@Pl45m4 Yes im using a plain windows 10 system. And yes the linked bug is with MSys2 as i searched for a similar problem and this was the only thing related i could find.
Found it odd myself that i worked inside qt creator but crashed outside (as said i tried windeploy and run dependency walker but haven't found a problem there)

As said using llvm solves it for me but still wanted to point it out for others may experiencing something simlar.

@Christian-Ehrlicher i posted all code above simply create a new project and add in my code for maindwindow.h and .cpp. There is nothing else in my project.