C++ 链接器错误：未定义的引用 - 将包 libtorch 和共享对象链接在一起时

Question

我是 CMake 的新手，还试图了解链接的工作原理，或者是什么导致 libtorch 和 OpenNMTTokenizer.so 不能一起工作。前者是一个带有 CMake 配置的包，后者是一个共享库。

如果我删除其中任何一个，二进制文件可以正常工作，但它们不能链接到同一个项目中。可能OpenNMTTokenizer.so 缺少标题，但我不确定如何正确添加它们。

这是错误信息：

/usr/bin/ld: CMakeFiles/example_shared.dir/src/app.cpp.o: in function `main':
app.cpp:(.text+0x292): undefined reference to `onmt::Tokenizer::joiner_marker'
/usr/bin/ld: app.cpp:(.text+0x2a7): undefined reference to `onmt::Tokenizer::Tokenizer(onmt::Tokenizer::Mode, int, std::string const&, std::string const&, std::string const&, int)'
collect2: error: ld returned 1 exit status

程序是一个简单的hello world，只是为了隔离问题：

.
│
├── CMakeLists.txt
│
├── src
│   └── app.cpp
├── include
│   └── app.h.in
│   └── app.h
├── build
  

#
#. Project meta
#
cmake_minimum_required(VERSION 3.2 FATAL_ERROR)
set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_STANDARD_REQUIRED True)
project(hello_world)
configure_file(include/app.h.in include/app.h)

#
# Add libraries
#

# 1. Torch
find_package(Torch REQUIRED PATHS /usr/local/libtorch)
# Required flags 
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${TORCH_CXX_FLAGS}")
if (Torch_FOUND)
  list(APPEND LINK_LIBRARIES "${TORCH_LIBRARIES}")
else()
  message(FATAL_ERROR "Cannot find libtorch")
endif()

# 2. OpenNMTTokenizer
find_library(OpenNMTTokenizer lib/libOpenNMTTokenizer.so)
if (OpenNMTTokenizer)
  add_library(OpenNMTTokenizer SHARED IMPORTED lib/libOpenNMTTokenizer.so)
  set_target_properties(OpenNMTTokenizer
    PROPERTIES
    IMPORTED_LOCATION /usr/local/lib/libOpenNMTTokenizer.so
    LINKER_LANGUAGE CXX)
  list(APPEND LINK_LIBRARIES OpenNMTTokenizer "${OpenNMTTokenizer_LIBRARIES}")
else()
  message(FATAL_ERROR "Cannot find OpenNMTTokenizer")
endif()

#
# Add the executable
#
add_executable("${PROJECT_NAME}" src/app.cpp)
set_property(TARGET "${PROJECT_NAME}" PROPERTY CXX_STANDARD 14)
target_link_libraries("${PROJECT_NAME}" "${LINK_LIBRARIES}")

target_include_directories("${PROJECT_NAME}" PUBLIC
  "${CMAKE_SOURCE_DIR}/include"
  "${TORCH_INCLUDE_DIRS}")

set_target_properties("${PROJECT_NAME}"
  PROPERTIES
  ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/../lib"
  LIBRARY_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/../lib"
  RUNTIME_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/../bin"
)

这是来源src/app.cpp

#include "app.h"
#include <iostream>
#include <vector>
#include <torch/torch.h>
#include <torch/script.h>
#include <onmt/Tokenizer.h>

using namespace onmt;

int main(){
  torch::Tensor tensor = torch::eye(3);
  std::cout << tensor << std::endl;

  // It doesn't work if torch is linked
  Tokenizer tokenizer(Tokenizer::Mode::Conservative, Tokenizer::Flags::JoinerAnnotate);

