c++ Qt inheriting from QWidget gives linking error re missing vtable

Question

I am on MacOS and I want to inherit QWidget for a class with QObject:: connect but i have a error:

Undefined symbols for architecture x86_64: "vtable for Core", referenced from: Core::Core(QWidget*) in Core.cpp.o NOTE: a missing vtable usually means the first non-inline virtual member function has no definition. ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation) make[2]: *** [bin/babel] Error 1 make[1]: *** [CMakeFiles/babel.dir/all] Error 2

Core.cpp

** EPITECH PROJECT, 2020
** Babel
** File description:
** Core
*/

#include "../include/Core.hpp"

Core::Core(QWidget *parent) : QWidget(parent)
{
    this->text = new QLabel("Pseudo", this);
    this->textArea = new QTextEdit(this);
    this->button = new QPushButton("Connexion", this);

    QObject::connect(this->button, SIGNAL(clicked()), this, SLOT(this->buttonPushed()));
    this->button->setGeometry(300, 250, 160, 30);
    this->textArea->setGeometry(300, 200, 160, 30);
    this->text->setGeometry(335, 175, 160, 30);
}

Core::~Core()
{
    
}

void Core::buttonPushed()
{
    printf("EKIP EKIP EKIP\n");
}

Core.hpp:

/*
** EPITECH PROJECT, 2020
** Babel
** File description:
** Core
*/

#ifndef CORE_HPP_
#define CORE_HPP_

#include <stdio.h>
#include <stdlib.h>
#include <opus/opus.h>
#include <portaudio.h>
#include <QtWidgets>

class Core : public QWidget {
    Q_OBJECT
    public:
        explicit Core(QWidget *parent = nullptr);
        ~Core();
    protected:
    private slots:
        void buttonPushed();
    private:
        // QApplication *app;
        QPushButton *button;
        QLabel *text;
        QTextEdit *textArea;
};

#endif /* !CORE_HPP_ */

and Main.cpp

/*
** EPITECH PROJECT, 2020
** Babel
** File description:
** main
*/

#include "../include/Core.hpp"

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    Core *core = new Core();
    core->setGeometry(10, 10, 720, 480);
    core->setWindowTitle("Babel");
    core->show();
    return app.exec();
}

Cmake file:

project(Babel)
cmake_minimum_required(VERSION 2.8.12)
add_definitions("-fPIC")

SET(CMAKE_AUTOMOC ON)
SET(CMAKE_AUTOUIC ON)

include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
conan_basic_setup()

find_package(Qt5Widgets REQUIRED)

find_package(Qt5Core)
find_package(Qt5Network)

file(GLOB_RECURSE BABEL_SRC PATH ./sources/*.cpp)

include_directories(${CMAKE_INCLUDE_PATH})
add_executable(babel ${BABEL_SRC})
target_link_libraries(babel ${CONAN_LIBS} Qt5::Widgets Qt5::Core Qt5::Network)

Answer 1

add the files with Q_OBJECT in the cmake like this for example:

set(SOURCES core.cpp )
qt5_wrap_cpp(SOURCES core.hpp)


add_executable(babel ${SOURCES} ${BABEL_SRC})