undefined reference to `vtable for shutdown'

[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 &#x60;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)

[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