CODEWITHSUNDEEP
c++qml
JaM
JaM

Reputation: 709

QQmlEngine and cmake

I have trouble including QQmlEngine into a cmake project.

Here is my C++:

#include <QtQml/QQmlEngine>
...
QObject *someQObject;
QQmlEngine::setObjectOwnership(someQObject, QQmlEngine::ObjectOwnership::CppOwnership);

And the cmake part:

find_package(Qt5Core REQUIRED)
find_package(Qt5Gui REQUIRED)
find_package(Qt5Qml REQUIRED)
find_package(Qt5Quick REQUIRED)
...
add_executable(name ${src})
qt5_use_modules(name Core Gui Qml Quick )

Compilation fails with:

CMakeFiles/....cpp.o: In function `...':
....cpp:57: undefined reference to `QQmlEngine::setObjectOwnership(QObject*, QQmlEngine::ObjectOwnership)'
clang-3.8: error: linker command failed with exit code 1 (use -v to see invocation)

What am I missing?

Edit, @qCring (Sorry, can't comment your answer):

Well, everything works fine when I leave out the "setObjectOwnership" call. The rest of the Qt application works fine. Thus it is actually linking somehow.

When I add your line I get 

"The plain signature for target_link_libraries has already been used with the target "name".  All uses of target_link_libraries with a target   must be either all-keyword or all-plain."

Edit:

My problem vanished somehow. I am running arch linux on x86_64.

Upvotes: 0

Views: 916

Answers (1)

qCring
qCring

Reputation: 1442

You haven't actually linked to the Qt libraries and therefore get undefined symbol errors. Both macros, find_package and qt5_use_modules just provide CMake variables from certain packages/modules. You have to link the libraries like this:

target_link_libraries(${PROJECT_NAME} PUBLIC Qt5::Core PUBLIC Qt5::Gui PUBLIC Qt5::Quick PUBLIC Qt5::Qml)

Upvotes: 1

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