Linker error when building for Android

[JeroenvdV]

Not sure what to try, let me know how I can help. I cloned the repository, and am running flutter build apk -v. Then the error is:

e: /home/jeroen/.gradle/caches/modules-2/files-2.1/androidx.lifecycle/lifecycle-common/2.6.1/10f354fdb64868baecd67128560c5a0d6312c495/lifecycle-common-2.6.1.jar!/META-INF/lifecycle-common.kotlin_module: Module was
compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.8.0, expected version is 1.6.0.

To fix this, I changed ext.kotlin_version to 1.8.10 from 1.6.10.

Note, also gradle was upgraded automatically:

Upgrading build.gradle
Conflict detected between Android Studio Java version and Gradle version, upgrading Gradle version from 6.7 to 7.6.1.
Upgrading gradle-wrapper.properties

The next error is:

[        ] Execution failed for task ':app:processReleaseMainManifest'.
[        ] > Unable to make field private final java.lang.String java.io.File.path accessible: module java.base does not "opens java.io" to unnamed module @76cbb5e7

To fix, I changed android/gradle.properties to:

org.gradle.jvmargs=-Xmx1536M \
--add-exports=java.base/sun.nio.ch=ALL-UNNAMED \
--add-opens=java.base/java.lang=ALL-UNNAMED \
--add-opens=java.base/java.lang.reflect=ALL-UNNAMED \
--add-opens=java.base/java.io=ALL-UNNAMED \
--add-exports=jdk.unsupported/sun.misc=ALL-UNNAMED
android.useAndroidX=true
android.enableJetifier=true

Finally, the linker error I can't solve is:

        ] Execution failed for task ':app:externalNativeBuildRelease'.
[        ] > Build command failed.
[        ]   Error while executing process /home/jeroen/Android/Sdk/cmake/3.10.2.4988404/bin/ninja with arguments {-C /home/jeroen/Files/Ball/android/app/.cxx/cmake/release/armeabi-v7a OpenCV_ffi}
[        ]   ninja: Entering directory `/home/jeroen/Files/Ball/android/app/.cxx/cmake/release/armeabi-v7a'
[        ]   [1/2] Building CXX object CMakeFiles/OpenCV_ffi.dir/home/jeroen/Files/Ball/lib/opencv-cpp/main.cpp.o
[        ]   [2/2] Linking CXX shared library /home/jeroen/Files/Ball/build/app/intermediates/cmake/release/obj/armeabi-v7a/libOpenCV_ffi.so
[        ]   FAILED: /home/jeroen/Files/Ball/build/app/intermediates/cmake/release/obj/armeabi-v7a/libOpenCV_ffi.so 
[        ]   : && /home/jeroen/Android/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ --target=armv7-none-linux-androideabi21
--gcc-toolchain=/home/jeroen/Android/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64 --sysroot=/home/jeroen/Android/Sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/sysroot -fPIC -g -DANDROID -fdata-sections
-ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -march=armv7-a -mthumb -Wformat -Werror=format-security  -frtti -fexceptions -std=c++17 -Oz -DNDEBUG
-Wl,--exclude-libs,libgcc.a -Wl,--exclude-libs,libgcc_real.a -Wl,--exclude-libs,libatomic.a -Wl,--build-id -Wl,--fatal-warnings -Wl,--exclude-libs,libunwind.a -Wl,--no-undefined -Qunused-arguments -shared
-Wl,-soname,libOpenCV_ffi.so -o /home/jeroen/Files/Ball/build/app/intermediates/cmake/release/obj/armeabi-v7a/libOpenCV_ffi.so CMakeFiles/OpenCV_ffi.dir/home/jeroen/Files/Ball/lib/opencv-cpp/main.cpp.o
../../../../../src/main/jniLibs/armeabi-v7a/libopencv_java4.so -latomic -lm && :
[   +2 ms]   /home/jeroen/Files/Ball/lib/opencv-cpp/gaussian.cpp:6: error: undefined reference to 'cv::imread(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int)'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/gaussian.cpp:6: error: undefined reference to 'std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/gaussian.cpp:9: error: undefined reference to 'cv::imwrite(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&,
std::vector<int, std::allocator<int> > const&)'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/gaussian.cpp:9: error: undefined reference to 'std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/gaussian.cpp:9: error: undefined reference to 'std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/gaussian.cpp:6: error: undefined reference to 'std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/image_ffi.cpp:11: error: undefined reference to 'cv::putText(cv::_InputOutputArray const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >
const&, cv::Point_<int>, int, double, cv::Scalar_<double>, int, int, bool)'
[        ]   /home/jeroen/Files/Ball/lib/opencv-cpp/image_ffi.cpp:15: error: undefined reference to 'cv::imencode(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, cv::_InputArray const&,
std::vector<unsigned char, std::allocator<unsigned char> >&, std::vector<int, std::allocator<int> > const&)'
[        ]   /snap/flutter/current/usr/include/c++/9/bits/basic_string.tcc:219: error: undefined reference to 'std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_create(unsigned int&, unsigned
int)'
[        ]   /snap/flutter/current/usr/include/c++/9/bits/basic_string.tcc:212: error: undefined reference to 'std::__throw_logic_error(char const*)'
[        ]   /snap/flutter/current/usr/include/c++/9/bits/stl_vector.h:1767: error: undefined reference to 'std::__throw_length_error(char const*)'
[        ]   /snap/flutter/current/usr/include/c++/9/iostream:74: error: undefined reference to 'std::ios_base::Init::Init()'
[        ]   /snap/flutter/current/usr/include/c++/9/iostream:0: error: undefined reference to 'std::ios_base::Init::~Init()'
[        ]   clang++: error: linker command failed with exit code 1 (use -v to see invocation)
[        ]   ninja: build stopped: subcommand failed.

Does this have to do with an incompatibility between C++11 and C++17? Note how the android/app/build.gradle file specifies cppFlags '-frtti -fexceptions -std=c++17', which differs from the version on the website linked from the README.md where it specifiecs c++11. Changing this results in a different error though.