Cannot build with Plasma 6 (even with recommended cmake option -DQT_MAJOR_VERSION=6)

[Static-1248]

Describe the bug

As usual I checked the update and build and failed again. But this time it comes with ... something more complicated.
Seems -DQT_MAJOR_VERSION=6 won't work properly.

System Information

• Kde: 6.0.0
• Qt: not very sure

    $ qmake --version
    QMake version 3.1
    Using Qt version 5.15.12 in /usr/lib/x86_64-linux-gnu
  
  $ qmake6 --version
  QMake version 3.1
  Using Qt version 6.6.3 in /usr/lib/x86_64-linux-gnu

• OS: KDE Neon
• Installation Source: git
• Wallpaper Engine version:

Additional context

well I ran

$ sudo apt install build-essential libvulkan-dev plasma-workspace-dev gstreamer1.0-libav liblz4-dev libmpv-dev python3-websockets qtbase5-private-dev libqt5x11extras5-dev qml-module-qtwebchannel qml-module-qtwebsockets cmake
// Turns out all the newest
$ git pull //Since I've once built successfully and been using it before Plasma6 Update
$ git submodule update --init
$ rm -r build
$ mkdir build
$ cd build

and I follow the recommendation in #344 , adding the -DQT_MAJOR_VERSION=6 cmake option:

$ cmake .. -DQT_MAJOR_VERSION=6 -DUSE_PLASMAPKG=OFF

-- The C compiler identification is GNU 11.4.0
-- The CXX compiler identification is GNU 11.4.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Setting build type to 'RelWithDebInfo' as none was specified.
***Unknown option --query
CMake Warning at /usr/share/ECM/modules/ECMQueryQt.cmake:97 (message):
  Failed call: /usr/lib/x86_64-linux-gnu/qt5/bin/qmake --query
  QT_INSTALL_PREFIX
Call Stack (most recent call first):
  /usr/share/ECM/kde-modules/KDEInstallDirs6.cmake:199 (ecm_query_qt)
  /usr/share/ECM/kde-modules/KDEInstallDirs.cmake:15 (include)
  CMakeLists.txt:30 (include)


CMake Error at /usr/share/ECM/modules/ECMQueryQt.cmake:98 (message):
  Qt6 qtpaths call failed: 1
Call Stack (most recent call first):
  /usr/share/ECM/kde-modules/KDEInstallDirs6.cmake:199 (ecm_query_qt)
  /usr/share/ECM/kde-modules/KDEInstallDirs.cmake:15 (include)
  CMakeLists.txt:30 (include)


-- Configuring incomplete, errors occurred!

And I found in /usr/share/ECM/modules/ECMQueryQt.cmake: Line 47-69

if (QT_MAJOR_VERSION STREQUAL "5")
    # QUIET to accommodate the TRY option
    find_package(Qt${QT_MAJOR_VERSION}Core QUIET)
    if(TARGET Qt5::qmake)
        get_target_property(_qmake_executable_default Qt5::qmake LOCATION)

        set(QUERY_EXECUTABLE ${_qmake_executable_default}
            CACHE FILEPATH "Location of the Qt5 qmake executable")
        set(_exec_name_text "Qt5 qmake")
        set(_cli_option "-query")
    endif()
elseif(QT_MAJOR_VERSION STREQUAL "6")
    # QUIET to accommodate the TRY option
    find_package(Qt6 COMPONENTS CoreTools QUIET CONFIG)
    if (TARGET Qt6::qtpaths)
        get_target_property(_qtpaths_executable Qt6::qtpaths LOCATION)

        set(QUERY_EXECUTABLE ${_qtpaths_executable}
            CACHE FILEPATH "Location of the Qt6 qtpaths executable")
        set(_exec_name_text "Qt6 qtpaths")
        set(_cli_option "--query")
    endif()
endif()

After referencing kde invent - ECM:
They think by default qtpath is used rather by qmake by default, and qtpath accepts both "-query" & "--query" option, while qmake only accepts "-query" option.

To log out the variables in this code block, adding a message after line 65:

    if (TARGET Qt6::qtpaths)
        get_target_property(_qtpaths_executable Qt6::qtpaths LOCATION)

        set(QUERY_EXECUTABLE ${_qtpaths_executable}
            CACHE FILEPATH "Location of the Qt6 qtpaths executable")
        message(WARNING "*********************************QUERY_EXECUTABLE=${QUERY_EXECUTABLE}    _qtpaths_executable=${_qtpaths_executable}")
        set(_exec_name_text "Qt6 qtpaths")
        set(_cli_option "--query")
    endif()

$ cmake .. -DQT_MAJOR_VERSION=6 -DUSE_PLASMAPKG=OFF
CMake Warning at /usr/share/ECM/modules/ECMQueryQt.cmake:66 (message):
  
