Port to CMake

[PureTryOut]

qmake won't be developed anymore from Qt6 and they're switching to CMake, so let's do the same.

Should be functionally the same as with qmake (compiles for me both with and without mlite5 anyway), but you can now build with:

cmake
make
make install

[PureTryOut]

I've tested this as a dependency of a qmake project (the quickcontrols-nemo examples) and as a dependency of a CMake project (glacier-calc with this PR), and both compile and run fine.

[PureTryOut]

@neochapay I've re-added qdeclarative-boostable. However, I can not test it myself, so someone else needs to do it. I can only test the "not found" path 😉

[Kaffeine]

Please consider the modern approach with target names containing double colons, properly set up target_link_libraries() with proper PRIVATE/PUBLIC/INTERFACE linkage, add an alias target with double colons, etc.
I would suggest to use Glacier::App for this library and reserve the place for other components to be added later.

Consider an application linking as follow:

target_link_libraries(${PROJECT_NAME}
   glacierapp
)

glacierapp can be anything and in case of missing CMake target, the build system will link against libglacierapp happily ignoring the absence of linking information. You're going to have the same issue as we had with TelepathyQt. :-(

[PureTryOut]

Thanks @Kaffeine! I'm still new to CMake so I'm learning while doing 😉

Please consider the modern approach with target names containing double colons, properly set up target_link_libraries() with proper PRIVATE/PUBLIC/INTERFACE linkage, add an alias target with double colons, etc.
I would suggest to use Glacier::App for this library and reserve the place for other components to be added later.

I guess I applied those changes now? I'm not sure, I have never seen target names with double colons before. I can't find any documentation on how to use namespacing and components properly, but I can build glacier-music with CMake and linking to Glacier::App now.

I'm not entirely sure when to set the target_link_libraries() with PRIVATE, PUBLIC, or INTERFACE. I've set it to PUBLIC for now, but how exactly do I know when it needs to be PRIVATE or INTERFACE?

[Kaffeine]

I didn't test it but it looks good to me.
+1

[neochapay]

OBS Build fail

[   38s] + cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_INSTALL_LIBDIR=lib -DCMAKE_VERBOSE_MAKEFILE=ON .
[   38s] -- The C compiler identification is GNU 8.3.0
[   38s] -- The CXX compiler identification is GNU 8.3.0
[   38s] -- Check for working C compiler: /usr/bin/cc
[   38s] -- Check for working C compiler: /usr/bin/cc -- works
[   38s] -- Detecting C compiler ABI info
[   38s] -- Detecting C compiler ABI info - done
[   38s] -- Detecting C compile features
[   39s] -- Detecting C compile features - done
[   39s] -- Check for working CXX compiler: /usr/bin/c++
[   39s] -- Check for working CXX compiler: /usr/bin/c++ -- works
[   39s] -- Detecting CXX compiler ABI info
[   39s] -- Detecting CXX compiler ABI info - done
[   39s] -- Detecting CXX compile features
[   40s] -- Detecting CXX compile features - done
[   40s] -- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.2") 
[   40s] CMake Error at /usr/lib/cmake/Qt5Qml/Qt5QmlConfig.cmake:27 (message):
[   40s]   The imported target "Qt5::Qml" references the file
[   40s] 
[   40s]      "/usr/lib/qt5/plugins/qmltooling/libqmldbg_messages.so"
[   40s] 
[   40s]   but this file does not exist.  Possible reasons include:
[   40s] 
[   40s]   * The file was deleted, renamed, or moved to another location.
[   40s] 
[   40s]   * An install or uninstall procedure did not complete successfully.
[   40s] 
[   40s]   * The installation package was faulty and contained
[   40s] 
[   40s]      "/usr/lib/cmake/Qt5Qml/Qt5Qml_QDebugMessageServiceFactory.cmake"
[   40s] 
[   40s]   but not all the files it references.
[   40s] 
[   40s] Call Stack (most recent call first):
[   40s]   /usr/lib/cmake/Qt5Qml/Qt5QmlConfig.cmake:173 (_qt5_Qml_check_file_exists)
[   40s]   /usr/lib/cmake/Qt5Qml/Qt5Qml_QDebugMessageServiceFactory.cmake:4 (_populate_Qml_plugin_properties)
[   40s]   /usr/lib/cmake/Qt5Qml/Qt5QmlConfigExtras.cmake:4 (include)
[   40s]   /usr/lib/cmake/Qt5Qml/Qt5QmlConfig.cmake:186 (include)
[   40s]   /usr/lib/cmake/Qt5/Qt5Config.cmake:28 (find_package)
[   40s]   CMakeLists.txt:18 (find_package)
[   40s] 
[   40s] 
[   40s] -- Configuring incomplete, errors occurred!
[   40s] See also "/home/abuild/rpmbuild/BUILD/libglacierapp-0.4.0+cmake.20200408150413.2.g82dbc4a/CMakeFiles/CMakeOutput.log".
[   40s] error: Bad exit status from /var/tmp/rpm-tmp.vLgH6B (%build)
[   40s] 
[   40s] 
[   40s] RPM build errors:
[   40s]     Bad exit status from /var/tmp/rpm-tmp.vLgH6B (%build)
[   43s] [   35.706627] SysRq : Power Off
[   43s] [   35.710170] reboot: Power down

[PureTryOut]

Interesting. That file is provided by Qt5Declarative, which I would assume pkgconfig(Qt5Qml) would install. Do we have to explicitely depend on Qt5Declarative?

[Kaffeine]

CMake Find Module (namely Qt5QmlConfig.cmake) creates targets which reference to all available plugins. Later on CMake validates the targets and fails because the referenced files not found.
Qt5QmlConfig.cmake marked QDebugMessageServiceFactory as available because it found its CMake devel file /usr/lib/cmake/Qt5Qml/Qt5Qml_QDebugMessageServiceFactory.cmake. The package that containing this Qt5Qml_QDebugMessageServiceFactory.cmake devel file must requires the package that provides /usr/lib/qt5/plugins/qmltooling/libqmldbg_messages.so (and maybe some more files).

It is an issue in Mer packaging that devel rpm doesn't require its non-devel counterpart.