Can't find the invalid pointer

Gallo Magico

I'm working with qt5.15 in qtCreator in ubuntu 20.04 and g++. My program compiles and works fine until I close the main window becuase I get the error in the title of the question. I read that this error occurs when there is a invalid pointer, I tried to find it in my program but I couldnt.

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.h

#pragma once

#include "Facelet.h"
#include "Face.h"

#include <QMainWindow>
#include <QWidget>
#include <QSpacerItem>

class MainWindow : public QMainWindow
{
    Q_OBJECT

    using type = Face;

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

protected:

    virtual void resizeEvent(QResizeEvent*) override;

private:

    void __init_spacers();

    QWidget* wid;
    type* object;
    QGridLayout* layout;
    QSpacerItem* spacer;

};

MainWindow.cpp

#include "MainWindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    object = new type();
    layout = new QGridLayout();
    wid = new QWidget();
    __init_spacers();
    layout->setContentsMargins(0,0,0,0);
    layout->addWidget(object, 1, 1);
    wid->setLayout(layout);
    setCentralWidget(wid);
}

MainWindow::~MainWindow()
{
    delete spacer;
    delete object;
    delete layout;
    delete wid;
}

//protected

void MainWindow::resizeEvent(QResizeEvent*) {
    int side = (size().width() < size().height()) ? size().width() : size().height();
    object->resize(side, side);
}

//private

void MainWindow::__init_spacers() {
    spacer = new QSpacerItem(0,0, QSizePolicy::Expanding, QSizePolicy::Expanding);
    layout->addItem(spacer, 0, 1);//top
    layout->addItem(spacer, 1, 0);//left
    layout->addItem(spacer, 2, 1);//bootom
    layout->addItem(spacer, 1, 2);//right
}

Face.h

#pragma once

#include "Facelet.h"
#include <QGridLayout>

class Face : public QWidget {

    Q_OBJECT

public:

    explicit Face(QWidget* parent = nullptr);
    ~Face();

    std::string get_pattern();

protected:

    virtual void resizeEvent(QResizeEvent *event = nullptr) override;

private:

    void __init_widget();
    void __init_layout();
    void __init_facelets();
    void __update_facelets(int side);
    void __delete_facelets();

    Facelet** facelets;
    QGridLayout* layout;

    constexpr static unsigned int SIDE = 248;
    constexpr static unsigned int SPACE = 10;

};

Face.cpp

#include "Face.h"

Face::Face(QWidget* parent) : QWidget(parent) {
    __init_facelets();
    __update_facelets(75);
    __init_layout();
    __init_widget();
}

Face::~Face() {
    __delete_facelets();
    delete layout;
}

std::string Face::get_pattern() {
    std::string result;
    for(int i = 0; i < 3; ++i) {
        for(int j = 0; j < 3; ++j) {
            result.push_back( char(Colors::list[facelets[i][j].id()].second) );
        }
    }
    return result;
}

//protected

void Face::resizeEvent(QResizeEvent *event) {
    int side = (size().width() > size().height()) ? size().width() : size().height();
    int facelet_side = (side-8)/3;
    __update_facelets(facelet_side);
}

//private

void Face::__init_widget() {
    this->resize(SIDE, SIDE);
    this->setMinimumSize(SIDE, SIDE);
    this->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
    this->setAttribute(Qt::WA_StyledBackground);
    this->setStyleSheet("background-color: black;");
    this->setLayout(layout);
}

void Face::__init_layout() {
    layout = new QGridLayout();
    layout->setSpacing(2);
    layout->setContentsMargins(2, 2, 2, 2);
    for(int i = 0; i < 3; ++i) {
        for(int j = 0; j < 3; ++j) {
            layout->addWidget(&facelets[i][j], i, j);
        }
    }
}

void Face::__init_facelets() {
    facelets = new Facelet*[3];
    for(int i = 0; i < 3; ++i) {
        facelets[i] = new Facelet[3];
    }
}

void Face::__update_facelets(int side) {
    for(int i = 0; i < 3;++ i) {
        for(int j = 0; j < 3; ++j) {
            facelets[i][j].setFixedSize(side, side);
        }
    }
}

void Face::__delete_facelets() {
    for(int i = 0; i < 3; ++i) {
        delete[] facelets[i];
    }
    delete[] facelets;
}

