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I never use Valgrind before and today I tried to check memory leaks in simple Qt Widget application generated by Qt Creator. I created project by following steps:

1. I've got Qt Creator v4.8.1 based on Qt 5.12.0. In Qt Creator I chose following menu item: File -> New File or Project... -> Application -> Qt Widgets Application. Then I pressed Choose... -> Next -> ... -> Finish. Qt Creator generated following source code:

main.cpp:

#include "mainwindow.h"

#include <QApplication>



int main(int argc, char *argv)

{

    QApplication a(argc, argv);

    MainWindow w;

    w.show();



    return a.exec();

}

mainwindow.cpp:

#include "mainwindow.h"

#include "ui_mainwindow.h"



MainWindow::MainWindow(QWidget *parent) :

    QMainWindow(parent),

    ui(new Ui::MainWindow)

{

    ui->setupUi(this);

}



MainWindow::~MainWindow()

{

    delete ui;

}

mainwindow.h:

#ifndef MAINWINDOW_H

#define MAINWINDOW_H



#include <QMainWindow>



namespace Ui {

class MainWindow;

}



class MainWindow : public QMainWindow

{

    Q_OBJECT



public:

    explicit MainWindow(QWidget *parent = nullptr);

    ~MainWindow();



private:

    Ui::MainWindow *ui;

};



#endif // MAINWINDOW_H

mainwindow.ui

<ui version="4.0">

 <class>MainWindow</class>

 <widget class="QMainWindow" name="MainWindow" >

  <property name="geometry" >

   <rect>

    <x>0</x>

    <y>0</y>

    <width>400</width>

    <height>300</height>

   </rect>

  </property>

  <property name="windowTitle" >

   <string>MainWindow</string>

  </property>

  <widget class="QMenuBar" name="menuBar" />

  <widget class="QToolBar" name="mainToolBar" />

  <widget class="QWidget" name="centralWidget" />

  <widget class="QStatusBar" name="statusBar" />

 </widget>

 <layoutDefault spacing="6" margin="11" />

 <pixmapfunction></pixmapfunction>

 <resources/>

 <connections/>

</ui>

untitled.pro

#-------------------------------------------------

#

# Project created by QtCreator 2019-02-06T15:14:11

#

#-------------------------------------------------



QT       += core gui



greaterThan(QT_MAJOR_VERSION, 4): QT += widgets



TARGET = untitled

TEMPLATE = app



# The following define makes your compiler emit warnings if you use

# any feature of Qt which has been marked as deprecated (the exact warnings

# depend on your compiler). Please consult the documentation of the

# deprecated API in order to know how to port your code away from it.

DEFINES += QT_DEPRECATED_WARNINGS



# You can also make your code fail to compile if you use deprecated APIs.

# In order to do so, uncomment the following line.

# You can also select to disable deprecated APIs only up to a certain version of Qt.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0



CONFIG += c++11



SOURCES += 

        main.cpp 

        mainwindow.cpp



HEADERS += 

        mainwindow.h



FORMS += 

        mainwindow.ui



# Default rules for deployment.

qnx: target.path = /tmp/$${TARGET}/bin

else: unix:!android: target.path = /opt/$${TARGET}/bin

!isEmpty(target.path): INSTALLS += target

2. I compiled this project by GCC 8.2.0 toolchain in 'Debug mode' on Ubuntu 18.10.


3. 
   

   Then i tried to run compiled program by following command:

   
   
   

   $ valgrind ./untitled

   
   

Result of this operations on Ubuntu 18.10 is:

==12228== Memcheck, a memory error detector

==12228== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.

==12228== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info

==12228== Command: ./untitled

==12228== 

==12228== 

==12228== Process terminating with default action of signal 11 (SIGSEGV)

==12228==  General Protection Fault

==12228==    at 0x15C006A7: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x15C0DBC5: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x15C0DFEB: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x154B3172: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x159AF457: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x1587E5B1: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x1587984D: ??? (in /usr/lib/x86_64-linux-gnu/dri/vmwgfx_dri.so)

==12228==    by 0x14F8BD3D: ??? (in /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0.0.0)

==12228==    by 0x14F63C52: ??? (in /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0.0.0)

==12228==    by 0x14F5F323: ??? (in /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0.0.0)

==12228==    by 0x14F5FD3C: ??? (in /usr/lib/x86_64-linux-gnu/libGLX_mesa.so.0.0.0)

==12228==    by 0x14CFECF1: QXcbGlxWindow::createVisual() (in /opt/Software/Qt/5.12.0/gcc_64/plugins/xcbglintegrations/libqxcb-glx-integration.so)

==12228== 

==12228== HEAP SUMMARY:

==12228==     in use at exit: 3,561,397 bytes in 44,679 blocks

==12228==   total heap usage: 347,392 allocs, 302,713 frees, 29,095,722 bytes allocated

==12228== 

==12228== LEAK SUMMARY:

==12228==    definitely lost: 14,216 bytes in 80 blocks

==12228==    indirectly lost: 4,334 bytes in 203 blocks

==12228==      possibly lost: 28,587 bytes in 457 blocks

==12228==    still reachable: 3,448,988 bytes in 43,405 blocks

==12228==                       of which reachable via heuristic:

==12228==                         length64           : 3,376 bytes in 61 blocks

==12228==                         newarray           : 2,048 bytes in 48 blocks

==12228==         suppressed: 0 bytes in 0 blocks

==12228== Rerun with --leak-check=full to see details of leaked memory

==12228== 

==12228== For counts of detected and suppressed errors, rerun with: -v

==12228== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 4)

Segmentation fault (core dumped)

What am I doing wrong?