c++ - Must construct a QApplication before a QWidget & Invalid parameter passed to C runtime function

Question

I finished migrating an application from Qt4 to Qt5, it compiles and everything but it crashes at a certain point. I am debugging it and trying to find why but I have reached a dead end:

Here is the stack:

main.cpp line 373:

TouchSwibz w(NULL, NULL, renderMode ? renderMode : AppSettings::RASTERMODE);

When it reaches the breakpoint and I try to go further, it crashes with the usual

"This application has requested the Runtime to terminate it in an unusual way."

And the aplication output shows

QWidget: Must construct a QApplication before a QWidget
Invalid parameter passed to C runtime function.
Invalid parameter passed to C runtime function.

I have thought maybe its because the widget is being initialized when the main window is being created, but what can be done to solve this? What would be a good workaround? I dont even know if this is the real issue. I work under Windows 7 x64 using Qt 5.2.1 and compiling with mingw 4.8 32bit, the application is in 32bits also. Everything is compiled with the same kit. I dont know what other useful information I can provide. I tried stepping inside the QwtSlider constructor but I cant.

Answer 1

I managed to solve it by compiling all the libraries in debug mode, turns out having libraries in release mode while building your application in debug mode will make undefined behaviour happen.