Facelette.h

#pragma once

#include "Colors.h"

#include <QPushButton>
#include <QPainter>

class Facelet : public QPushButton {

    Q_OBJECT

public:

    using id_type = Colors::Id;

    explicit Facelet(QWidget* parent = nullptr);
    explicit Facelet(Colors::Id color, QWidget* parent = nullptr);
    virtual ~Facelet();

    void reset();
    void set_color(Colors::Id);
    id_type id();

protected:
    virtual void paintEvent(QPaintEvent *e = nullptr) override;

public slots:

    void __change_color();

private:
    
    int _Id;

};

Facelet.cpp

#include "Facelet.h"
#include <QStyleOption>

Facelet::Facelet(QWidget* parent) : QPushButton(parent) {
    reset();
    connect(this, SIGNAL(clicked()), SLOT(__change_color()));
}

Facelet::Facelet(Colors::Id id_, QWidget* parent) : QPushButton(parent) {
    set_color(id_);
    connect(this, SIGNAL(clicked()), SLOT(__change_color()));
}

Facelet::~Facelet() {}

void Facelet::reset() {
    _Id = -1;
    this->setStyleSheet("background-color:lightGray;");
}

void Facelet::set_color(Colors::Id _id) {
    _Id = _id;
    setStyleSheet(QString("background-color:")+Colors::list[_Id].first+";");
}

Facelet::id_type Facelet::id() {
    return Facelet::id_type(_Id);
}

//protected

void Facelet::paintEvent(QPaintEvent *) {
    QStyleOption opt;
    opt.init(this);
    QPainter p(this);
    style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
}

//private slots

void Facelet::__change_color() {
    _Id = (_Id >= 5) ? 0 : (_Id+1);
    set_color(Colors::Id(_Id));
}

Colors.h

#pragma once

#include "Rubix/Rubix.h"

#include <array>
#include <utility>
#include <QColor>


struct Colors {

    using value_type = typename std::pair<QString, rbx::RColor>;
    using array_type = typename std::array<value_type, 6>;
    enum Id { Yellow, Red, Green, Orange, Blue, White };
    static array_type list;

};

Colors.cpp

#include "Colors.h"

Colors::array_type Colors::list = {
    Colors::value_type("yellow", rbx::YELLOW),
    Colors::value_type("rgb(255, 20, 20)", rbx::RED),
    Colors::value_type("rgb(35, 255, 35)", rbx::GREEN),
    Colors::value_type("rgb(255, 130, 20)", rbx::ORANGE),
    Colors::value_type("blue", rbx::BLUE),
    Colors::value_type("white", rbx::WHITE),
};

when I close the window I get the following error

21:07:22: Starting /home/kubuntu/Desktop/projects/x64/RubbixSolver/Debug/GUI/build-GUI-Desktop_Qt_5_15_2_GCC_64bit-Profile/GUI ...
21:07:46: The program has unexpectedly finished.
21:07:46: The process was ended forcefully.
21:07:46: /home/kubuntu/Desktop/projects/x64/RubbixSolver/Debug/GUI/build-GUI-Desktop_Qt_5_15_2_GCC_64bit-Profile/GUI crashed.

If I start the debug when I close the main window it says there is a problem in Face::~Face(), a small message-window pops up with the following message'The inferior stopped because it received a signal from the operating system. Signal name : SIGSEGV Signal meaning : Segmentation fault, the conosle debug displays a bounch of ```
RTTI symbol not found for class 'QObject'

nagesh

@Gallo-Magico said in Can't find the invalid pointer:

void Face::__delete_facelets() {
for(int i = 0; i < 3; ++i) {
delete[] facelets[i];
}
delete[] facelets;
}

@Gallo-Magico I feel in destructor you are doing double deletion.
deleting the memory which was already deleted.

delete[] facelets; //comment it out

Gallo Magico

@nagesh getting the same error in the same destructor, I also tried to uncomment delete layout but I always get the same error

nagesh

void Face::__init_layout() {
....
layout->addWidget(&facelets[i][j], i, j);
}

You have added the facelets objects to the layout.
The ownership of item is transferred to the layout, and it's the layout's responsibility to delete it.
I feel no need to free the memory in the destructor for the facelets and as well as layout.

