Undefined reference to vtable. Compilation error in project using Qt5

Question

I've tried unsuccessfully to correct the error.

Any help would be appreciated.

After correcting another compilation bug the source code compiles to 100% but then throws an undefined reference to vtable error listed below.

Searching online for "undefined reference for vtable" returns various results.

This error appears linked with:

• compilation error by QMake and CMake (sometimes fixed by re-running make command)
• missing destructor
• Q_Object declarations made in .cpp files
• Q macros in .cpp files

Project:

https://github.com/a-ilin/vidalia

Compiler:

• CMake

Compilation Error:

[ 98%] Building CXX object src/vidalia/CMakeFiles/vidalia.dir/vidalia_autogen/PNK5WDWK6L/qrc_vidalia.cpp.o
[ 98%] Building CXX object src/vidalia/CMakeFiles/vidalia.dir/vidalia_autogen/ZY6QLEUMHC/qrc_content.cpp.o
[100%] Building CXX object src/vidalia/CMakeFiles/vidalia.dir/vidalia_autogen/O3VI4VFR3H/qrc_vidalia_i18n.cpp.o
[100%] Linking CXX executable vidalia
/usr/bin/ld: CMakeFiles/vidalia.dir/Vidalia.cpp.o: in function VidaliaNativeEventFilter::VidaliaNativeEventFilter()': Vidalia.cpp:(.text._ZN24VidaliaNativeEventFilterC2Ev[_ZN24VidaliaNativeEventFilterC5Ev]+0x1f): undefined reference to vtable for VidaliaNativeEventFilter'
collect2: error: ld returned 1 exit status
make[2]: *** [src/vidalia/CMakeFiles/vidalia.dir/build.make:2105: src/vidalia/vidalia] Error 1
make[1]: *** [CMakeFiles/Makefile2:598: src/vidalia/CMakeFiles/vidalia.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

Files that appear to be the cause of the error

https://github.com/a-ilin/vidalia/blob/alpha-qt5/src/vidalia/Vidalia.h
https://github.com/a-ilin/vidalia/blob/alpha-qt5/src/vidalia/Vidalia.cpp

Lines L112, L115, L128, L227 contain "VidaliaNativeEventFilter" in Vidalia.cpp

Code snippet
Line 109 - Line 129

/** Provides native event filtering with Qt5
 */
#if QT_VERSION >= QT_VERSION_CHECK(5, 0, 0)
class VidaliaNativeEventFilter : public QAbstractNativeEventFilter
{
public:
  VidaliaNativeEventFilter()
    : QAbstractNativeEventFilter() {}

  bool nativeEventFilter(const QByteArray& eventType, void* message, long* result);
};
#endif

/** Constructor. Parses the command-line arguments, resets Vidalia's
 * configuration (if requested), and sets up the GUI style and language
 * translation. */
Vidalia::Vidalia(QStringList args, int &argc, char **argv)
: QApplication(argc, argv)
#if QT_VERSION >= QT_VERSION_CHECK(5, 0, 0)
, _nativeEventFilter(new VidaliaNativeEventFilter())
#endif

Code snippet
Line 218 - Line 242

/** On Windows, we need to catch the WM_QUERYENDSESSION message
 * so we know that it is time to shutdown. */
#if defined(Q_OS_WIN)
#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
bool
Vidalia::winEventFilter(MSG* msg, long* result)
{
#else
bool
VidaliaNativeEventFilter::nativeEventFilter(const QByteArray& /*eventType*/, void* message, long* result)
{
  MSG* msg = (MSG*)message;
#endif

  if (msg && (msg->message == WM_QUERYENDSESSION)) {
    QApplication::quit();
  }

#if QT_VERSION < QT_VERSION_CHECK(5, 0, 0)
  return QApplication::winEventFilter(msg, result);
#else
  return false;
#endif
}
#endif