CMake Undefined Reference to `QGraphicsItem:: ...

[Karlos]

Hello,

I am fairly new to CMake and C++ development and I am trying to convert a Qt Creator project to CMake so that I can use CLion for development, however I am getting an error when trying to build the project.

From what I understand the project uses Qt5::Core, Qt5::Gui and Qt5::Widgets and contains no .qrc files.

The errors returned are of the form:

CMakeFiles\zeus.dir/objects.a(TileView.cpp.obj):TileView.cpp:(.rdata$_ZTV8TileView[__ZTV8TileView]+0x8c): undefined reference to `QGraphicsItem::itemChange(QGraphicsItem::GraphicsItemChange, QVariant const&)'
CMakeFiles\zeus.dir/objects.a(TileView.cpp.obj):TileView.cpp:(.rdata$_ZTV8TileView[__ZTV8TileView]+0x90): undefined reference to `QGraphicsItem::supportsExtension(QGraphicsItem::Extension) const'
CMakeFiles\zeus.dir/objects.a(TileView.cpp.obj):TileView.cpp:(.rdata$_ZTV8TileView[__ZTV8TileView]+0x94): undefined reference to `QGraphicsItem::setExtension(QGraphicsItem::Extension, QVariant const&)'
CMakeFiles\zeus.dir/objects.a(TileView.cpp.obj):TileView.cpp:(.rdata$_ZTV8TileView[__ZTV8TileView]+0x98): undefined reference to `QGraphicsItem::extension(QVariant const&) const'
CMakeFiles\zeus.dir/objects.a(TileView.cpp.obj): In function `ZN8TileViewD1Ev':
.../src/viewer/TileView.hpp:18: undefined reference to `_imp___ZN13QGraphicsItemD2Ev'
CMakeFiles\zeus.dir/objects.a(main.cpp.obj): In function `main':
.../main.cpp:7: undefined reference to `_imp___ZN12QApplicationC1ERiPPci'
.../src/main.cpp:11: undefined reference to `_imp___ZN7QWidget13showMaximizedEv'
.../src/main.cpp:13: undefined reference to `_imp___ZN12QApplication4execEv'
.../src/main.cpp:7: undefined reference to `_imp___ZN12QApplicationD1Ev'
.../src/main.cpp:7: undefined reference to `_imp___ZN12QApplicationD1Ev'

and there is many more printed out!

The original .pro file is located here.
My attempt at a CMake file is located here.

[Christian Ehrlicher]

What compiler do you use and what Qt version (and for which compiler) did you download Qt?

[Karlos]

I am using the Windows MinGW64 i686-8.1.0-posix-dwarf-rt_v6-rev0 compiler and have installed Qt 5.15.2.

I also have these variables passed in to Cmake

-DQt5_DIR=C:\Qt\5.15.2\mingw81_64\lib\cmake\Qt5 -DCMAKE_PREFIX_PATH=C:\Qt\5.15.2\mingw81_64\lib\cmake

and linking the required yaml-cpp library with the build option -lyaml-cpp.

[Christian Ehrlicher]

@Karlos said in CMake Undefined Reference to `QGraphicsItem:: ...:

TileView.cpp.obj

This is for sure not MinGW. You can not mix MingW and MSVC libraries. Make sure you use the compiler for which you've installed Qt (msvc or mingw, you still not answered this).

[Karlos]

When installing Qt I selected "Qt 5.15.2 for MinGW 8.1.0 64-bit for desktop application development" and then installed MinGW 8.1.0 from the mingw-w64 site.

My toolchain in CLion is set up to use MinGW as the compiler. Do I need to install and use MSVC?

[jsulm]

@Karlos said in CMake Undefined Reference to `QGraphicsItem:: ...:

and then installed MinGW 8.1.0 from the mingw-w64 site

You should prefer MinGW provided by Qt installer instead.

[Karlos]

Thank you both for your swift replies. I'll update my toolchain so that it uses the MinGW compiler provided with the Qt installation. I am unavailable to reply for a few hours but will update this thread when I can.

EDIT: This worked! Many thanks!