Qt forbid declaration of QListView with no type

Question

I have a very strange error in my Qt project. Here is the code, the main_window.h:

#include <QtGui>
#include <QtSql>

class main_window : public QTabWidget
{
    Q_OBJECT

    /// @name List Widgets
private:
    QListWidget*    m_documents_list;
....

and here is main_window.cpp:

...
void main_window::create_documents_widget()
{
    m_documents = new QWidget(this);
    m_documents_list = new QListWidget(m_documents);
}
...

The problem that I can't understand is in QListView, I'm not using it in my project. There is only QListWidget, but when I'm trying to build the project the following errors occur:

qlistview.h:194: error: ISO C++ forbids declaration of 'QListView' with no type

qlistview.h:194: error: expected ',' or '...' before '&' token

Also the following strange errors:

qlistwidget.h:308: error: no 'void QListWidget::removeItemWidget(QListWidgetItem)' member function declared in class 'QListWidget'*

qlistwidget.h:311: error: no 'void QListWidget::addItem(QListWidgetItem)' member function declared in class 'QListWidget'*

qlistwidget.h:314: error: no 'QListWidgetItem QListWidget::itemAt(int, int) const' member function declared in class 'QListWidget'*

etc.

Thanks in advance.

UPD: I'm using QtCreator 2.2.1 on Windows 7.

UPD2: Qt version is 4.7.1.

UPD3: The complete output

In file included from c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/QtGui:68,
                 from ..\my_project\/main_window.h:4,
                 from ..\my_project\main.cpp:2:
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistview.h:194: error: ISO C++ forbids declaration of 'QListView' with no type
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistview.h:194: error: expected ',' or '...' before '&' token
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistview.h:194: error: ISO C++ forbids declaration of 'QListView' with no type
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistview.h:194: error: ISO C++ forbids declaration of 'QListView' with no type
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistview.h:194: error: expected ';' before '&' token
In file included from c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/QtGui:69,
                 from ..\my_project\/main_window.h:4,
                 from ..\my_project\main.cpp:2:
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:202: error: redefinition of 'class QListWidget'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistview.h:58: error: previous definition of 'class QListWidget'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:308: error: no 'void QListWidget::removeItemWidget(QListWidgetItem*)' member function declared in class 'QListWidget'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:311: error: no 'void QListWidget::addItem(QListWidgetItem*)' member function declared in class 'QListWidget'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:314: error: no 'QListWidgetItem* QListWidget::itemAt(int, int) const' member function declared in class 'QListWidget'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h: In member function 'void QListWidgetItem::setSelected(bool)':
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:318: error: 'class QListWidget' has no member named 'setItemSelected'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h: In member function 'bool QListWidgetItem::isSelected() const':
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:321: error: 'class QListWidget' has no member named 'isItemSelected'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h: In member function 'void QListWidgetItem::setHidden(bool)':
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:324: error: 'class QListWidget' has no member named 'setItemHidden'
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h: In member function 'bool QListWidgetItem::isHidden() const':
c:\QtSDK\Desktop\Qt\4.7.3\mingw\include\QtGui/qlistwidget.h:327: error: 'class QListWidget' has no member named 'isItemHidden'

Answer 1

Firstly - you should also mention qt version, as in this case that's most important.

This seems like some weird quirk of compiler or qt - my recomendation would be first to create simplest program where problem occurs. If it shows also in program like

#include <QtGui/QListWidget>
int main(int argc, char* argv[]){
    QListWidget* w = 0;
}

then it is some problem with qt headers of compiler - then answer cannot be provided from data provided. If it works, then try to slowly add other elements of your code to this simple file - most likely at some point you will get the same error again - then you will know that last added piece of code is guilty. Some additional thinking might be required to figure out how to remove problem once located.

Answer 2

It should be noted that QListWidget inherits from QListView, so you are indirectly using it.

The error your getting looks like you're simply missing a #include <QListWidget> line in your header file.

Also, it could be that that you're missing #include guards in your header file

#ifndef MYCLASS
#define MYCLASS

class MyClass { ... };

#endif

If your header file is #included by more than one project then that would explain the errors you're seeing.