Protobuffer cross-compiling for Android

[Nour El Menshawy]

Hello 

I'm facing an issue that consumes a lot of time trying to find out what is the issue and i hope someone could help 

I build Protobuffer for windows by using the following CMake and it does work 

some of the setting flags are duplicated but it's okay 

# === definitions ===

include(FetchContent)

set(CMAKE_POSITION_INDEPENDENT_CODE ON)

set(BUILD_TESTING OFF)

set(protobuf_MSVC_STATIC_RUNTIME OFF)

set(protobuf_USE_EXTERNAL_GTEST ON)

SET(protobuf_BUILD_SHARED_LIBS OFF CACHE BOOL "Build Shared Libraries" FORCE)

SET(protobuf_MSVC_STATIC_RUNTIME OFF CACHE BOOL "Link static runtime libraries" FORCE)

message(CHECK_START "Fetching Protobuf")

list(APPEND CMAKE_MESSAGE_INDENT "  ")

FetchContent_Declare(

  protobuf

  GIT_REPOSITORY "https://github.com/protocolbuffers/protobuf.git"

  GIT_TAG "v21.12"

  FIND_PACKAGE_ARGS NAMES protobuf

  )

set(protobuf_BUILD_TESTS OFF CACHE INTERNAL "")

FetchContent_MakeAvailable(protobuf)

list(POP_BACK CMAKE_MESSAGE_INDENT)

message(CHECK_PASS "fetched")

include(Findprotobuf)

include_directories(${Protobuf_INCLUDE_DIRS})

include_directories(${CMAKE_CURRENT_BINARY_DIR})

# === targets ===

protobuf_generate_cpp(PROTO_SRC PROTO_HEADER media.proto)

message("PROTO_SRC ${PROTO_SRC}")

message("PROTO_HEADER ${PROTO_HEADER}")

add_library(PROTO STATIC  ${PROTO_HEADER} ${PROTO_SRC} CProtoWrapper.cpp)

target_link_libraries(PROTO

    PUBLIC

        protobuf::libprotobuf

        ${protobuf_LIBRARIES}

       

)

target_include_directories(PROTO PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>)

#=== install ===

install(TARGETS PROTO EXPORT PROTO_Targets

        RUNTIME COMPONENT PROTO_Runtime

        LIBRARY COMPONENT PROTO_Runtime

        NAMELINK_COMPONENT PROTO_Development

        ARCHIVE COMPONENT PROTO_Development

        INCLUDES DESTINATION "${CMAKE_INSTALL_LIBDIR}")

install(EXPORT PROTO_Targets

        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/PROTO

        COMPONENT PROTO_Development)  

Now using the same file but crossing-compiling for android and invoking CMake using the following  python script 

    cmake_args += [

        f"-D CMAKE_TOOLCHAIN_FILE={ndk_dir}\\build\\cmake\\android.toolchain.cmake",

        f"-D CMAKE_MAKE_PROGRAM={sdk_dir}\\cmake\\3.18.1\\bin\\ninja.exe",

        f"-D ANDROID_PLATFORM=android-21",

        f"-D CMAKE_EXPORT_COMPILE_COMMANDS=ON",

        f"-D CMAKE_VERBOSE_MAKEFILE=ON",

       f"-D ANDROID_ABI=x86_64",

       f"-D SWYPE_APK_BUILD_ABI=i86_android_64bit"

        f"-D CMAKE_IMPORT_LIBRARY_SUFFIX=.a"

    ]

    subprocess.run(

        ["cmake", "-G Ninja Multi-Config","-S", ".."] + cmake_args, check=True

    )

 

now ninja compiler uses this line which causes an issue in building 

protobuf::protoc --cpp_out, where protobuf::protoc has no expansion in that case 

Any idea would be appreciated 

Thanks