The program crashes after using the plug-in！！！！

Hedge_tp

QT version: QT5.14.2
Environment: Windows10
Compiler: MSVC2017_64

Problem description: The program has two interfaces. Interface A is MainWindow, inherited from QMainWindow, interface B is Form, inherited from QWidget, and both interfaces have QLineEdit. When using a plug-in (optional plug-in), there is no problem when entering QLineEdit on interface A. When interface B pops up from interface A, when entering QLineEdit on interface B (input by keyboard), the program will crash.

Source code:
main.cpp:

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
//    // The self-defined soft keyboard will crash when typing in interface B
//    qputenv("QT_IM_MODULE", QByteArray("tgtsml"));
//    // The system soft keyboard will also crash
//    qputenv("QT_IM_MODULE", QByteArray("qtvirtualkeyboard"));

    qputenv("QT_IM_MODULE", QByteArray("111"));

    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

mainwindow.h：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "form.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private slots:
    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
    Form *form;

};
#endif // MAINWINDOW_H

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;
}

void MainWindow::on_pushButton_clicked()
{
    form = new Form();
    form->show();
}

form.h:

#ifndef FORM_H
#define FORM_H

#include <QWidget>

namespace Ui {
class Form;
}

class Form : public QWidget
{
    Q_OBJECT

public:
    explicit Form(QWidget *parent = nullptr);
    ~Form();

private:
    Ui::Form *ui;
};

#endif // FORM_H

form.cpp:

#include "form.h"
#include "ui_form.h"

Form::Form(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Form)
{
    ui->setupUi(this);
}

Form::~Form()
{
    delete ui;
}

Because I caused a crash when I used the soft keyboard, I finally found the above problem

mrdebug

try form = new Form(this);
Try to run the program in debug mode

Hedge_tp

Hello, thank you for your reply. I tried, but the result is still the same

Christian Ehrlicher

@Hedge_tp Please use a debugger and see where exactly it crashes as @mrdebug already told you.