Undefined reference to virtual thunk

Question

I got an error saying

undefined reference to 'virtual thunk to myClass::myFunction'

For a library i'm trying to create.

Here's my code :

myClass.cpp :
    #include "myClass.h"
    void myClass::myFunction() {}
    myClass::~myClass() {}

.

myClass.h :
    {inclusion guards}

    #include "myClass_global.h"

    class MY_CLASSSHARED_EXPORT myClass {
        public:
            myClass();
            virtual void myFunction();
            virtual ~myClass();
    };

.

myClass_global.h
    {inclusion guards}

    #include <QtCore/qglobal.h>

    # if degined(MY_CLASS_LIBRARY)
    #    define MY_CLASSSHARED_EXPORT Q_DECL_EXPORT
    # else
    #    define MY_CLASS Q_DECL_IMPORT
    # endif

I'm not really used to making libraries. I'm under QtCreator.

I've found that a "virtual thunk" might be a "function pointer" to something (a destructor ?) that can't be found ...

However, I haven't found anything very clear on the internet ...

It's clear you're not posting real code. `define MYCLASS_SHARED_EXPORT Q_DECL_EXPORT`? If you can't reproduce a minimal correct example that reproduces the problem, you're out of luck here. — Luchian Grigore, Mar 21 '13 at 16:03
That's auto-code from QtCreator ... Where's the problem ? I will edit if there's a problem ... — , Mar 21 '13 at 16:04
Gurgh ... seems like the problem is a mismatch configuration version between GCC. I'm trying to compile the library with a more recent version than another library has been compiled with. — , Mar 22 '13 at 08:32

score 2 · Answer 1 · answered Mar 04 '20 at 09:30

2

The problem is a mismatch configuration version between GCC.

The library I consumed was compiled with GCC 5.4, but I was using GCC 7.4.

When I use the GCC same as the library to compile my code, this weird linking issue is gone!

answered Mar 04 '20 at 09:30

Yifei Wu

41
5

score 2 · Answer 2 · answered Jan 12 '21 at 14:59

2

Maybe it will help somebody in the future.. For me the problem was caused by a declaration of a virtual function in class that derives from the base abstract class (inside .hpp file) but there was no definition of the function in .cpp file.

answered Jan 12 '21 at 14:59

S.Seba

121
1
11

score 0 · Answer 3 · answered Mar 21 '13 at 20:34

0

I did notice that the constructor has not been implemented. Could this be causing the issue?

answered Mar 21 '13 at 20:34

by.axiom

51
3

I think it is ... I just misspelled that ... I'm correcting. And I still got that issue ... – Mar 22 '13 at 08:32

Undefined reference to virtual thunk

3 Answers3