Trivial QT app causes problem with -Werror

qtgui.cpp (text/x-c++src), 258 bytes, created by Stephen Lewis on 2022-09-19 23:00:22 UTC

#include <QApplication>
#include <QPushButton>

// g++ -fPIC $(pkg-config --cflags --libs Qt5Widgets) qtgui.cpp

int main(int argc, char **argv)
{
 QApplication app (argc, argv);

 QPushButton button ("Hello world !");
 button.show();

 return app.exec();
}