Qt + CMake no moc files genereated

ceora

Hi, I'm trying to build a simple QCoreApplication prorgam using CMake as a project files.
At time of building I get link error to Qt meta, the ones that shoul be generated with moc.

I followed the documentation on cmake and qt on how to set up a project, but Automoc does'nt work

this is my cmake file:

project(CMake_Test2)
cmake_minimum_required(VERSION 2.8)

aux_source_directory(. SRC_LIST)

find_package(Qt5 COMPONENTS core REQUIRED)
set(CMAKE_AUTOMOC ON)
set(CMAKE_INCLUDE_CURRENT_DIR ON)

add_executable(${PROJECT_NAME} ${SRC_LIST})

target_link_libraries(${PROJECT_NAME} Qt5::Core)

the source files are a simple helloworld main.cpp file and two files containing a simple QObject
definition and declaration(just to test the moc generation)

SGaist

Hi,

Following Qt's cmake manual you might be missing the set(CMAKE_INCLUDE_CURRENT_DIR ON) line in your CMakeLists.txt.

Hope it helps

ceora

Mmmh a great miss, however this was a test I made to figure out why another similar project doesn't work.. And I got the same errors, but in that project I'm pretty sure I didn't miss that line. Now I don't have the code under the eyes, but I'll let you know if it work!

SGaist

Depending on the size and complexity of the beast, you might have better luck recreating the CMakeLists.txt file from scratch and re-add stuff piece by piece until it either breaks again or just works.

ceora

i just re-read the first-post and as you can see the

set(CMAKE_INCLUDE_CURRENT_DIR ON)

is already set...

SGaist

Right, I managed to miss it...

Which version of CMake and Qt are you using ?

ceora

Cmake version 3.7.0 and Qt 5.7

SGaist

Ok, can you share the code you have to reproduce your problem ?

ceora

of corse! The cmake file is the same i posted in the previous post

test.h

#include <QObject>

class Test : public QObject
{
  Q_OBJECT
public:
  Test();
  virtual ~Test() {}
};

test.cpp

#include "test.h"

Test::Test()
{}

main.cpp

#include <iostream>
#include <QCoreApplication>
#include <QDebug>

#include "test.h"

using namespace std;

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);
  Test t;
  t.setObjectName("Test");
  qDebug() << t.objectName();

  return a.exec();
}

instead if you prefer the "real project"(the errors are pretty the same)..
github repo
to compile it you need tinyXML2. There is the working .pro file and the non working cmake file.

mchinand

Isn't moc only needed if your QObject class has signals and/or slots?

ceora

I think it's needed only the Q_OBJECT macro to activate moc, signals and slots are inherited from QObject.

SGaist

@ceora That's not the problem at hand it's the automoc not running properly.

@ceora try with:

cmake_minimum_required(VERSION 2.8.11)

project(CMake_Test2)

set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOMOC ON)

find_package(Qt5Core)

file(GLOB SOURCES *.cpp)

add_executable(${PROJECT_NAME} ${SOURCES})
target_link_libraries(${PROJECT_NAME} Qt5::Core)

ambershark

Your example and code worked fine for me with one exception. This line had to be changed to a capital C on core:

find_package(Qt5 COMPONENTS Core REQUIRED)

Here is the build output with make VERBOSE=1:

