Android NDK制作。数百 "undefined reference error" 秒

Question

在尝试构建此示例项目时 https://github.com/caffe2/AICamera/tree/master/app/src/main/cpp 我得到了数百个 error: undefined reference。这是前几行输出：

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:externalNativeBuildDebug'.
> Build command failed.
  Error while executing process /home/aidan/Android/Sdk/cmake/3.6.4111459/bin/cmake with arguments {--build /home/aidan/AndroidStudioProjects/AICamera/app/.externalNativeBuild/cmake/debug/armeabi-v7a --target native-lib}
  [1/1] Linking CXX shared library ../../../../build/intermediates/cmake/debug/obj/armeabi-v7a/libnative-lib.so
  FAILED: : && /home/aidan/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++  --target=armv7-none-linux-androideabi --gcc-toolchain=/home/aidan/Android/Sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 --sysroot=/home/aidan/Android/Sdk/ndk-bundle/sysroot -fPIC -isystem /home/aidan/Android/Sdk/ndk-bundle/sysroot/usr/include/arm-linux-androideabi -D__ANDROID_API__=22 -g -DANDROID -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mthumb -Wa,--noexecstack -Wformat -Werror=format-security -std=c++11 -frtti -fexceptions -std=c++11 -O0 -fno-limit-debug-info  -Wl,--exclude-libs,libgcc.a -Wl,--exclude-libs,libatomic.a -nostdlib++ --sysroot /home/aidan/Android/Sdk/ndk-bundle/platforms/android-22/arch-arm -Wl,--build-id -Wl,--warn-shared-textrel -Wl,--fatal-warnings -Wl,--fix-cortex-a8 -Wl,--exclude-libs,libunwind.a -L/home/aidan/Android/Sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a -Wl,--no-undefined -Wl,-z,noexecstack -Qunused-arguments -Wl,-z,relro -Wl,-z,now -shared -Wl,-soname,libnative-lib.so -o ../../../../build/intermediates/cmake/debug/obj/armeabi-v7a/libnative-lib.so CMakeFiles/native-lib.dir/src/main/cpp/native-lib.cpp.o  -Wl,--whole-archive ../../../../src/main/jniLibs/armeabi-v7a/libCaffe2_CPU.a -Wl,--no-whole-archive ../../../../src/main/jniLibs/armeabi-v7a/libCAFFE2_NNPACK.a ../../../../src/main/jniLibs/armeabi-v7a/libCAFFE2_PTHREADPOOL.a ../../../../src/main/jniLibs/armeabi-v7a/libglog.so ../../../../src/main/jniLibs/armeabi-v7a/libprotobuf.a libcpufeatures.a /home/aidan/Android/Sdk/ndk-bundle/platforms/android-22/arch-arm/usr/lib/liblog.so /home/aidan/Android/Sdk/ndk-bundle/platforms/android-22/arch-arm/usr/lib/libandroid.so -ldl -latomic -lm "/home/aidan/Android/Sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++_static.a" "/home/aidan/Android/Sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libc++abi.a" "/home/aidan/Android/Sdk/ndk-bundle/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a/libunwind.a" "-ldl" && :
  ../../../../src/main/jniLibs/armeabi-v7a/libCaffe2_CPU.a(nnpack_ops.cc.o):nnpack_ops.cc:function std::_Sp_counted_deleter<void*, void (*)(void*), std::allocator<void>, (__gnu_cxx::_Lock_policy)2>::_M_get_deleter(std::type_info const&): error: undefined reference to 'std::type_info::operator==(std::type_info const&) const'
  ../../../../src/main/jniLibs/armeabi-v7a/libCaffe2_CPU.a(nnpack_ops.cc.o):nnpack_ops.cc:function std::_Sp_counted_deleter<void*, caffe2::Tensor<caffe2::CPUContext>::raw_mutable_data(caffe2::TypeMeta const&)::{lambda(void*)#1}, std::allocator<void>, (__gnu_cxx::_Lock_policy)2>::_M_get_deleter(std::type_info const&): error: undefined reference to 'std::type_info::operator==(std::type_info const&) const'
  ../../../../src/main/jniLibs/armeabi-v7a/libCaffe2_CPU.a(nnpack_ops.cc.o):nnpack_ops.cc:function void caffe2::TypeMeta::_CopyNotAllowed<caffe2::Tensor<caffe2::CPUContext> >(void const*, void*, unsigned int): error: undefined reference to 'std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, int)'
... + 100s of similar lines, all with undefined references

这是我第一次尝试 Android NDK，所以我是新手，在构建 C++ 方面经验有限。据我所知，这似乎是一个链接错误，因为它似乎无法找到 std。由于我的经验有限，我不知道如何解决这个问题。

这是我的 CMakeLists.txt 文件

cmake_minimum_required(VERSION 3.4.1)

add_library(
             native-lib
             SHARED
             src/main/cpp/native-lib.cpp
             )
find_library(
          android-lib
          android
          )

include(AndroidNdkModules)
android_ndk_import_module_cpufeatures()

add_library(
    caffe2
    STATIC
    IMPORTED
    )
set_target_properties(
    caffe2
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_CURRENT_LIST_DIR}/src/main/jniLibs/${ANDROID_ABI}/libCaffe2_CPU.a
    )
add_library(
    thread_pool
    STATIC
    IMPORTED
    )
set_target_properties(
    thread_pool
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_CURRENT_LIST_DIR}/src/main/jniLibs/${ANDROID_ABI}/libCAFFE2_PTHREADPOOL.a
    )
add_library(
    glog
    SHARED
    IMPORTED
    )
set_target_properties(
    glog
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_CURRENT_LIST_DIR}/src/main/jniLibs/${ANDROID_ABI}/libglog.so
    )

add_library(
    protobuf
    SHARED
    IMPORTED
    )
set_target_properties(
    protobuf
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_CURRENT_LIST_DIR}/src/main/jniLibs/${ANDROID_ABI}/libprotobuf.a
    )

add_library(
    NNPACK
    STATIC
    IMPORTED
    )
set_target_properties(
    NNPACK
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_CURRENT_LIST_DIR}/src/main/jniLibs/${ANDROID_ABI}/libCAFFE2_NNPACK.a
    )

include_directories( src/main/cpp )

find_library(
     log-lib
     log
     )

target_link_libraries(
                       native-lib
                       -Wl,--whole-archive
                       caffe2
                       -Wl,--no-whole-archive
                       NNPACK
                       thread_pool
                       glog
                       protobuf
                       cpufeatures
                       ${log-lib}
                       ${android-lib})

Answer 1

caffe2/AICamera 本机库是为 libgnustl_shared.so 预构建的（参见 jniLibs），但是您的项目使用 libc++_static.a 代替。你应该指定

externalNativeBuild {
    cmake {
        arguments "-DANDROID_STL=gnustl_shared"
    }
}

在您的 build.gradle 中，或重建 libCaffe2_ 库。

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