SO Files not getting generated in Android Studio with CMake

Question

We were using Android.mk & Application.mk NDK builds system. As we have common modules in the native layer which are being used by multiple projects, as the other projects are already supporting CMakeLists.txt , we are moving our Android project as well to CMake.

I have multiple static libraries in the sub-directories and the main directory ( jni/ ) is generating the SO file. I have written CMakeLists.txt individually in the sub-directories and included them (add_subdirectory) in the jni/CmakeLists.txt file.
I see compilation is going through but not able to find the .so files either in build/intermediates/cmake/release/obj/armeabi or project/libs folder. But I see the below message int he Android Studio Gralde

Excerpt from the below:

-soname,liblogger.so -o /home/suman//build/intermediates/cmake/release/obj/armeabi-v7a/liblogger.so Logger/CMakeFiles/logger.dir/src/Logger.cpp.o

Full Command:

[2/2] : && /home/suman/Android/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ --target=armv7-none-linux-androideabi --gcc-toolchain=/home/suman/Android/android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 --sysroot=/home/suman/Android/android-ndk/sysroot -fPIC -isystem /home/suman/Android/android-ndk/sysroot/usr/include/arm-linux-androideabi -D__ANDROID_API__=21 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -fno-integrated-as -marm -Wa,--noexecstack -Wformat -Werror=format-security -frtti -fexceptions -fvisibility=hidden -fstack-protector-all -Wall -c -fmessage-length=0 -Os -DNDEBUG
-Wl,--exclude-libs,libgcc.a -Wl,--exclude-libs,libatomic.a --sysroot /home/suman/Android/android-ndk/platforms/android-21/arch-arm -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -Wl,--fix-cortex-a8 -Wl,--no-undefined -Wl,-z,noexecstack -Qunused-arguments -Wl,-z,relro -Wl,-z,now -shared -Wl,-soname,liblogger.so -o /home/suman//build/intermediates/cmake/release/obj/armeabi-v7a/liblogger.so Logger/CMakeFiles/logger.dir/src/Logger.cpp.o /home/suman/Android/android-ndk/platforms/android-21/arch-arm/usr/lib/liblog.so -latomic -lm "/home/suman/Android/android-ndk/sources/cxx-stl/gnu-libstdc++/4.9/libs/armeabi-v7a/libsupc++.a" "/home/suman/Android/android-ndk/sources/cxx-stl/gnu-libstdc++/4.9/libs/armeabi-v7a/libgnustl_shared.so" && :

Am I missing anything?

My folder structure is old Android build folder structure (Eclipse Folder Structure) - Flat structure. As project is pretty old and huge, didn't got migrated to new folder structure instead we are specifying the sourceSets in the build.gradle file.

Answer 1

1) Got the issue fixed. I was setting some CMake variables before declaring the project(), due to which those settings were taking effect only in that file. It was not propagating to the the included_directories() and add_dependencies().

2) Don't declare any externalCMakeBuild { cppFlags } in the build.gradle file. It was messing up with NDK flags set by the build system.