undefined reference to `vtable for shutdown'

J.Hilk

I'm sorry to say it, but I'm out of ideas. My experience with cmake is very limited and does not reach further :(

SPlatten

@J-Hilk , thanks for your time and efforts.

JoeCFD

@SPlatten in your source dir where cmake file is located do the following:
mkdir build
cd build
cmake .. -Dyour settings
make -j4

Try to build your code in the build folder all the time. In case you have your vtable issues, simply rm -rf * to delete everything in build dir and redo cmake. Do this only in build dir. Be very careful with rm -rf *. You have to have svn or git for your sources.

SPlatten

@JoeCFD , thank you, will give this a go now, I've been doing the following:

Delete build folder
Create build folder
From build folder cmake ${myvariable}
From build folder make

I will try using -j4 on the make.

JonB

@SPlatten
Well make -j4 isn't going to fix anything :)

Your code looks right to me (especially the Q_OBJECT, whose absence/change can often cause this). Given that you say you have cleaned everything out and rebuilt I am not sure what is wrong (unless there is some artefact left around somewhere it is still seeing).

From the linker messages undefined reference to vtable for 'shutdown' I am unsure whether it is talking about your class shutdown : public QMainWindow { or the Qt-Designer-generated namespace Ui { class shutdown; } (Ui::shutdown). You might just check what is in the generated ui_shutdown.h file to see if it looks good.... (and if that has not been being regenerated, delete it or update the .ui file to make it regenerate, just in case).

SPlatten

@JoeCFD , same result.

SPlatten

@JonB , thank you, here is ui_shutdown.h:

#ifndef UI_SHUTDOWN_H
#define UI_SHUTDOWN_H

#include <QtCore/QVariant>
#include <QtGui/QAction>
#include <QtGui/QApplication>
#include <QtGui/QButtonGroup>
#include <QtGui/QHeaderView>
#inlcude <QtGui/QLabel>
#include <QtGui/QMainWindow>
#include <QtGui/QWidget>

QT_BEGIN_NAMESPACE

class Ui_shutdown
{
public:
    QWidget *centralWidget;
    QLabel *plblText;

    void setupUi(QMainWindow *shutdown)
    {
        if ( shutdown->objectName().isEmpty())
            shutdown->setObjectName(QString::fromUtf8("shutdown"));
        shutdown->resize(171, 73);
        shutdown->setStyleSheet(QString::fromUtf8("background-color: #0790ff;\n"
"color:#ffffff;\n"
""));
        centralWidget = new QWidget(shutdown);
        centralWidget->setObjectName(QString::fromUtf8("centralWidget"));
        plblText = new QLabel(centralWidget);
        plblText->setObjectName(QString::fromUtf8("plblText"));
        plblText->setGeometry(QRect(0, 0, 171, 71));
        plblText->setStyleSheet(QString::fromUtf8("vertical-align:middle;\n"
"text-align: center;\n"
"font-weight: bold;\n"
""));
        plblText->setAlignment(Qt::AlignCenter);
        shutdown->setCentralWidget(centralWidget);

        retranslateUi(shutdown);

        QMetaObject::connectSlotsByName(shutdown);
    } // setupUi

    void retranslateUi(QMainWindow *shutdown)
    {
        shutdown->setWindowTitle(QString());
        plblText->setText(QApplication::translate("shutdown", "Shutting down...", 0, QApplication::UnicodeUTF8));
    }  // retranslateUi
};

namespace Ui {
    class shutdown: public Ui_shutdown {};
} // namespace Ui

QT_END_NAMESPACE

#endif // UI_SHUTDOWN_H

JonB

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

../../(shutdown.cc.o): In function `shutdown::shutdown(char const*, QWidget*)':

Note that this .o file is being found in ../.. from where you are/the compiler is being run. Is that indeed correct for you, and where you have deleting files from? Do you by any chance have any other shutdown.cc.o file lying around anywhere from, say, the whole of ../.. downward?

