undefined reference to `vtable for shutdown'

[JoeCFD]

@SPlatten Jesus, your cmake is old.

[SPlatten]

@JoeCFD , its very frustrating, its very unusual to find a company these days that are so behind on revisions.

[JoeCFD]

@SPlatten
rm -R build
mkdir build
cd build
cmake ${myvariable}
make VERBOSE=1

[SPlatten]

@JoeCFD , doing that now.

[JoeCFD]

@SPlatten As Jon commented, you can comment the destructor code out and build. It is a small leak. Not a big deal. shutdown is not a good name for class. Try to avoid to use any system command names as your class names. Name it for example ShutdownWindow.

[SPlatten]

@JoeCFD , will try this now.

[SPlatten]

@JoeCFD , output has changed:

../../(usage.cc.o): In function 'shutdownNotice(char cont*)':
vip_system.cc:(.text+0xe1): undefined reference to `vtable for shutdown'
vip_system.cc:(.text+0xe9): undefined reference to `vtable for shutdown'
vip_system.cc:(.text+0x100): undefined reference to `vtable for shutdown'
vip_system.cc:(.text+0x108): undefined reference to `vtable for shutdown'
../../(shutdown.cc.o): In function 'shutdown::shutdown(char cont*, QWidget*)':
shutdown.cc:(text+0x3a): undefined reference to `vtable for shutdown'
../../(shutdown.cc.o):shutdown.cc(.text+0x41): more undefined references to `vtable for shutdown' follow collect2 ld returned 1 exit status

[JoeCFD]

are you building on Linux, right? If yes, change your class name with ShutdownWindow (do not forget the ui file).

[SPlatten]

@JoeCFD , yes Linux...will give it a go (renaming I mean).

[SPlatten]

@JoeCFD, I've changed the class names, do the filenames also need to be changed?

[JoeCFD]

@SPlatten better. But not necessary. Try to build to see if it works.

[SPlatten]

@JoeCFD , I was hoping this was going to solve the problems, but sadly not, the reports messages are the same just "shutdownWindow" now instead of "shutdown".

[JoeCFD]

@SPlatten something weird is going here. This means you can not add any class to your project. You must have other classes. Copy it and change its name to ShutdownWindow. Add it to your project. May I see your
make VERBOSE=1 output?

[SPlatten]

@JoeCFD , could this be a namespace / scope issue? I don't have a lot of experience with namespace and the pitfalls of use.

The C module where these are used are defined in:

namespace a {
namespace b {
namespace c {
static void shutdownNotice(const char* cpszText) {
    shutdownWindow w(cpszText);
    w.setWindowFlags(Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint);
    w.move(QApplication::desktop()->screen()->rect().center() - w.frameGeometry().center());
    w.show();
}
...

In the shutdown.h and shutdown.cc files there are no namespaces except in the header:

namespace Ui {
    class shutdownWindow;
}

[Christian Ehrlicher]

@SPlatten said in undefined reference to `vtable for shutdown':

set (HEADERS shutdown.h
ui_shutdown.h)

ui_shutdown.h must not be here. And there must not be such a header file in the source directory!

qt4_wrap_ui(UI_HEADERS ${FORMS})
qt4_wrap_cpp(MOC_SRCS ${HEADERS})

This does nothing as long as you don't add the output (UI_HEADERS, MOC_SRCS) to your add_library() call ...

set (FORMS shutdown_ui)

I doubt this is correct.

You have always to have virtual in front of a destructor. Otherwise, you may have unpleasant memory leak in your apps.

This is wrong - the shutdown dtor is virtual by default because QObject's dtor is already virtual

[SPlatten]

I'm now pretty sure the problem is namespace related, but I don't know how to resolve it.

In the source file where the static function shutdownNotice is called it is inside three levels of namespace:

#include "shutdown.h"
#include <QApplication>
#include <QDesktopWidget>

namespace a {
namespace b {
namespace c {

static void shutdownNotice(const char* cpszText) {
    Ui::shutdownWindow w(cpszText);
    w.setWindowFlags(Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint);
    w.move(QApplication::desktop()->screen()->rect().center()
           - w.frameGeometry().center());
    w.show();
}
...

In the header that contains the shutdownWindow class:

shutdown.h:

#ifndef SHUTDOWN_H
#define SHUTDOWN_H

#include <QMainWindow>

namespace Ui {
    class shutdownWindow;
}

class shutdownWindow : public QMainWindow {
    Q_OBJECT

public:
    explicit shutdownWindow(const char* cpszText, QWidget* pParent = 0);
    ~shutdownWindow();

private:
    Ui::shutdownWindow* ui;
};
#endif // SHUTDOWN_H

shutdown.cc

#include "shutdown.h"
#include "ui_shutdown.h"

shutdownWindow::shutdownWindow(const char* cpszText, QWidget* pParent) :
    QMainWindow(pParent),
    ui(new Ui::shutdownWindow) {
    ui->setupUi(this);
    if ( cpszText ) {
        ui->plblText->setText(cpszText);
    }
}

shutdownWindow::~shutdownWindow() {
    delete ui;
}

With this set-up, the errors are:

In function 'void a::b::c::shutdownNotice(const char*)':
error: variable `Ui::shutdownWindow w' has initializer but incomplete type

[SGaist]

You did not include the required file.

That said, you are using it wrongly. It's not Ui::shutdownWindow that you want to instantiate but just shutdownWindow.

[SPlatten]

@SGaist , where? what line? because I believe the Ui::shutdownWindow is just used as a forward declaration, also this code was copied from an auto generated header and source file by Qt Creator...create a blank UI class in Qt Creator with a single label, removing the menu and status bar and this is pretty much what you get.

Just to complete the picture the gcc version is Gentoo 4.6.3 p1.13, pie-0.5.2)

[SPlatten]

I finally found and fixed the issue, which turned out to be not code related at all. The problem was in the CMakeLists.txt file, the build structure here is over complicated and there were two instances of the same file in a slightly different folder structure, unfortunately I had been editing the wrong file, having realised this and moved onto the correct file, everything is now A ok!

[JonB]

@SPlatten

@JonB said in undefined reference to `vtable for shutdown':

Do you by any chance have any other shutdown.cc.o file lying around anywhere from, say, the whole of ../.. downward?

You really might have spotted a duplicate shutdown.cc while checking for this.

And/or, when you were recompiling each time the Compilation Output (or whatever) pane shows you the build commands being executed, could you not see this situation from that?