cLion + QT - Linker Error when using Q_OBJECT - c++

Question

I get a linker error if I put C_OBJECT into my header.
Currently I copy my QT dll library to my project, otherwise, I get exit code error as I don't know how to add QT library in cMake yet... Not sure if that is causing the error. Maybe I need to add Q_OBJECT in CMakeList.txt somehow?
Here is the sample code:
main.cpp
#include <iostream>
#include <QtWidgets/QApplication>
#include "testWidget.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
testWidget w;
w.show();
return a.exec();
}
testWidget.h
#ifndef QOBJECTCRASH_TESTWIDGET_H
#define QOBJECTCRASH_TESTWIDGET_H
#include <QtWidgets/QMainWindow>
class testWidget : public QMainWindow
{Q_OBJECT //this crashes the app. Remove it and all runs.
public:
testWidget(QWidget *parent = Q_NULLPTR);
};
#endif //QOBJECTCRASH_TESTWIDGET_H
testWidget.cpp
#include "testWidget.h"
testWidget::testWidget(QWidget *parent): QMainWindow(parent) {
setWindowTitle("Test Q_OBJECT");
setGeometry(500,500,500,500);
}
CMakeList.txt
cmake_minimum_required(VERSION 3.8)
project(QObjectCrash)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
set(CMAKE_CXX_STANDARD 14)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_PREFIX_PATH "C:\\Qt\\5.9\\mingw53_32")
set(SOURCE_FILES main.cpp testWidget.cpp testWidget.h)
add_executable(QObjectCrash ${SOURCE_FILES})
find_package(Qt5Core REQUIRED)
find_package(Qt5Widgets REQUIRED)
find_package(Qt5Gui REQUIRED)
qt5_use_modules(QObjectCrash Core Widgets Gui)
target_link_libraries(QObjectCrash Qt5::Widgets Qt5::Core Qt5::Gui)
Error print from cLion:
CMakeFiles\QObjectCrash.dir/objects.a(main.cpp.obj): In function `ZN10testWidgetD1Ev':
D:/QObjectCrash/testWidget.h:11: undefined reference to `vtable for testWidget'
D:/QObjectCrash/testWidget.h:11: undefined reference to `vtable for testWidget'
CMakeFiles\QObjectCrash.dir/objects.a(testWidget.cpp.obj): In function `ZN10testWidgetC2EP7QWidget':
D:/QObjectCrash/testWidget.cpp:7: undefined reference to `vtable for testWidget'
D:/QObjectCrash/testWidget.cpp:7: undefined reference to `vtable for testWidget'
collect2.exe: error: ld returned 1 exit status
CMakeFiles\QObjectCrash.dir\build.make:126: recipe for target 'QObjectCrash.exe' failed
mingw32-make.exe[3]: *** [QObjectCrash.exe] Error 1
CMakeFiles\Makefile2:66: recipe for target 'CMakeFiles/QObjectCrash.dir/all' failed
mingw32-make.exe[2]: *** [CMakeFiles/QObjectCrash.dir/all] Error 2
CMakeFiles\Makefile2:78: recipe for target 'CMakeFiles/QObjectCrash.dir/rule' failed
mingw32-make.exe[1]: *** [CMakeFiles/QObjectCrash.dir/rule] Error 2
mingw32-make.exe: *** [QObjectCrash] Error 2
Makefile:117: recipe for target 'QObjectCrash' failed
Thanks for help!