Undefined refence to "main"

SGaist

Hi,

You tell in your src.pro that the template is an application however, you don't provide any main function hence the error.

If you want to reuse what you have in src in your app then you should make it a library and link to that library.

R.griset

Hello SGaist and thanks for your help,
Unfortunately I don't get what I should do precisely from your message. This application works as is on an other computer I'm just trying to rebuild it on a different environment.

SGaist

Then you should explain what you are currently expecting to build from that src project.

R.griset

I'm trying to build an executable which is an interface using widgets. Sorry if my answers are not clear I usually uses cmake and not qmake so I'm not used to those .pro files and this structure of project.

SGaist

Well, if you are used to cmake, you can continue using it. There's no need to switch over to qmake especially since Qt 6 build system will be cmake.

You can find here the CMake manual for Qt projects.

However, if you really want to use qmake, then from the structure you are showing it seems that you would like to have:

One application project which is app
One library project which is src (and that you are currently trying to build as an app)

Based on the test folder, it seems that you would like to do some unit testing (which is very good) so do you want to test your application or your library ?

R.griset

Hello SGaist,

I think I need to give you more detail about the project. So I have a first computer where this project is build as if (so with the src part building as an application and not as a library) using QT creator. On this computer we just load the project by opening MainPro.pro, compute it and launch it inside QT creator.

Now on my computer I'm trying to do the same thing. The test folder is indeed a unit testing used to test so algorithms from the src part. In QT creator i get some errors so I tried first to compile outside using qmake. I'll try to solve those errors directly inside Qt creator as compiling outside of it seemed to be a bad idea. I'll let you know if I can find what s wrong.

Thanks again for your help

R.griset

It seems that the issue might just be cause by the fact dataChanged is not recognize, I tried to add QT+=core in my .pro files but it doesn't solve the issue

R.griset

So in some files I have a line :
emit dataChanged(index,index, {Qt::DisplayRole, Qt::EditRole});
and the dataChanged function doesn't seem to accept the third argument

R.griset

Additionnally I get :

no matching function for call to ‘SolutionPoolModel::connect(SolutionPoolModel*, void (QAbstractItemModel::)(const QModelIndex&, const QModelIndex&), SolutionPoolModel::SolutionPoolModel(ParametersSet, QObject*)::<lambda(const QModelIndex&, const QModelIndex&, const QVector<int>&)>)’

     connect(this, &SolutionPoolModel::dataChanged, [this](const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector<int> &roles){Q_UNUSED(topLeft) Q_UNUSED(bottomRight) Q_UNUSED(roles) this->updateMakespanBoundaries();});
                                                                                                                                                                                                                                            ^

JonB

@R-griset
Although these can be addressed, do you know what version of Qt, and possibly what version of which compiler, this code has been developed using?

Christian Ehrlicher

@R-griset said in Undefined refence to "main":

void (QAbstractItemModel::)(const QModelIndex&, const QModelIndex&),

This is Qt4 ... you mix Qt4 and Qt5 include files.

R.griset

Ok thanks to your advices I switched the Qt version used to build from 4 to 5 (this code has been developed with QT5 )

However I'm still ahving the error

R.griset

I think the error probably comes from the fact qmake is called with -qt4 option but I can't figure out how to change it

Christian Ehrlicher

Select the correct qmake for the correct Qt5 kit under 'Qt versions'

R.griset

Hello Christian Ehrlicher and thanks for helping

Ok i changed the kit but now i'm getting back to my initial issue which I encountered outside of Qt creator : the undefined reference to main :(

13:35:55: Running steps for project anchorage...
13:35:55: Configuration unchanged, skipping qmake step.
13:35:55: Starting: "/usr/bin/make"
cd src/ && ( test -e Makefile || /usr/lib/x86_64-linux-gnu/qt5/bin/qmake /home/d07876/Desktop/Ancrage/Code\ interface\ graphique\ ancrage/UI_11_05/src/src.pro -spec linux-g++-64 CONFIG+=debug CONFIG+=qml_debug -o Makefile ) && /usr/bin/make -f Makefile
make[1]: Entering directory '/home/d07876/Desktop/Ancrage/Code interface graphique ancrage/build-anchorage-QT5-Debug/src'
g++ -m64 -o src heuristics.o longest_paths.o manual_modification.o metaheuristics.o resource_flow_computation.o resource_flow_modifications.o data_models.o data_structures.o resource_flow.o parsing.o writing.o central_widget.o central_widget_solution_tab.o gantt_view.o mainwindow.o parameters_bar.o parameters_edition_dialog.o resource_view.o sidebar.o sidebar_list.o solution_pool_view.o moc_data_models.o moc_central_widget.o moc_central_widget_solution_tab.o moc_gantt_view.o moc_mainwindow.o moc_parameters_bar.o moc_parameters_edition_dialog.o moc_resource_view.o moc_sidebar.o moc_sidebar_list.o moc_solution_pool_view.o -L/usr/X11R6/lib64 -lQt5Widgets -lQt5Gui -lQt5Core -lGL -lpthread
/usr/lib/gcc/x86_64-linux-gnu/6/../../../x86_64-linux-gnu/Scrt1.o: In function _start': (.text+0x20): undefined reference to main'
Makefile:228: recipe for target 'src' failed
make[1]: Leaving directory '/home/d07876/Desktop/Ancrage/Code interface graphique ancrage/build-anchorage-QT5-Debug/src'
Makefile:43: recipe for target 'sub-src-make_first' failed
collect2: error: ld returned 1 exit status
make[1]: *** [src] Error 1
make: *** [sub-src-make_first] Error 2
13:35:56: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project anchorage (kit: QT5)
When executing step "Make"
13:35:56: Elapsed time: 00:01.

aha_1980

@R-griset please remove all build artifacts and build again.

Regards

Christian Ehrlicher

In your src.pro you tell qmake that you want to build an application but you do not provide a main() function there (I would guess)

R.griset

@Christian-Ehrlicher but this exact code work perfectly on an other computer so there should be a setting which doesn't need a main function there

Christian Ehrlicher

@R-griset said in Undefined refence to "main":

so there should be a setting which doesn't need a main function there

Yes, don't tell qmake that you want to create an application... an application needs a main.

R.griset

When I do so i.e replacing TEMPLATE = app by TEMPLATE = lib in the src.pro file , it leads to other errors.

In an other computer it work with TEMPLATE = app without this "undefined reference to main" issue so I'm looking for an explanation about how QT creator build the project in the other computer.