Command line Android builds

[GoodOldGamer]

• I've read Brief overview section and do understand basic concepts. [Yes]
• I've read F.A.Q. section and haven't found an answer to my question. [Yes]
• I've read Code of Conduct, I promise to be polite and will do my best at being constructive. [Yes]

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I'm trying to build the library mtxclient from the nheko project for Android. They offer the option to download & build dependencies like OpenSSL, libcurl etc. via Hunter, which works fine for Linux, but fails for Android-

In my first try, cmake was defaulting to arm with API level 16 because ANDROID_PLATFORM was not set. This resulted of course in an ABI mismatch when the dependencies were linked against the mtxclient lib. So I forwarded the CMAKE_ARGS in hunter_config:

hunter_config(
      OpenSSL
      VERSION 1.1.1j
      CMAKE_ARGS 
        ANDROID_ABI=${ANDROID_ABI} 
        ANDROID_PLATFORM=${ANDROID_PLATFORM}
        ANDROID_NDK=${ANDROID_NDK}
        ANDROID_SDK=${ANDROID_SDK}
        ANDROID_STL=${ANDROID_STL}
)

But this lead to a linker error while linking the dependency against system libs:
ld: error: unable to find library -l-l:libunwind.a

I'm using the following environment and cmake call to build the lib:

export ANDROID_ABI=x86
export ANDROID_API_LEVEL=21
export ANDROID_PLATFORM=android-${ANDROID_API_LEVEL}
export ANDROID_SDK_DIR=${HOME}/apps/Android/SDK
export ANDROID_NDK_DIR=${HOME}/apps/Android/SDK/ndk/23.1.7779620

mkdir -p build/android/${ANDROID_ABI}
cd build/android/${ANDROID_ABI}

cmake \
    -DANDROID_ABI:STRING=${ANDROID_ABI} \
    -DANDROID_PLATFORM=${ANDROID_PLATFORM} \
    -DANDROID_NDK:PATH=${ANDROID_NDK_DIR} \
    -DANDROID_SDK:PATH=${ANDROID_SDK_DIR} \
    -DANDROID_STL:STRING=c++_shared \
    -DCMAKE_BUILD_TYPE:STRING=Release \
    -DCMAKE_CXX_COMPILER:STRING=${ANDROID_NDK_DIR}/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ \
    -DCMAKE_C_COMPILER:STRING=${ANDROID_NDK_DIR}/toolchains/llvm/prebuilt/linux-x86_64/bin/clang \
    -DCMAKE_TOOLCHAIN_FILE:PATH=${ANDROID_NDK_DIR}/build/cmake/android.toolchain.cmake \
    -DCMAKE_INSTALL_PREFIX=${HOME}/development/build/mtxclient/${ANDROID_ABI} \
    -DHUNTER_ENABLED=ON \
    -DUSE_BUNDLED_COEURL=yes \
    -DUSE_BUNDLED_LIBEVENT=yes \
    -DUSE_BUNDLED_LIBCURL=yes \
    -DUSE_BUNDLED_SPDLOG=yes \
    -DUSE_BUNDLED_OLM=yes \
    -DUSE_BUNDLED_GTEST=yes \
    -DUSE_BUNDLED_JSON=yes \
    -DUSE_BUNDLED_OPENSSL=yes \
    ../../..

What's the right way of passing ABI and API level to Hunter dependencies when building for Android?
Is it still up to date that NDK version 19+ is not supported by built-in CMake modules?

[rbsheth]

Hi @GoodOldGamer, typically we use polly toolchains to build for Android/iOS. Your CMake command would look more like cmake -DCMAKE_TOOLCHAIN_FILE=<selected android toolchain from polly>.cmake ... and it should work. The Android toolchains haven't been updated in a while, so feel free to update with a new PR if you'd like!

Example toolchain file: https://github.com/cpp-pm/polly/blob/master/android-ndk-r18b-api-28-arm64-v8a-clang-libcxx11.cmake

[GoodOldGamer]

Ok, I removed the variable forwarding from hunter_config and used an upgraded polly toolchain to build, but OpenSSL still fails with ld: error: unable to find library -l-l:libunwind.a.

That's my toolchain file:

if(DEFINED POLLY_ANDROID_NDK_R23_API_21_X86_CMAKE_)
  return()
else()
  set(POLLY_ANDROID_NDK_R23_API_21_X86_CMAKE_ 1)
endif()

include("${CMAKE_CURRENT_LIST_DIR}/utilities/polly_clear_environment_variables.cmake")

include("${CMAKE_CURRENT_LIST_DIR}/utilities/polly_init.cmake")

set(ANDROID_NDK_VERSION "r23")
set(CMAKE_SYSTEM_VERSION "21")
set(CMAKE_ANDROID_ARCH_ABI "x86")
set(CMAKE_ANDROID_NDK_TOOLCHAIN_VERSION "clang")
set(CMAKE_ANDROID_STL_TYPE "c++_static") # LLVM libc++ static

polly_init(
    "Android NDK ${ANDROID_NDK_VERSION} / \
API ${CMAKE_SYSTEM_VERSION} / ${CMAKE_ANDROID_ARCH_ABI} / \
Clang / c++11 support / libc++ static"
    "Unix Makefiles"
)

include("${CMAKE_CURRENT_LIST_DIR}/utilities/polly_common.cmake")

include("${CMAKE_CURRENT_LIST_DIR}/flags/cxx11.cmake") # before toolchain!

include("${CMAKE_CURRENT_LIST_DIR}/os/android.cmake")

Any ideas? Can't see any necessary changes in the included files.

[NeroBurner]

since #780 we now generate the toolchains for the CI on the fly using set_matrix.py

Open for PRs to improve the currently generated toolchains. Please reopen or open new issue if this is still a problem