CMake error 'The CXX compiler identification is unknown' for Android developing only

glafauci61

Hi to all,
I installed QT 6.9.1 on kubuntu linux. I try to compile a demo app, exactly 'calqlatr'.
First I tried to compile as a desktop app. All OK.

Then I tried to compile for Android, choosing the x86_64 kit. As I set the kit in the 'Projects' tab, I received the following message:

So, I went to 'General messages' and I read this:

[cmake] Running /home/glafauci61/Programmi/QT6/QT/Tools/CMake/bin/cmake -S /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr -B /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr/build/Android_Qt_6_9_1_Clang_x86_64-Debug in /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr/build/Android_Qt_6_9_1_Clang_x86_64-Debug.
[cmake] -- Android: Selected unified Clang toolchain
[cmake] -- The CXX compiler identification is unknown
[cmake] -- Detecting CXX compiler ABI info
[cmake] -- Detecting CXX compiler ABI info - failed
[cmake] -- Check for working CXX compiler: /home/glafauci61/Programmi/QT6/SDK-commandLineTools/cmdline-tools/ndk/android-ndk-r28/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++
[cmake] -- Check for working CXX compiler: /home/glafauci61/Programmi/QT6/SDK-commandLineTools/cmdline-tools/ndk/android-ndk-r28/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ - broken
[cmake] CMake Error at /home/glafauci61/Programmi/QT6/QT/Tools/CMake/share/cmake-3.30/Modules/CMakeTestCXXCompiler.cmake:73 (message):
[cmake]   The C++ compiler
[cmake]
[cmake]     "/home/glafauci61/Programmi/QT6/SDK-commandLineTools/cmdline-tools/ndk/android-ndk-r28/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++"
[cmake]
[cmake]   is not able to compile a simple test program.
[cmake]
[cmake]   It fails with the following output:
[cmake]
[cmake]     Change Dir: '/home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr/build/Android_Qt_6_9_1_Clang_x86_64-Debug/CMakeFiles/CMakeScratch/TryCompile-PfFPuk'
[cmake]
[cmake]     Run Build Command(s): /home/glafauci61/Programmi/QT6/QT/Tools/Ninja/ninja -v cmTC_a24ef
[cmake]     [1/2] /home/glafauci61/Programmi/QT6/SDK-commandLineTools/cmdline-tools/ndk/android-ndk-r28/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++   -DQT_QML_DEBUG -o CMakeFiles/cmTC_a24ef.dir/testCXXCompiler.cxx.o -c /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr/build/Android_Qt_6_9_1_Clang_x86_64-Debug/CMakeFiles/CMakeScratch/TryCompile-PfFPuk/testCXXCompiler.cxx
[cmake]     FAILED: CMakeFiles/cmTC_a24ef.dir/testCXXCompiler.cxx.o
[cmake]     /home/glafauci61/Programmi/QT6/SDK-commandLineTools/cmdline-tools/ndk/android-ndk-r28/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++   -DQT_QML_DEBUG -o CMakeFiles/cmTC_a24ef.dir/testCXXCompiler.cxx.o -c /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr/build/Android_Qt_6_9_1_Clang_x86_64-Debug/CMakeFiles/CMakeScratch/TryCompile-PfFPuk/testCXXCompiler.cxx
[cmake]     /home/glafauci61/Programmi/QT6/SDK-commandLineTools/cmdline-tools/ndk/android-ndk-r28/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++: 1: clang: not found
[cmake]     ninja: build stopped: subcommand failed.
[cmake]
[cmake]
[cmake]
[cmake]
[cmake]
[cmake]   CMake will not be able to correctly generate this project.
[cmake] Call Stack (most recent call first):
[cmake]   CMakeLists.txt:5 (project)
[cmake]
[cmake]
[cmake] -- Configuring incomplete, errors occurred!
[cmake]
[cmake] The command "/home/glafauci61/Programmi/QT6/QT/Tools/CMake/bin/cmake -S /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr -B /home/glafauci61/Programmi/QT6/QT/Examples/Qt-6.9.1/demos/calqlatr/build/Android_Qt_6_9_1_Clang_x86_64-Debug" terminated with exit code 1.
[cmake]
[cmake] Elapsed time: 00:00.

Surprised, I went back to Desktop kit and retried: the compilation is OK, and the app runs perfectly.

I tried to use other android kits, but all of them fails with the same output.

Anyone can help me?

glafauci61

Hello, I solved the problem uninstalling all QT suite and reinstalling it.
Everything is fine.

Bye