Undefined refence to "main"

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.

R.griset

@Christian-Ehrlicher when I define src as a library I get

/usr/bin/ld: cannot find -lmyapp
Makefile:127: recipe for target 'app' failed
make[1]: Leaving directory '/home/d07876/Desktop/Ancrage/Code interface graphique ancrage/build-anchorage-QT5-Debug/app'
Makefile:68: recipe for target 'sub-app-make_first' failed
collect2: error: ld returned 1 exit status
make[1]: *** [app] Error 1
make: *** [sub-app-make_first] Error 2
15:01:17: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project anchorage (kit: QT5)
When executing step "Make"

R.griset

it seems to come from the fact that line

"LIBS += -L../src -lmyapp" in app.pro file is not recognize when src.pro is define as a library

SGaist

As already pointed out earlier, your project, as it is can not compile.

As for your LIBS statement, the library is generated in the shadow build folder, not in your sources where you are pointing it to. Use the OUT_PWD variable as starting folder.

R.griset

Hello SGaist and merry Christmas,

Thanks again for your help but once again I can't figure out what you want me to do exactly. So here is how I understood your advice :

As you told me in one of your first post I need to set "TEMPLATE = lib" instead of "TEMPLATE = app" in my src.pro file
Now when I compile the compiler doesn't find -lmyapp (by the way I don't know if "myapp" is a generic name ) because in my app.pro file I point to ../src in line "LIBS += -L../src -lmyapp"
Instead of ../src I tried $OUT_PWD or $OUT_PWD/src but the compiler still doesn't find -lmyapp :(

I guess I didn't understand your post