-- The C compiler identification is GNU 6.2.1
-- The CXX compiler identification is GNU 6.2.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/mike/tmp/x/build
/usr/bin/cmake -H/home/mike/tmp/x -B/home/mike/tmp/x/build --check-build-system CMakeFiles/Makefile.cmake 0
/usr/bin/cmake -E cmake_progress_start /home/mike/tmp/x/build/CMakeFiles /home/mike/tmp/x/build/CMakeFiles/progress.marks
make -f CMakeFiles/Makefile2 all
make[1]: Entering directory '/home/mike/tmp/x/build'
make -f CMakeFiles/CMake_Test2_automoc.dir/build.make CMakeFiles/CMake_Test2_automoc.dir/depend
make[2]: Entering directory '/home/mike/tmp/x/build'
cd /home/mike/tmp/x/build && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/mike/tmp/x /home/mike/tmp/x /home/mike/tmp/x/build /home/mike/tmp/x/build /home/mike/tmp/x/build/CMakeFiles/CMake_Test2_automoc.dir/DependInfo.cmake --color=
Dependee "/home/mike/tmp/x/build/CMakeFiles/CMake_Test2_automoc.dir/DependInfo.cmake" is newer than depender "/home/mike/tmp/x/build/CMakeFiles/CMake_Test2_automoc.dir/depend.internal".
Dependee "/home/mike/tmp/x/build/CMakeFiles/CMakeDirectoryInformation.cmake" is newer than depender "/home/mike/tmp/x/build/CMakeFiles/CMake_Test2_automoc.dir/depend.internal".
Scanning dependencies of target CMake_Test2_automoc
make[2]: Leaving directory '/home/mike/tmp/x/build'
make -f CMakeFiles/CMake_Test2_automoc.dir/build.make CMakeFiles/CMake_Test2_automoc.dir/build
make[2]: Entering directory '/home/mike/tmp/x/build'
[ 20%] Automatic moc for target CMake_Test2
/usr/bin/cmake -E cmake_autogen /home/mike/tmp/x/build/CMakeFiles/CMake_Test2_automoc.dir/ ""
AUTOGEN: Checking /home/mike/tmp/x/main.cpp
AUTOGEN: Checking /home/mike/tmp/x/test.cpp
AUTOGEN: Checking /home/mike/tmp/x/test.h
Generating moc source moc_test.cpp
/usr/local/Qt/bin/moc -I/home/mike/tmp/x/build -I/home/mike/tmp/x -I/usr/local/Qt/include -I/usr/local/Qt/include/QtCore -I/usr/local/Qt/./mkspecs/linux-g++ -DQT_CORE_LIB -DQT_NO_DEBUG -o /home/mike/tmp/x/build/moc_test.cpp /home/mike/tmp/x/test.h
Generating moc compilation CMake_Test2_automoc.cpp
make[2]: Leaving directory '/home/mike/tmp/x/build'
[ 20%] Built target CMake_Test2_automoc
make -f CMakeFiles/CMake_Test2.dir/build.make CMakeFiles/CMake_Test2.dir/depend
make[2]: Entering directory '/home/mike/tmp/x/build'
cd /home/mike/tmp/x/build && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/mike/tmp/x /home/mike/tmp/x /home/mike/tmp/x/build /home/mike/tmp/x/build /home/mike/tmp/x/build/CMakeFiles/CMake_Test2.dir/DependInfo.cmake --color=
Dependee "/home/mike/tmp/x/build/CMakeFiles/CMake_Test2.dir/DependInfo.cmake" is newer than depender "/home/mike/tmp/x/build/CMakeFiles/CMake_Test2.dir/depend.internal".
Dependee "/home/mike/tmp/x/build/CMakeFiles/CMakeDirectoryInformation.cmake" is newer than depender "/home/mike/tmp/x/build/CMakeFiles/CMake_Test2.dir/depend.internal".
Scanning dependencies of target CMake_Test2
make[2]: Leaving directory '/home/mike/tmp/x/build'
make -f CMakeFiles/CMake_Test2.dir/build.make CMakeFiles/CMake_Test2.dir/build
make[2]: Entering directory '/home/mike/tmp/x/build'
[ 40%] Building CXX object CMakeFiles/CMake_Test2.dir/main.cpp.o
/usr/bin/c++   -DQT_CORE_LIB -DQT_NO_DEBUG -I/home/mike/tmp/x/build -I/home/mike/tmp/x -isystem /usr/local/Qt/include -isystem /usr/local/Qt/include/QtCore -isystem /usr/local/Qt/./mkspecs/linux-g++  -fPIC -std=gnu++11 -o CMakeFiles/CMake_Test2.dir/main.cpp.o -c /home/mike/tmp/x/main.cpp
[ 60%] Building CXX object CMakeFiles/CMake_Test2.dir/test.cpp.o
/usr/bin/c++   -DQT_CORE_LIB -DQT_NO_DEBUG -I/home/mike/tmp/x/build -I/home/mike/tmp/x -isystem /usr/local/Qt/include -isystem /usr/local/Qt/include/QtCore -isystem /usr/local/Qt/./mkspecs/linux-g++  -fPIC -std=gnu++11 -o CMakeFiles/CMake_Test2.dir/test.cpp.o -c /home/mike/tmp/x/test.cpp
[ 80%] Building CXX object CMakeFiles/CMake_Test2.dir/CMake_Test2_automoc.cpp.o
/usr/bin/c++   -DQT_CORE_LIB -DQT_NO_DEBUG -I/home/mike/tmp/x/build -I/home/mike/tmp/x -isystem /usr/local/Qt/include -isystem /usr/local/Qt/include/QtCore -isystem /usr/local/Qt/./mkspecs/linux-g++  -fPIC -std=gnu++11 -o CMakeFiles/CMake_Test2.dir/CMake_Test2_automoc.cpp.o -c /home/mike/tmp/x/build/CMake_Test2_automoc.cpp
[100%] Linking CXX executable CMake_Test2
/usr/bin/cmake -E cmake_link_script CMakeFiles/CMake_Test2.dir/link.txt --verbose=1
/usr/bin/c++      CMakeFiles/CMake_Test2.dir/main.cpp.o CMakeFiles/CMake_Test2.dir/test.cpp.o CMakeFiles/CMake_Test2.dir/CMake_Test2_automoc.cpp.o  -o CMake_Test2 -rdynamic /usr/local/Qt/lib/libQt5Core.so.5.7.0 -Wl,-rpath,/usr/local/Qt/lib
make[2]: Leaving directory '/home/mike/tmp/x/build'
[100%] Built target CMake_Test2
make[1]: Leaving directory '/home/mike/tmp/x/build'
/usr/bin/cmake -E cmake_progress_start /home/mike/tmp/x/build/CMakeFiles 0

Again this used your test.h/cpp and main.cpp, as well as your posted CMakeFiles.txt. I used cmake 3.6.2 and Qt 5.7 for the test if that matters (it shouldn't).

SGaist

@ambershark Nice catch ! I missed that one.

On a side note, aux_source_directory as used in the sample code goes against the CMake recommandation.

ambershark

@SGaist Oh I would have missed it too if I didn't try to run his example. Case stuff is hard to see without a compiler issue. :)

SGaist

I also ran it but I didn't saw anything about the component itself but I may have very well missed it.

ceora

Tried both solutions: And both work! It seems that the capital c on core make the difference, now moc is triggered correctly. It work also for the "real project".

Thanks guys!!