Qt 4.7.4 Qt 5.8 QFileInfo does not work

Question

I have a problem migrating my code from Qt 4.7.4 to Qt 5.8:

In my old code I use

void GuiUtil::setLastPath(QString path)
{
    QFileInfo finfo(path);
    if (finfo.isDir())
        GuiUtil::get()->lastPath = finfo.absoluteFilePath();
    else
        GuiUtil::get()->lastPath = finfo.absolutePath();
}

When I migrate this to Qt 5.8 my code compiles but finfo is not accessible.

Does anybody know why?

The problem is in the first line

QFileInfo finfo(path);

where from the beginning path is my directory path = "C:/Users/s" type QString

After completing this line fifo is set to

fifo  = "C:/Users/s"  type QFileInfo  ( in Qt 4.7.4)

fifo  = ""            type QFileInfo  ( in Qt 5.8)