CMake how to install shared STL libraries for Android?

According to the Android NDK documentation (https://android.googlesource.com/platform/ndk/+/master/docs/BuildSystemMaintainers.md#STL).

"If using the shared variant, libc++_shared.so must be included in the APK."

Therefore as part of my CMake installation I'd like to install libc++_shared.so during my CMake installation if CMAKE_ANDROID_STL_TYPE is equal to c++_shared.

I tried using install(RUNTIME_DEPENDENCY_SET but it doesn't seem to work with Android builds. As of CMake 3.27.

> Note that file(GET_RUNTIME_DEPENDENCIES) only supports collecting the runtime dependencies for Windows, Linux and macOS platforms, so install(RUNTIME_DEPENDENCY_SET) has the same limitation.

I have a workaround involving a python script to find the appropriate libc++_shared.so for the ABI I'm compiling against. But I'm hoping for a more elegant solution to the problem.

Here is the solution I came up with:

NOTES:

• abis.json is parsed to get the triple since the CMake Android toolchain doesn't provide it. This approach is robust enough to handle future ABI(s).
• Requires at least CMake 3.19 due to string(JSON usage
• CMAKE_SYSROOT is set by the android toolchain to the appropriate location

Supporting documetnation:

• https://android.googlesource.com/platform/ndk/+/master/docs/BuildSystemMaintainers.md#architectures
  • abis.json lets us get query the triple based on CMAKE_ANDROID_ARCH_ABI
• https://android.googlesource.com/platform/ndk/+/master/docs/BuildSystemMaintainers.md#STL
  • "This library is installed to <NDK>/sysroot/usr/lib/<triple>."

if ("${CMAKE_ANDROID_STL_TYPE}" MATCHES "shared")
    file(READ "${CMAKE_ANDROID_NDK}/meta/abis.json" JSON_FILE)
    string(JSON TRIPLE GET "${JSON_FILE}" "${CMAKE_ANDROID_ARCH_ABI}" "triple")
    install(FILES "${CMAKE_SYSROOT}/usr/lib/${TRIPLE}/libc++_shared.so" DESTINATION "${CMAKE_INSTALL_LIBDIR}")
endif()

EDIT:

It seems like the current idiomatic answer is to use the Android Gradle Plugin to handle this for you.

Link to relevant conversation with an Android NDK developer: https://github.com/android/ndk/issues/1905

So the above code is only useful if you don't want to use the Android Gradle Plugin.