qt undefined reference to `vtable for subClass'

1. 建立一个console工程

QT -= gui

CONFIG += c++11 console
CONFIG -= app_bundle

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += 
        main.cpp 
    baseclass.cpp 
    subclass.cpp

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

HEADERS += 
    baseclass.h 
    subclass.h

2. 添加baseClass

baseclass.h

#ifndef BASECLASS_H
#define BASECLASS_H

#include "QObject"

class baseClass: public QObject
{
    Q_OBJECT

public:
    baseClass(QObject * p = 0);
    virtual ~baseClass() {}

signals:
    void signal1();


};

#endif // BASECLASS_H

baseClass.cpp

#include "baseclass.h"

baseClass::baseClass(QObject * p) : QObject(p)
{

}

subclass.h

#ifndef SUBCLASS_H
#define SUBCLASS_H

#include "baseclass.h"

class subClass: public baseClass
{
    Q_OBJECT

public:
    subClass(QObject * p = 0);
    virtual ~subClass() {};

//signals:
    void signal2();

};

#endif // SUBCLASS_H

subclass.cpp

#include "subclass.h"

subClass::subClass(QObject * p) : baseClass (p)
{

}

main.cpp

#include <QCoreApplication>
#include "subclass.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);


    subClass * sub = new subClass();

    return a.exec();
}

编译报错：

testQtSignalBug/subclass.cpp:14: error: undefined reference to `vtable for subClass'

collect2: error: ld returned 1 exit status

解决办法：注释掉subclass.h里的Q_OBJECT 宏

原因：未知