Undefined reference to vtable

Question

So, I'm getting the infamously horrible

undefined reference to 'vtable...

error for the following code (The class in question is CGameModule.) and I cannot for the life of me understand what the problem is. At first, I thought it was related to forgetting to give a virtual function a body, but as far as I understand, everything is all here. The inheritance chain is a little long, but here is the related source code. I'm not sure what other information I should provide.

Note: The constructor is where this error is happening, it'd seem.

My code:

class CGameModule : public CDasherModule {
 public:
  CGameModule(Dasher::CEventHandler *pEventHandler, CSettingsStore *pSettingsStore, CDasherInterfaceBase *pInterface, ModuleID_t iID, const char *szName)
  : CDasherModule(pEventHandler, pSettingsStore, iID, 0, szName)
  { 
      g_pLogger->Log("Inside game module constructor");   
      m_pInterface = pInterface; 
  }

  virtual ~CGameModule() {};

  std::string GetTypedTarget();

  std::string GetUntypedTarget();

  bool DecorateView(CDasherView *pView) {
      //g_pLogger->Log("Decorating the view");
      return false;
  }

  void SetDasherModel(CDasherModel *pModel) { m_pModel = pModel; }


  virtual void HandleEvent(Dasher::CEvent *pEvent); 

 private:



  CDasherNode *pLastTypedNode;


  CDasherNode *pNextTargetNode;


  std::string m_sTargetString;


  size_t m_stCurrentStringPos;


  CDasherModel *m_pModel;


  CDasherInterfaceBase *m_pInterface;
};

Inherits from...

class CDasherModule;
typedef std::vector<CDasherModule*>::size_type ModuleID_t;

/// \ingroup Core
/// @{
class CDasherModule : public Dasher::CDasherComponent {
 public:
  CDasherModule(Dasher::CEventHandler * pEventHandler, CSettingsStore * pSettingsStore, ModuleID_t iID, int iType, const char *szName);

  virtual ModuleID_t GetID();
  virtual void SetID(ModuleID_t);
  virtual int GetType();
  virtual const char *GetName();

  virtual bool GetSettings(SModuleSettings **pSettings, int *iCount) {
    return false;
  };

 private:
  ModuleID_t m_iID;
  int m_iType;
  const char *m_szName;
};

Which inherits from....

namespace Dasher {
  class CEvent;
  class CEventHandler;
  class CDasherComponent;
};

/// \ingroup Core
/// @{
class Dasher::CDasherComponent {
 public:
  CDasherComponent(Dasher::CEventHandler* pEventHandler, CSettingsStore* pSettingsStore);
  virtual ~CDasherComponent();

  void InsertEvent(Dasher::CEvent * pEvent);
  virtual void HandleEvent(Dasher::CEvent * pEvent) {};

  bool GetBoolParameter(int iParameter) const;
  void SetBoolParameter(int iParameter, bool bValue) const;

  long GetLongParameter(int iParameter) const;
  void SetLongParameter(int iParameter, long lValue) const;

  std::string GetStringParameter(int iParameter) const;
  void        SetStringParameter(int iParameter, const std::string & sValue) const;

  ParameterType   GetParameterType(int iParameter) const;
  std::string     GetParameterName(int iParameter) const;

 protected:
  Dasher::CEventHandler *m_pEventHandler;
  CSettingsStore *m_pSettingsStore;
};
/// @}


#endif

Answer 1

For what it is worth, forgetting a body on a virtual destructor generates the following:

undefined reference to `vtable for CYourClass'.

I am adding a note because the error message is deceptive. (This was with gcc version 4.6.3.)

Answer 2

If all else fails, look for duplication. I was misdirected by the explicit initial reference to constructors and destructors until I read a reference in another post. It's any unresolved method. In my case, I thought I had replaced the declaration that used char *xml as the parameter with one using the unnecessarily troublesome const char *xml, but instead, I had created a new one and left the other one in place.

Answer 3

Not perhaps. Definitely ~CDasherModule() {} is missing.

Answer 4

There are a lot of possibilities mentioned for causing this error, and I'm sure many of them do cause the error. In my case, there was another definition of the same class, due to a duplication of the source file. This file was compiled, but not linked, so the linker was complaining about being unable to find it.

To summarize, I would say that if you've stared at the class long enough and can't see what possible syntax problem could be causing it, look for build issues like a missing file or a duplicated file.

Answer 5

I think it's also worth mentioning that you will also get the message when you try to link to object of any class that has at least one virtual method and linker cannot find the file. For example:

Foo.hpp:

class Foo
{
public:
    virtual void StartFooing();
};

Foo.cpp:

#include "Foo.hpp"

void Foo::StartFooing(){ //fooing }

Compiled with:

g++ Foo.cpp -c

And main.cpp:

#include "Foo.hpp"

int main()
{
    Foo foo;
}

Compiled and linked with:

g++ main.cpp -o main

Gives our favourite error:

/tmp/cclKnW0g.o: In function main': main.cpp:(.text+0x1a): undefined reference tovtable for Foo' collect2: error: ld returned 1 exit status

This occure from my undestanding becasue:

1. Vtable is created per class at compile time

2. Linker does not have access to vtable that is in Foo.o

Answer 6

So, I've figured out the issue and it was a combination of bad logic and not being totally familiar with the automake/autotools world. I was adding the correct files to my Makefile.am template, but I wasn't sure which step in our build process actually created the makefile itself. So, I was compiling with an old makefile that had no idea about my new files whatsoever.

Thanks for the responses and the link to the GCC FAQ. I will be sure to read that to avoid this problem occurring for a real reason.