VirtualKeyboard, Program crash when input out of range char to a QLineEdit with validator

[Anima]

I write a minimul example here:
main.cpp

#include "QtGuiApplication1.h"
#include <QtWidgets/QApplication>

int main(int argc, char *argv[])
{
    qputenv("QT_IM_MODULE", "qtvirtualkeyboard");
    QApplication a(argc, argv);
    QtGuiApplication1 w;
    w.show();
    return a.exec();
}

QtGuiApplication1.h

#pragma once

#include <QtWidgets/QMainWindow>
#include <QPushButton>

class QtGuiApplication1 : public QMainWindow
{
    Q_OBJECT

public:
    QtGuiApplication1(QWidget *parent = Q_NULLPTR);

public slots:
    void onBtnClicked();

private:
    QPushButton*    m_pBtn;
};

QtGuiApplication1.cpp

#include "QtGuiApplication1.h"

#include "MyDialog.h"

QtGuiApplication1::QtGuiApplication1(QWidget *parent)
    : QMainWindow(parent)
{
    m_pBtn = new QPushButton("Click Me");
    setCentralWidget(m_pBtn);

    connect(m_pBtn, SIGNAL(clicked()), this, SLOT(onBtnClicked()));
}

void QtGuiApplication1::onBtnClicked()
{
    MyDialog dlg;
    dlg.exec();
}

MyDialog.h

#pragma once

#include <QDialog>
#include <QLineEdit>

class MyDialog : public QDialog
{
public:
    MyDialog();
    ~MyDialog();

private:
    QLineEdit*  m_pEdit;
};

MyDialog.cpp

#include "MyDialog.h"

#include <QRegExpValidator>

MyDialog::MyDialog()
{
    m_pEdit = new QLineEdit(this);
    m_pEdit->setValidator(new QRegExpValidator(QRegExp(u8"^([0-9]|[1-9][0-9]{1,2})")));
}

MyDialog::~MyDialog()
{
}

When I input "a" from real keyboard, the program crashes.

[SGaist]

Hi and welcome to devnet,

Can you show the stack trace of your crash ?
Do you have the same issue if you use a QRegularExpressionValidator ?

[Anima]

@SGaist said in VirtualKeyboard, Program crash when input out of range char to a QLineEdit with validator:

QRegularExpressionValidator

Thanks, SGaist.
And Yes. I tryed QRegularExpressionValidator and QIntValidator, still got the same result:

    m_pEdit->setValidator(new QRegularExpressionValidator(QRegularExpression(u8"^([0-9]|[1-9][0-9]{1,2})")));
//  m_pEdit->setValidator(new QIntValidator(0, 100));

And I noticed that, if I directly put the QLineEdit on MainWindow other than MyDialog, everything is OK.

[Anima]

The stack trace.

[Anima]

@SGaist
Do you have any suggestion? Thank you.

[SGaist]

What if you use the following:

MyDialog::MyDialog(QWidget *parent):
    QDialog(parent)
{
     m_pEdit = new QLineEdit(this);
     m_pEdit->setValidator(new QRegularExpressionValidator(QRegExp(u8"^([0-9]|[1-9][0-9]{1,2})")));
}
 
MyDialog::~MyDialog()
{
}

?

[zhangqinagqiag]

This problem also exists in 5.15.2，As long as it is a pop-up window and uses both virtual keyboard and physical keyboard, it will crash

[SGaist]

Which compiler are you using ?

[Anima]

@SGaist
Thanks.
The issue still exists after set the parent of MyDialog.
The compiler I'm using is Microsoft Visual C++ compiler 14.0.
I also tried MinGW 8.1.0 on Windows 10, got the same issue.

But on Ubuntu 18.04, the same program, built by Qt5.12.10 and g++, works fine. I think it may be a platfrom specific bug.

[SGaist]

Might be indeed.

One last test, what happens if you use open in place of exec ?

[Anima]

@SGaist
I modified the program as below, and still got the same result. Program crashed after I tapped illegal keys with physical keyboard.

void QtGuiApplication1::onBtnClicked()
{
    MyDialog* dlg = new MyDialog(this);
    dlg->open();
}

[SGaist]

Then I would say a bug report is the next step.

[Anima]

The issue is a known bug QTBUG-9304.
Unfortunately, it will not be fixed for Qt5.12.

[SGaist]

From the looks of the patch, you should be able to port it to 5.12 and build the module yourself with it.