[solved] Getting error "duplicate symbol: findNext" when there seems to be no duplication

[bmahf]

Hi all,

I am just starting to use Qt (ok, I looked at it before for a short time, but now I'm back) and I'm trying to compile a simple program, but I'm getting duplicate symbol where there seems to be no duplicates. I'm actually following along in the book "C++ GUI Programming with Qt 4: Second Edition" by Blanchette & Summerfield. Starting on page 13, then talk about creating dialogs, so I created the files they said I should and now I'm getting this error. I have created a new project with the minimum number of lines to still get this error. To do so, I created a new gui application called TestMe, and removed the MainWindow class and header files from the project. I then added a FindDialog class to the project and defined them as such:

@
-----------------main.cpp----------------------
#include <QtGui/QApplication>
#include "finddialog.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

FindDialog *dialog = new FindDialog;
dialog->show();

return a.exec();

}
--------------end main.cpp---------------------

--------------finddialog.h-----------------------
#ifndef FINDDIALOG_H
#define FINDDIALOG_H

#include <QDialog>

class FindDialog : QDialog
{
Q_OBJECT

public:
FindDialog(QWidget *parent = 0);

signals:
void findNext(const QString &str, Qt::CaseSensitivity cs);

};

#endif // FINDDIALOG_H

-----------end finddialog.h----------------------

-----------finddialog.cpp------------------------
#include "finddialog.h"

FindDialog::FindDialog(QWidget *parent)
: QDialog(parent)
{
}

void FindDialog::findNext(const QString &str, Qt::CaseSensitivity cs)
{
}

---------end finddialog.cpp----------------------
@

The error I'm getting from a fresh creation of this small project is:

Running build steps for project TestMe...
Configuration unchanged, skipping qmake step.
Starting: "/usr/bin/make" -w
make: Entering directory /Users/bruce/Projects/Qt Projects/TestMe-build-desktop' g++ -c -pipe -g -gdwarf-2 -arch i386 -Wall -W -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/Qt4.6/mkspecs/macx-g++ -I../TestMe -I/Library/Frameworks/QtCore.framework/Versions/4/Headers -I/usr/include/QtCore -I/Library/Frameworks/QtGui.framework/Versions/4/Headers -I/usr/include/QtGui -I/usr/include -I. -I../TestMe -I. -F/Library/Frameworks -o finddialog.o ../TestMe/finddialog.cpp ../TestMe/finddialog.cpp:8: warning: unused parameter 'str' ../TestMe/finddialog.cpp:8: warning: unused parameter 'cs' /Developer/Tools/Qt/moc -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/Qt4.6/mkspecs/macx-g++ -I../TestMe -I/Library/Frameworks/QtCore.framework/Versions/4/Headers -I/usr/include/QtCore -I/Library/Frameworks/QtGui.framework/Versions/4/Headers -I/usr/include/QtGui -I/usr/include -I. -I../TestMe -I. -F/Library/Frameworks -D__APPLE__ -D__GNUC__ ../TestMe/finddialog.h -o moc_finddialog.cpp g++ -c -pipe -g -gdwarf-2 -arch i386 -Wall -W -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/local/Qt4.6/mkspecs/macx-g++ -I../TestMe -I/Library/Frameworks/QtCore.framework/Versions/4/Headers -I/usr/include/QtCore -I/Library/Frameworks/QtGui.framework/Versions/4/Headers -I/usr/include/QtGui -I/usr/include -I. -I../TestMe -I. -F/Library/Frameworks -o moc_finddialog.o moc_finddialog.cpp g++ -headerpad_max_install_names -arch i386 -o TestMe.app/Contents/MacOS/TestMe main.o finddialog.o moc_finddialog.o -F/Library/Frameworks -L/Library/Frameworks -framework QtGui -framework QtCore ld: duplicate symbol FindDialog::findNext(QString const&, Qt::CaseSensitivity) in moc_finddialog.o and finddialog.o collect2: ld returned 1 exit status make: *** [TestMe.app/Contents/MacOS/TestMe] Error 1 make: Leaving directory /Users/bruce/Projects/Qt Projects/TestMe-build-desktop'
The process "/usr/bin/make" exited with code %2.
Error while building project TestMe (target: Desktop)
When executing build step 'Make'

I have tried to figure this out, but don't seem to understand enough of what is going on with the moc process. If I comment out both the declaration and definition of the findNext() method, the compilation runs perfectly well. Can anybody help me with this? Seems like such a simple thing.

Thanks...

[edit: formatting fixed / Denis Kormalev]

[bmahf]

Oh, I didn't say that I'm on MacOS 10.6.4 running Qt 4.7 using QtCreator 2.0.0. I'm up to the latest on all three. Can't be my install, I'm assuming.

[Franzk]

In your header file, you have findNext() defined in the signals section. This means that MOC will generate a function findNext() as well, which causes the duplicate symbol. Move the findNext function to "(public|protected|private)(slots)?:"

The hint is given by: duplicate symbol FindDialog::findNext(QString const&, Qt::CaseSensitivity) in moc_finddialog.o and finddialog.o

So you would end up with for example:
@public slots:
void findNext(const QString &, Qt::CaseSensitivity); @

instead of

@signals:
void findNext(const QString &, Qt::CaseSensitivity); @

[bmahf]

Thank you very much. Such a simple thing. I knew it had to be a moc thing I wasn't understanding/remembering. Thanks a lot for helping. I'm on my way again. Whooppee!!! :)