  *********************************QUERY_EXECUTABLE=/usr/lib/x86_64-linux-gnu/qt5/bin/qmake
  _qtpaths_executable=/usr/lib/qt6/bin/qtpaths
Call Stack (most recent call first):
  /usr/share/ECM/kde-modules/KDEInstallDirs6.cmake:198 (include)
  /usr/share/ECM/kde-modules/KDEInstallDirs.cmake:15 (include)
  CMakeLists.txt:30 (include)


***Unknown option --query
CMake Warning at /usr/share/ECM/modules/ECMQueryQt.cmake:98 (message):
  Failed call: /usr/lib/x86_64-linux-gnu/qt5/bin/qmake --query
  QT_INSTALL_PREFIX
Call Stack (most recent call first):
  /usr/share/ECM/kde-modules/KDEInstallDirs6.cmake:199 (ecm_query_qt)
  /usr/share/ECM/kde-modules/KDEInstallDirs.cmake:15 (include)
  CMakeLists.txt:30 (include)


CMake Error at /usr/share/ECM/modules/ECMQueryQt.cmake:99 (message):
  Qt6 qtpaths call failed: 1
Call Stack (most recent call first):
  /usr/share/ECM/kde-modules/KDEInstallDirs6.cmake:199 (ecm_query_qt)
  /usr/share/ECM/kde-modules/KDEInstallDirs.cmake:15 (include)
  CMakeLists.txt:30 (include)


-- Configuring incomplete, errors occurred!

Adding FORCE option to line 64 to let it overwrite that cache variable with its old "qmake" value:

        get_target_property(_qtpaths_executable Qt6::qtpaths LOCATION)

        set(QUERY_EXECUTABLE ${_qtpaths_executable}
            CACHE FILEPATH "Location of the Qt6 qtpaths executable" FORCE)
        set(_exec_name_text "Qt6 qtpaths")
        set(_cli_option "--query")

$ cmake .. -DQT_MAJOR_VERSION=6 -DUSE_PLASMAPKG=OFF
-- Installing in the same prefix as Qt, adopting their path scheme.
CMake Warning (dev) at /usr/lib/x86_64-linux-gnu/cmake/KF5Package/KF5PackageQchTargets.cmake:6 (set_target_properties):
  Policy CMP0160 is not set: More read-only target properties now error when
  trying to set them.  Run "cmake --help-policy CMP0160" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  IMPORTED property is read-only for target("KF5Package_QCH")

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/KF5Package/KF5PackageConfig.cmake:47 (include)
  /usr/share/ECM/find-modules/FindKF5.cmake:52 (find_package)
  CMakeLists.txt:31 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at /usr/lib/x86_64-linux-gnu/cmake/KF5CoreAddons/KF5CoreAddonsQchTargets.cmake:6 (set_target_properties):
  Policy CMP0160 is not set: More read-only target properties now error when
  trying to set them.  Run "cmake --help-policy CMP0160" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  IMPORTED property is read-only for target("KF5CoreAddons_QCH")

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/KF5CoreAddons/KF5CoreAddonsConfig.cmake:115 (include)
  /usr/share/cmake-3.29/Modules/CMakeFindDependencyMacro.cmake:76 (find_package)
  /usr/lib/x86_64-linux-gnu/cmake/KF5Package/KF5PackageConfig.cmake:55 (find_dependency)
  /usr/share/ECM/find-modules/FindKF5.cmake:52 (find_package)
  CMakeLists.txt:31 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Found KF5Package: /usr/lib/x86_64-linux-gnu/cmake/KF5Package/KF5PackageConfig.cmake (found version "5.115.0")
-- Could NOT find KF5Plasma (missing: KF5Plasma_DIR)
-- Could NOT find KF5Plasma: found neither KF5PlasmaConfig.cmake nor kf5plasma-config.cmake 
-- KF5_FOUND="" ; KF5_VERSION="5.115.0"
CMake Error at /usr/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find KF5 (missing: Plasma) (found suitable version "5.115.0",
  minimum required is "5.68.0")
Call Stack (most recent call first):
  /usr/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/ECM/find-modules/FindKF5.cmake:96 (find_package_handle_standard_args)
  CMakeLists.txt:31 (find_package)


-- Configuring incomplete, errors occurred!

Fallback to what's reported in this comment.

Also, after removing "FORCE" option and left that cmake file remains originally, executing the cmake command will print the same last error message, not complaining the "--query" option anymore.

---

So far I am not sure which side should this problem belong to, the qt6 ,the ECM cmake script, or the recommendation in #344 .

Maybe it indicates a comprehensive irrational design in our multi-party building system.

I'll also report this problem on ECM's repo, and also hope anyone could help me with the original problem in this comment.

Thanks for you all!

