Can't get enumeration on library (undefined reference staticMetaObject) - c++

Question

I have an application which uses a Qt library (shared library). On my library, I have a class with several enumerations which I want use on main application.
I build my library project without problem but I when I build main application project, I have the error :
moc_myapp.cpp:-1: erreur : undefined reference to `MyClass::staticMetaObject'
I didn't find information about this error.
This is my Biblio .pro
QT -= gui
QT += quick multimedia network
TARGET = MyBiblio
TEMPLATE = lib
DEFINES += MYBIBLIO_LIBRARY
SOURCES += myBiblio.cpp
HEADERS += myBiblio.h\
myBiblio_global.h \
myClass.h
This myClass.h :
#ifndef MYCLASS_H
#define MYCLASS_H
#include <QObject>
class MyClass : public QObject
{
Q_OBJECT
public:
enum MyEnumeration {Enum1, Enum2, Enum3};
Q_ENUMS(MyEnumeration)
};
#endif // MYCLASS_H
and myApp .pro :
TEMPLATE = app
QT += qml quick multimedia network widgets sql xml
SOURCES += main.cpp \
myapp.cpp
HEADERS += \
myapp.h
RESOURCES += qml.qrc
# Additional import path used to resolve QML modules in Qt Creator's code model
QML_IMPORT_PATH =
# Default rules for deployment.
include(deployment.pri)
win32:CONFIG(release, debug|release): LIBS += -L$$PWD/pathTo/build-MyBiblio_Qt_5_2_1/release/ -lMyBiblio
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/pathTo/build-MyBiblio_Qt_5_2_1/debug/ -lMyBiblio
INCLUDEPATH += $$PWD/pathTo/MyBiblio
DEPENDPATH += $$PWD/pathTo/MyBiblio
On myapp.cpp, I use enumeration define of the library :
MyClass::MyEnumeration
and i include "myclass.h"
i use Qt 5.2 under Windows.
Thank you for your help

Answer 1

When creating a shared library that you would like to link against, then you need to ensure that the symbols that are going to be used outside the library are properly exported when the library is created. And subsequently imported when you are linking against the library. This can be done using Q_DECL_EXPORT and Q_DECL_IMPORT
You already have the following define in your lib pro:
DEFINES += MYBIBLIO_LIBRARY
Modify your myClass.h as follows:
#if defined MYBIBLIO_LIBRARY
#define MYBIBLIO_LIBRARY_DLLSPEC Q_DECL_EXPORT
#else
#define MYBIBLIO_LIBRARY_DLLSPEC Q_DECL_IMPORT
#endif
class MYBIBLIO_LIBRARY_DLLSPEC MyClass : public QObject
{
Please, read How to create a library with Qt and use it in an application for more information.