QFileDialog of qt5 displays only directories when I use QFileDialog::Directory.

http://doc.qt.io/qt-5/qfiledialog.html#FileMode-enum
This document describes that "QFileDialog::Directory" displays both files and directories.
But I wrote a simple program like I attatched, it displays only directory if I use qt5( g++ test.cpp $(pkg-config --libs --cflags Qt5Widgets) -std=c++11 -fPIC ).
And if I use qt4( g++ test.cpp $(pkg-config --libs --cflags QtGui) -std=c++11 -fPIC ), it displays both files and directories as the document described(and as I expected).

Steps to reproduce

1. just compile test.cpp with qt5 and execute it.

Expected result

It displays both files and directories.

Actual result

It displays only directories.