Qt: Compare QVariable with Enum of DLL - qt

Question

I try to compare a QVariable of a QSignalSpy with a Enum in a test function. I found Q_ENUM_NS, but I got a linker error. I have rebuilt it and run qmake.
Error Message: Undefined reference to CCS::staticMetaObject
testopcua.cpp (most parts)
Q_DECLARE_METATYPE(CCS::DataManagerState)
using namespace ::testing;
class TestOpcUa : public Test
{
public:
TestOpcUa()
{
//.....
}
~TestOpcUa()
{
delete _selectedConfValid;
delete _opcUaObjectValid;
}
protected:
MockOpcConf* _selectedConfValid = nullptr;
OpcUa* _opcUaObjectValid = nullptr;
};
TEST_F(TestOpcUa, checkHandshake)
{
qRegisterMetaType<CCS::DataManagerState>("state");
QSignalSpy readySpy(_opcUaObjectValid, SIGNAL(newManagerState(CCS::DataManagerState)));
_opcUaObjectValid->connect();
readySpy.wait();
ASSERT_EQ(readySpy.count(), 1);
ASSERT_EQ(readySpy.at(0).at(0).value<CCS::DataManagerState>(), CCS::DataManagerState::Ready); //Linker error
}
int main(int argc, char *argv[])
{
QCoreApplication app(argc, argv);
testing::InitGoogleTest(&argc, argv);
testing::InitGoogleMock(&argc, argv);
return RUN_ALL_TESTS();
}
enums.h of DLL
#include <QObject>
namespace CCS
{
Q_NAMESPACE
enum class DataManagerState
{None, Configure, Ready, Active, Waiting, Stop};
Q_ENUM_NS(DataManagerState)
}

Answer 1

I think you need to add an explicit export/import directive to the QT_NAMESPACE macro.
namespace CCS
{
Q_DECL_EXPORT Q_NAMESPACE
...
}
But you'll most likely need to abstract the Q_DECL_EXPORT part so it is a Q_DECL_IMPORT in right circumstances, as described in Creating Shared Libraries (or in the Qt Wiki How to create a library with Qt...)
global.h of DLL
#include <QtCore/QtGlobal>
#if defined(MYSHAREDLIB_LIBRARY)
# define MYSHAREDLIB_EXPORT Q_DECL_EXPORT
#else
# define MYSHAREDLIB_EXPORT Q_DECL_IMPORT
#endif
enums.h of DLL
#include "global.h"
#include <QObject>
namespace CCS
{
MYSHAREDLIB_EXPORT Q_NAMESPACE
...
}
Note that if you plan to also use the "DLL" code as a statically linked lib (or directly included in other code, w/out any lib), you'll need a 3rd condition in global.h which defines MYSHAREDLIB_EXPORT as nothing.
global.h of DLL
#include <QtCore/QtGlobal>
#if defined(MYSHAREDLIB_LIBRARY)
# define MYSHAREDLIB_EXPORT Q_DECL_EXPORT
#elif defined(MYSHAREDLIB_STATIC)
# define MYSHAREDLIB_EXPORT
#else
# define MYSHAREDLIB_EXPORT Q_DECL_IMPORT
#endif
Q_DECLARE_METATYPE(CCS::DataManagerState)
Shouldn't need this.

Answer 2

Since Qt 5.14 you can use Q_NAMESPACE_EXPORT macro.
https://doc.qt.io/qt-5/qobject.html#Q_NAMESPACE_EXPORT
namespace CSS
{
Q_NAMESPACE_EXPORT(MYSHAREDLIB_LIBRARY)
...
}