Refer object tree & ownership details
https://doc.qt.io/qt-5/objecttrees.html

Gallo Magico

@nagesh I still get error but is a different message

The inferior stopped because it received a signal from the operating system.

Signal name : 
SIGABRT
Signal meaning : 
Aborted

I get this error in Facelet::~Facelet() and the console application displays munmap_chunk(): invalid pointer.
I also tried to turn facelets into a Facelet*** and treat Facelet[i][j] as a pointer instead as an object, but I get the same error I got at the begin

nagesh

@Gallo-Magico do you still get these errors when you are not deleting/freeing?

//__delete_facelets();
    //delete layout;

Gallo Magico

@nagesh yes

VRonin

@Gallo-Magico said in Can't find the invalid pointer:

MainWindow::~MainWindow()
{
delete spacer;
delete object;
delete layout;
delete wid;
}

Same problem here. If QObjects have a parent they get deleted when the parent gets deleted automatically, if you do it manually it's a double deletion.
If debugging is becoming a mess change the type of your QObjects pointer to QPointer so the pointers will be set to null automatically on deletion and you won't be able to double-delete them

kshegunov

@VRonin said in Can't find the invalid pointer:

Same problem here. If QObjects have a parent they get deleted when the parent gets deleted automatically, if you do it manually it's a double deletion.

No it is not. The child notifies the parent when it goes away, so the parent detaches it from the list.

Christian Ehrlicher

@kshegunov said in Can't find the invalid pointer:

No it is not. The child notifies the parent when it goes away, so the parent detaches it from the list.

@VRonin forgot a sentence in if you do it manually it's a double deletion. - if you do it manually after the parent deleted it's children it's a double deletion :)

Gallo Magico

@VRonin I already deleted those too, but now I'm getting an error in Facelet::~Facelet(), the error is

The inferior stopped because it received a signal from the operating system.

Signal name : 
SIGABRT
Signal meaning : 
Aborted

Gallo Magico

I figured out,there were a bounch of problem, first of all I used to double delete child widgets, like the layout(child of the main widget) and the other widget into the layout(child of the layout), then I got all my destructors empty but I got an error caused by deleting a location memory not allocated with new. In my case the dynamic matrix of facelet don't allocate the memory for each Facelet, then I turned facelets from Facelet** facelets into a Facelet*** facelets and changed init_facelets() to

void Face::init_facelets() {
    facelets = new Facelet**[3];
    for(int i = 0; i < 3; ++i) {
        facelets[i] = new Facelet*[3];
        for(int j = 0; j < 3; ++j) {
            facelets[i][j] = new Facelet();
        }
    }
}

When the program ends, Face::~Face() frees all the location corresponding to facelets[i][j], then I had to free the rest of the matrix, so now Face::~Face() looks like

Face::~Face() {
    for(int i = 0; i < 3; ++i) {
        delete[] facelets[i];
    }
    delete[] facelets;
}

Now it works with no problem or any issue

VRonin

@Gallo-Magico said in Can't find the invalid pointer:

layout->addWidget(&facelets[i][j]

This sets Face as parent of facelets[i][j] so same error as before you are double deleting a QObject as the parent already deleted it

No it is not. The child notifies the parent when it goes away, so the parent detaches it from the list.

Good observation, I didn't explain myself well there.

P.S.
from https://en.cppreference.com/w/cpp/keyword

identifiers with a double underscore anywhere are reserved

identifiers that begin with an underscore followed by an uppercase letter are reserved

You should rename your methods/members

Gallo Magico

@VRonin I know about the methods that begin with __, I already changed