Can't build Qt-Widgets Application using CMake

I am trying to setup a CMake Project building a Qt-Widgets application but can't compile it properly. My project structure is as follows:

• include/
  • mainwindow.hpp
• resources/
  • mainwindow.ui
• src/
  • main.cpp
  • mainwindow.cpp
• CMakeLists.txt

CMakeLists.txt

cmake_minimum_required(VERSION 3.10)find_package(Qt5 COMPONENTS Widgets REQUIRED)project(Test VERSION 0.1 LANGUAGES CXX)set(CMAKE_CXX_STANDARD 11)set(CMAKE_CXX_STANDARD_REQUIRED ON)set(CMAKE_EXPORT_COMPILE_COMMANDS ON)set(CMAKE_AUTOUIC ON)set(CMAKE_AUTOMOC ON)set(CMAKE_AUTOUIC_SEARCH_PATHS resources)add_executable(App src/mainwindow.cpp src/main.cpp resources/mainwindow.ui)target_include_directories(App PRIVATE include)target_link_libraries(App PRIVATE Qt5::Widgets)

mainwindow.hpp

#ifndef MAINWINDOW_HPP_#define MAINWINDOW_HPP_#include <QMainWindow>QT_BEGIN_NAMESPACEnamespace Ui { class MainWindow; }QT_END_NAMESPACEclass Test : public QMainWindow {    Q_OBJECTpublic:    Test(QWidget *parent = nullptr);    ~Test();private:    Ui::MainWindow *ui;};#endif // MAINWINDOW_HPP_

mainwindow.cpp

#include "mainwindow.hpp"#include "ui_mainwindow.h"Test::Test(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow){    ui->setupUi(this);}Test::~Test(){    delete ui;}

main.cpp

#include "mainwindow.hpp"#include <QApplication>int main(int argc, char *argv[]){    QApplication a(argc, argv);    Test w;    w.show();    return a.exec();}

When I'm trying to build the project:

cmake -Bbuild -DCMAKE_BUILD_TYPE=Debugcmake --build build --target all

I get the following linker error:

[ 20%] Automatic MOC and UIC for target App[ 20%] Built target App_autogen[ 40%] Building CXX object CMakeFiles/App.dir/App_autogen/mocs_compilation.cpp.o[ 60%] Building CXX object CMakeFiles/App.dir/src/mainwindow.cpp.o[ 80%] Building CXX object CMakeFiles/App.dir/src/main.cpp.o[100%] Linking CXX executable App/usr/bin/ld: CMakeFiles/App.dir/src/mainwindow.cpp.o: in function `Test::Test(QWidget*)': .../src/mainwindow.cpp:4: undefined reference to `vtable for Test'/usr/bin/ld: .../src/mainwindow.cpp:4: undefined reference to `vtable for Test'/usr/bin/ld: CMakeFiles/App.dir/src/mainwindow.cpp.o: in function `Test::~Test()': .../src/mainwindow.cpp:8: undefined reference to `vtable for Test'/usr/bin/ld: .../src/mainwindow.cpp:8: undefined reference to `vtable for Test'collect2: error: ld returned 1 exit statusmake[2]: *** [CMakeFiles/App.dir/build.make:132: App] Error 1make[1]: *** [CMakeFiles/Makefile2:84: CMakeFiles/App.dir/all] Error 2make: *** [Makefile:91: all] Error 2

Looking at cmakes generated link.txt, it seems that the required object files are linked properly

/usr/bin/c++ \    -g CMakeFiles/App.dir/App_autogen/mocs_compilation.cpp.o \       CMakeFiles/App.dir/src/mainwindow.cpp.o \       CMakeFiles/App.dir/src/main.cpp.o \    -o App \       /usr/lib/libQt5Widgets.so.5.15.4 \       /usr/lib/libQt5Gui.so.5.15.4 \       /usr/lib/libQt5Core.so.5.15.4 

Im not really sure, why the vtable references are undefined. What am I doing wrong here?