Undefined reference to vtable

[Matthias Kaeppler]

Hi,

I'm confronted with an error here I haven't encountered before (g++ 3.3.5):

Building duality.elf ...
obj_dbg/mainwindow.o(.g nu.linkonce.t._ ZN14TransferDia logC1EN5boost10 shared_ptrI4Tas kEE+0x5c):
In function
`TransferDialog ::TransferDialo g[in-charge](boost::shared_ ptr<Task>)':
/usr/include/c++/3.3/bits/sstream.tcc:57: undefined reference to `vtable
for TransferDialog'
collect2: ld returned 1 exit status
make: *** [duality.elf] Error 1

It seems to come from this class' ctor:

class TransferDialog: public TaskDialog
{
public:
TransferDialog( TaskPtr task_ptr): TaskDialog(task _ptr) {}
virtual int on_progress_upd ate(
const Gnome::Vfs::Asy nc::Handle&,
Gnome::Vfs::Tra nsfer::Progress Info&);
virtual bool on_progress_syn c(
const Gnome::Vfs::Tra nsfer::Progress Info&);
};

here's the base class:

class TaskDialog
{
public:
TaskDialog(Task Ptr task_ptr): task_(task_ptr) {}
virtual ~TaskDialog() {}
virtual int on_progress_upd ate(
const Gnome::Vfs::Asy nc::Handle&,
Gnome::Vfs::Tra nsfer::Progress Info&);
virtual bool on_progress_syn c(
const Gnome::Vfs::Tra nsfer::Progress Info&);
protected:
TaskPtr get_task() const;
private:
TaskPtr task_;
};

TaskPtr is merely a typedef for boost::shared_p tr<Task>. I don't think
the Task class matters here, but if you want me to post it I can surely
do that as well.

It almost looks as if a virtual function is being invoked in the ctor
before the vtable exists, but on the other hand, that's not the case, as
far as I can tell. I don't know what is causing this.

Thanks in advance,
Matthias

[Kristo]

Matthias Kaeppler wrote:

Hi,

I'm confronted with an error here I haven't encountered before (g++ 3.3.5):

Building duality.elf ...
obj_dbg/mainwindow.o(.g nu.linkonce.t._ ZN14TransferDia logC1EN5boost10 shared_ptrI4Tas kEE+0x5c):
In function
`TransferDialog ::TransferDialo g[in-charge](boost::shared_ ptr<Task>)':
/usr/include/c++/3.3/bits/sstream.tcc:57: undefined reference to `vtable
for TransferDialog'
collect2: ld returned 1 exit status
make: *** [duality.elf] Error 1

As this is a *linker* error, you're probably better off asking this on
a GCC mailing list. In addition to that, the GCC FAQ
(http://gcc.gnu.org/faq.html#vtables) has an entry that might be of
use.

Kristo

[Gabriel]

Matthias Kaeppler wrote:

Hi,

I'm confronted with an error here I haven't encountered before (g++ 3.3.5):

/usr/include/c++/3.3/bits/sstream.tcc:57: undefined reference to `vtable
for TransferDialog'

That is the most obscure error message the gcc produces, but the reason
is usually simple:

The compiler has to put the vtable into an object file. It puts it into
the object file where the definition of the first non-inline member
function is. If it is missing, you get this rather unhelpful linker
error. Please check the existence of the definitions of your member
functions.

Gabriel

[Matthias Kaeppler]

Gabriel wrote:

The compiler has to put the vtable into an object file. It puts it into
the object file where the definition of the first non-inline member
function is. If it is missing, you get this rather unhelpful linker
error. Please check the existence of the definitions of your member
functions.

Argh, you're right. I didn't provide an implementation for one of the
two methods in the subclass, but I declared it in the subclass. I just
removed the declaration so that the default implementation of the base
class will be used, which is what I want at this point.

Thanks,
Matthias

--
Matthias Kaeppler