[Static-1248]

Oh btw the error in this comment doesn't occur after switching to branch "qt6" and fixing the qt installation query using the same steps as above, but the building still can't be completed successfully:

$ cmake .. -DQT_MAJOR_VERSION=6 -DUSE_PLASMAPKG=OFF
CMake Warning (dev) at /usr/lib/x86_64-linux-gnu/cmake/Plasma/PlasmaQchTargets.cmake:6 (set_target_properties):
  Policy CMP0160 is not set: More read-only target properties now error when
  trying to set them.  Run "cmake --help-policy CMP0160" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  IMPORTED property is read-only for target("Plasma_QCH")

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/Plasma/PlasmaConfig.cmake:40 (include)
  CMakeLists.txt:43 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at /usr/lib/x86_64-linux-gnu/cmake/KF6Package/KF6PackageQchTargets.cmake:6 (set_target_properties):
  Policy CMP0160 is not set: More read-only target properties now error when
  trying to set them.  Run "cmake --help-policy CMP0160" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  IMPORTED property is read-only for target("KF6Package_QCH")

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/KF6Package/KF6PackageConfig.cmake:47 (include)
  /usr/share/cmake-3.29/Modules/CMakeFindDependencyMacro.cmake:76 (find_package)
  /usr/lib/x86_64-linux-gnu/cmake/Plasma/PlasmaConfig.cmake:52 (find_dependency)
  CMakeLists.txt:43 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at /usr/lib/x86_64-linux-gnu/cmake/KF6CoreAddons/KF6CoreAddonsQchTargets.cmake:6 (set_target_properties):
  Policy CMP0160 is not set: More read-only target properties now error when
  trying to set them.  Run "cmake --help-policy CMP0160" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  IMPORTED property is read-only for target("KF6CoreAddons_QCH")

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/KF6CoreAddons/KF6CoreAddonsConfig.cmake:97 (include)
  /usr/share/cmake-3.29/Modules/CMakeFindDependencyMacro.cmake:76 (find_package)
  /usr/lib/x86_64-linux-gnu/cmake/KF6Package/KF6PackageConfig.cmake:55 (find_dependency)
  /usr/share/cmake-3.29/Modules/CMakeFindDependencyMacro.cmake:76 (find_package)
  /usr/lib/x86_64-linux-gnu/cmake/Plasma/PlasmaConfig.cmake:52 (find_dependency)
  CMakeLists.txt:43 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Found X11: /usr/include
-- Looking for XOpenDisplay in /usr/lib/x86_64-linux-gnu/libX11.so;/usr/lib/x86_64-linux-gnu/libXext.so
-- Looking for XOpenDisplay in /usr/lib/x86_64-linux-gnu/libX11.so;/usr/lib/x86_64-linux-gnu/libXext.so - found
-- Looking for gethostbyname
-- Looking for gethostbyname - found
-- Looking for connect
-- Looking for connect - found
-- Looking for remove
-- Looking for remove - found
-- Looking for shmat
-- Looking for shmat - found
-- Looking for IceConnectionNumber in ICE
-- Looking for IceConnectionNumber in ICE - found
CMake Warning (dev) at /usr/lib/x86_64-linux-gnu/cmake/KF6WindowSystem/KF6WindowSystemQchTargets.cmake:6 (set_target_properties):
  Policy CMP0160 is not set: More read-only target properties now error when
  trying to set them.  Run "cmake --help-policy CMP0160" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  IMPORTED property is read-only for target("KF6WindowSystem_QCH")

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/KF6WindowSystem/KF6WindowSystemConfig.cmake:51 (include)
  /usr/share/cmake-3.29/Modules/CMakeFindDependencyMacro.cmake:76 (find_package)
  /usr/lib/x86_64-linux-gnu/cmake/Plasma/PlasmaConfig.cmake:53 (find_dependency)
  CMakeLists.txt:43 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Found KF6Package: /usr/lib/x86_64-linux-gnu/cmake/KF6Package/KF6PackageConfig.cmake (found version "6.0.0")
-- Found KF6: success (found suitable version "6.0.0", minimum required is "5.68.0") found components: Package
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.2")
-- Checking for module 'mpv'
--   Found mpv, version 1.109.0
CMake Error at src/CMakeLists.txt:6 (add_subdirectory):
  The source directory

    /mnt/linux_data/codings/Neon/wallpaper-engine-kde-plugin/src/backend_scene

  does not contain a CMakeLists.txt file.


-- Configuring incomplete, errors occurred!

I guess the "qt6" branch has fixed my original KF5 problem in that comment, using KF6 properly(?), but due to unknown reason the source files under /src/backend_scene are incomplete.

On branch "main" the source files under /src/backend_scene seems surely complete, but it hasn't merged the bugfix I needed in branch "qt6".