Use of QFileDialog::DontUseNativeDialog crashes on some system and not using flag crashes on others

#include <QtCore\qfile.h>
#include <QtWidgets\qfiledialog.h>
#include <QtWidgets\qapplication.h>
#include <iostream>

int main(int argc, char* argv[])
{
    const char* Title = "Open";
    const char* Dir = "D:\\test";
    const char* Filter = "*.cpp";

    QApplication* QApp = new QApplication(argc, argv);

    QWidget window;
    window.setFixedSize(500, 500);

    //QString f = QFileDialog::getSaveFileName(0, Title, 0, Filter, 0);

    QString f = QFileDialog::getSaveFileName(0, Title, Dir, Filter, 0, QFileDialog::Option::DontUseNativeDialog);

    if (f.isEmpty() == true)
    {
        std::cout << "No Flag, butEmpty file name\n";
    }
    else
    {
        char FileName[100];
        strcpy(FileName, f.toLatin1().data());

        std::cout << "No flag Filename: " << FileName << "\n";
    }

    return 0;
}