I have no experience of " I have added a class one of the libraries which are built with cmake". But when you do a complete rebuild I am expecting you to see among the commands:

A uic run on on shutdown.ui, producing ui_shutdown.h.
A cc (or whatever) compilation run on shutdown.cc, producing shutdown.o.
A cc on moc_shotdown.cc, or similar, producing <can't recall>.
Some kind of ld (or maybe cc) doing the linking. It will involve shutdown.cc.o, I can't remember how moc works, whether there is a moc_shutdown.cc.o or just the moc_shutdown.h or whatever source file.

This is not for you to paste the whole output here, it's for you to look at just to verify. It ought be correct anyway.

JoeCFD

@SPlatten ~shutdown() has to be virtual. It is better to start with upper case in your class name(Shutdown). Normally function starts with lower case.
also make sure shutdown.cpp is added to cmake file

    explicit shutdown(const char* cpszText, QWidget* pParent = 0);
    virtual ~shutdown();

JonB

@JoeCFD

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

@J-Hilk . that was the entire class, I've added virtual to the destructor prototype, rebuilding now.

@SPlatten
Let's be clear: you are now compiling with

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

right?

JoeCFD

@JonB I did not see that one. Could be the case he changed it and did not save it.

SPlatten

@JonB , the only place the shutdown.cc.o exists is off the build directory which I am still deleting completely between rebuilds.

SPlatten

@JonB , I've changed these prototypes several times with the same result each time, presently they are:

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

JoeCFD

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

JonB

@SPlatten
I am lost at this point. It might be that one of the experts knows better than I what situation you are in. You would have to wait for them to see this, perhaps later.

At this point, if I were you and I had nothing else to do I would probably take what you have and put it into a brand new, from scratch, standalone tiny project (maybe get rid of the .ui file too) and see if I could get it working as (a) a standalone Qt program (provide a main()) and (b) whatever you are doing for " I have added a class [to] one of the libraries" which I don't know about.

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

I do think you should write virtual ~shutdown(); here, just in case.

SPlatten

@JoeCFD , ok, I've changed the constructor so it is prefixed with explicit and the destructor with virtual which goes back to how it was and I still have the same issue.

SPlatten

@JonB , I believe this issue is because the build process is using just cmake and hasn't been done with Qt Creator. I can't change it, its an old system that is evolving over time.

SPlatten

Just for completeness, here is the actual content of the CMakeLists.txt file:

cmake_minimum_required(VERSION 2.8.10)
include (flexelint) 

set (CMAKE_AUTOUIC ON)
set (CMAKE_AUTOMOC ON)
set (CMAKE_AUTORCC ON)
set (CMAKE_INCLUDE_CURRENT_DIR ON)

set (FORMS shutdown_ui)
set (HEADERS shutdown.h
             ui_shutdown.h)
set (sources shutdown.cc)
set (output vip_backend)
add_library(${output} STATIC ${sources})
find_package(Qt4 REQUIRED)
include(${QT_USE_FILE})
foreach(loop_var ${QT_LIBRARIES})
  string(REPLACE lib64 lib32 loop_var ${loop_var})
  set(QT_LIBRARIES_32 ${QT_LIBRARIES_32} ${loop_var})
endforeach(loop_var)
qt4_wrap_ui(UI_HEADERS ${FORMS})
qt4_wrap_cpp(MOC_SRCS ${HEADERS})
target_link_libraries(${output} ${QT_LIBRARIES_32})
add_flint(${output})

I have no idea what flexelint is or what it does, same is true of add_flint(${output}).

JoeCFD

@SPlatten forget about Qt Creator. Try to build it from command line
Delete build folder
Create build folder
From build folder cmake ${myvariable}
From build folder make VERBOSE=1
add verbose to see more build details.

SPlatten

@JoeCFD , that is exactly all I am doing. Also cmake is version 2.8.10.2

rm -R build
mkdir build
cd build
cmake ${myvariable}
make

In the CMakeLists.txt file I have:

set (CMAKE_VERBOSE_MAKEFILE ON)