Declaring variables in header file of QT causes program to unexpectedly finish

Question

I have a project "Cybaware_ver1" on QtCreator based on QWidget and everything was working fine. I have a header file with a class containing public and private variables and functions. However, since one day whenever I try to declare a new variable in the header file, even an "int" variable, and run the project, I get

The program has unexpectedly finished.
/home/devdeep/Cybaware_ver1-build-Desktop_Qt_5_0_0_GCC_64bit_SDK-Debug/Cybaware_ver1       exited with code 0

Previously I could add variables in the header file without any problem. Currently, I am able to add new functions, modify UI etc. Just I am unable to add variables to the header file. I have found a temporary solution of declaring these variables as static in the cpp file. However, I would like to find a solution to this. I have tried re-installing Qt but the problem still persists. I am running it on Ubuntu Linux. Please let me know if there is a way to fix this. Also, I am not sure what other information I can provide. So please let me know about that.

UPDATE: OK. I used the debugger at it says that the error is a segmentation fault. It points to the following section of qdebug.h and to the line marked by qt_message_output.

public:
inline QDebug(QIODevice *device) : stream(new Stream(device)) {}
inline QDebug(QString *string) : stream(new Stream(string)) {}
inline QDebug(QtMsgType t) : stream(new Stream(t)) {}
inline QDebug(const QDebug &o):stream(o.stream) { ++stream->ref; }
inline QDebug &operator=(const QDebug &other);
inline ~QDebug() {
    if (!--stream->ref) {
        if(stream->message_output) {
            QT_TRY {
                qt_message_output(stream->type,
                                  stream->context,
                                  stream->buffer);
            } QT_CATCH(std::bad_alloc&) { /* We're out of memory - give up. */ }
        }
        delete stream;
    }
}

I guess it is a out of memory error. Possible, closing other programs might help?

UPDATE2: Calling "run qmake" did not help. Here is my header file:

#ifndef MAINVIEW_H
#define MAINVIEW_H

#include <QWidget>
#include <QGraphicsScene>
#include <QGraphicsRectItem>
#include <QGraphicsLineItem>
#include <QGraphicsEllipseItem>
#include <QGraphicsSimpleTextItem>
#include <list>
#include <QMouseEvent>
#include <QEvent>
#include <QString>
#include <boost/thread.hpp>
#include <qcustomplot.h>
#include <QTimer>
namespace Ui {
class MainView; 
}

class MainView : public QWidget
{
Q_OBJECT

public:
int num_missions;
int num_services;
int timer;


int* num_servpermission;
int missionstartx;
//boost::thread pt;
QGraphicsScene mynewscene;
QGraphicsRectItem* myrect;
QGraphicsRectItem** missionline;
QGraphicsLineItem** missionplayline;
QGraphicsRectItem** playrect;
std::list<QGraphicsLineItem**> missionticks;
std::list<QGraphicsEllipseItem**> missionservices;
std::list<QGraphicsSimpleTextItem**> missionservicesno;
std::list<QGraphicsLineItem**>::iterator ti;
std::list<QGraphicsSimpleTextItem**>::iterator ssi;
//std::list<QGraphicsEllipseItem**>::iterator si;

int* missionlength;
int** missionplayxy;
int* missiontickscount;
int* missioniteration;
int missionselected;
int missiontickselected;
int missiontickoffset;
bool isrepeated;

int temp;


QCustomPlot** customPlot;
QTimer dataTimer;

explicit MainView(QWidget *parent = 0);
void playthread();

bool eventFilter(QObject*, QEvent*);
void testfunc();
void clearview();
void test1();

~MainView();

private slots:
void on_startButton_clicked();
void realtimeDataPlot();

void on_pushButton_clicked();

private:
Ui::MainView *ui;



};


#endif // MAINVIEW_H

The program crashes on adding any variable. For example, I added the variable int temp just now and it would crash. Adding anything new makes it crash such as uncommenting the declaration std::list::iterator si;. I take it out and everything works fine.

UPDATE3: My external header file qcustomplot.h is located in the same directory. I am also using boost but that I set up using apt-get. Here is the stack trace:

0 MainView::playthread mainview.cpp 530 0x418fa1
1 boost::_mfi::mf0::operator() mem_fn_template.hpp 49 0x424690
2 boost::_bi::list1 >::operator(), boost::_bi::list0> bind.hpp 253 0x424600
3 boost::_bi::bind_t, boost::_bi::list1 > >::operator() bind_template.hpp 20 0x4245af
4 boost::detail::thread_data, boost::_bi::list1 > > >::run thread.hpp 61 0x42431c
5 thread_proxy /usr/lib/libboost_thread.so.1.46.1 0x7ffff7bcfba9
6 start_thread /lib/x86_64-linux-gnu/libpthread.so.0 0x7ffff6557efc
7 clone /lib/x86_64-linux-gnu/libc.so.6 0x7ffff5af159d
8 ??

The 0th pt in the above trace points to ui->missionview->invalidateScene() Here the graphics view gets updated from a function playthread binded to a boost thread. But I am not sure why this would be a problem on adding a variable in the header file as I am not using the variable anywhere in the cpp file.

What does the debugger say? Do you do a rebuild after adding the variable to the header? — cmannett85, Feb 02 '13 at 16:41
Is the header in another directory? Then you might run into this: http://stackoverflow.com/questions/5470438/why-are-changes-in-source-not-always-reflected-in-machine-code-after-build-while — Frank Osterfeld, Feb 02 '13 at 18:45

score 1 · Answer 1 · answered Mar 18 '21 at 20:48

Go into the project folder and delete the *.pro.user file. Next time you open the project you'll just need to reconfigure it (i.e. choose the appropriate build kit).

I know this is an old thread, but I ran into the same problem myself. Every time I tried to add a variable to my header file it was causing a heap corruption error. I wasn't allocating memory on the heap, or even declaring pointer variables for that matter. It was very frustrating because I didn't know what it was at first. I finally narrowed it down to adding variables to my header file causing the crash. Based on doomguy's experience I knew that it was something persistent in the build folder because he said reinstalling Qt didn't work. I'm glad I read that because I would have been pissed if I reinstalled this behemoth and it still didn't work. Based on prior experience corruption in the .user file can cause issues, and deleting it kinda gives you a clean slate. Moral of the story: If you're getting unusual behavior that seems to point to a problem in the IDE try deleting the .user file before trying more extreme measures.

Zlatomir · Answer 2 · 2013-02-02T22:01:06.790

0

Not sure if the problem is cause by this, but if the header contains a QObject derived class you should run qmake and after that build your application.

LE: also if this isn't the case, i suggest that you show us a little more code (your code, not Qt code)

edited Feb 02 '13 at 22:01

answered Feb 02 '13 at 17:18

Zlatomir

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Declaring variables in header file of QT causes program to unexpectedly finish

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