::QList(const QList<T>&) [with T = QVariant]'
..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.cpp:5:12:   required from here
C:\Qt\5.9.1\mingw53_32\include/QtCore/qlist.h:462:28: error: invalid use of incomplete type 'class QVariant'
                 current->v = new T(*reinterpret_cast<T*>(src->v));
                            ^
In file included from C:\Qt\5.9.1\mingw53_32\include\QtCore/qobject.h:54:0,
                 from C:\Qt\5.9.1\mingw53_32\include\QtCore/QObject:1,
                 from ..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.h:4,
                 from ..\..\HidBallast-QtQuick MVVM\HidBallast\serialportviewmodel.cpp:1:
C:\Qt\5.9.1\mingw53_32\include/QtCore/qmetatype.h:114:21: note: forward declaration of 'class QVariant'
     F(QVariant, 41, QVariant) \
                     ^
C:\Qt\5.9.1\mingw53_32\include/QtCore/qmetatype.h:1879:11: note: in definition of macro 'QT_FORWARD_DECLARE_STATIC_TYPES_ITER'
     class Name;
           ^
C:\Qt\5.9.1\mingw53_32\include/QtCore/qmetatype.h:1881:1: note: in expansion of macro 'QT_FOR_EACH_STATIC_CORE_CLASS'
 QT_FOR_EACH_STATIC_CORE_CLASS(QT_FORWARD_DECLARE_STATIC_TYPES_ITER)

hskoglund

Hi, try #include <QVariant> in your SerialPortViewModel.h

Elnur_Ismailzada

@hskoglund thank you so much!!!
I import <QVarianList> and it solved my problem.