  return 0;
}

完成构建输出

/usr/local/bin/cmake -S/home/inez/Projects/cmake_hello_world -B/home/inez/Projects/cmake_hello_world/build --check-build-system CMakeFiles/Makefile.cmake 0
/usr/local/bin/cmake -E cmake_progress_start /home/inez/Projects/cmake_hello_world/build/CMakeFiles /home/inez/Projects/cmake_hello_world/build//CMakeFiles/progress.marks
make  -f CMakeFiles/Makefile2 all
make[1]: Entering directory '/home/inez/Projects/cmake_hello_world/build'
make  -f CMakeFiles/hello_world.dir/build.make CMakeFiles/hello_world.dir/depend
make[2]: Entering directory '/home/inez/Projects/cmake_hello_world/build'
cd /home/inez/Projects/cmake_hello_world/build && /usr/local/bin/cmake -E cmake_depends "Unix Makefiles" /home/inez/Projects/cmake_hello_world /home/inez/Projects/cmake_hello_world /home/inez/Projects/cmake_hello_world/build /home/inez/Projects/cmake_hello_world/build /home/inez/Projects/cmake_hello_world/build/CMakeFiles/hello_world.dir/DependInfo.cmake --color=
Dependencies file "CMakeFiles/hello_world.dir/src/app.cpp.o.d" is newer than depends file "/home/inez/Projects/cmake_hello_world/build/CMakeFiles/hello_world.dir/compiler_depend.internal".
Consolidate compiler generated dependencies of target hello_world
make[2]: Leaving directory '/home/inez/Projects/cmake_hello_world/build'
make  -f CMakeFiles/hello_world.dir/build.make CMakeFiles/hello_world.dir/build
make[2]: Entering directory '/home/inez/Projects/cmake_hello_world/build'
[ 50%] Linking CXX executable ../bin/hello_world
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/hello_world.dir/link.txt --verbose=1
/usr/bin/c++  -D_GLIBCXX_USE_CXX11_ABI=0 -rdynamic CMakeFiles/hello_world.dir/src/app.cpp.o -o ../bin/hello_world  -Wl,-rpath,/usr/local/libtorch/lib:/usr/local/cuda-11.2/lib64/stubs:/usr/local/cuda-11.2/lib64:/usr/local/lib /usr/local/libtorch/lib/libtorch.so /usr/local/libtorch/lib/libc10.so /usr/local/libtorch/lib/libkineto.a /usr/local/cuda-11.2/lib64/stubs/libcuda.so /usr/local/cuda-11.2/lib64/libnvrtc.so -lnvToolsExt /usr/local/cuda-11.2/lib64/libcudart.so /usr/local/libtorch/lib/libc10_cuda.so /usr/local/lib/libOpenNMTTokenizer.so -Wl,--no-as-needed,"/usr/local/libtorch/lib/libtorch_cuda.so" -Wl,--as-needed -Wl,--no-as-needed,"/usr/local/libtorch/lib/libtorch_cuda_cpp.so" -Wl,--as-needed -Wl,--no-as-needed,"/usr/local/libtorch/lib/libtorch_cpu.so" -Wl,--as-needed -lpthread /usr/local/libtorch/lib/libc10_cuda.so /usr/local/libtorch/lib/libc10.so /usr/local/cuda-11.2/lib64/libcufft.so /usr/local/cuda-11.2/lib64/libcurand.so /usr/local/cuda-11.2/lib64/libcublas.so /usr/local/cuda-11.2/lib64/libcudnn.so -Wl,--no-as-needed,"/usr/local/libtorch/lib/libtorch_cuda_cu.so" -Wl,--as-needed -Wl,--no-as-needed,"/usr/local/libtorch/lib/libtorch.so" -Wl,--as-needed -lnvToolsExt /usr/local/cuda-11.2/lib64/libcudart.so 
/usr/bin/ld: CMakeFiles/hello_world.dir/src/app.cpp.o: in function `main':
app.cpp:(.text+0x292): undefined reference to `onmt::Tokenizer::joiner_marker'
/usr/bin/ld: app.cpp:(.text+0x2a7): undefined reference to `onmt::Tokenizer::Tokenizer(onmt::Tokenizer::Mode, int, std::string const&, std::string const&, std::string const&, int)'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/hello_world.dir/build.make:114: ../bin/hello_world] Error 1
make[2]: Leaving directory '/home/inez/Projects/cmake_hello_world/build'
make[1]: *** [CMakeFiles/Makefile2:83: CMakeFiles/hello_world.dir/all] Error 2
make[1]: Leaving directory '/home/inez/Projects/cmake_hello_world/build'
make: *** [Makefile:91: all] Error 2

Torch 有一个 TorchConfig.make

# Finds the Torch library
#
# This will define the following variables:
#
#   TORCH_FOUND        -- True if the system has the Torch library
#   TORCH_INCLUDE_DIRS -- The include directories for torch
#   TORCH_LIBRARIES    -- Libraries to link against
#   TORCH_CXX_FLAGS    -- Additional (required) compiler flags

来自LINK_LIBRARIES的链接库

LINK_LIBRARIES=torchtorch_library/usr/local/libtorch/lib/libc10.so/usr/local/libtorch/lib/libkineto.a/usr/local/cuda-11.2/lib64/stubs/libcuda.so/usr/local/cuda-11.2/lib64/libnvrtc.so/usr/lib/x86_64-linux-gnu/libnvToolsExt.so/usr/local/cuda-11.2/lib64/libcudart.so/usr/local/libtorch/lib/libc10_cuda.soOpenNMTTokenizer

请看下面的答案

这些库链接到不同的标准库。正如 @botje 所建议的，_GLIBCXX_USE_CXX11_ABI 的值不匹配。

我用这一行重新编译了OpenNMTTokenizer，然后主项目编译没有错误：

add_compile_definitions(_GLIBCXX_USE_CXX11_ABI=0)

来自 libstdc++

如果您收到有关未定义符号引用的链接器错误，这些符号涉及 std::__cxx11 命名空间或标签 [abi:cxx11] 中的类型，则可能表明您正在尝试将使用不同值编译的目标文件链接在一起_GLIBCXX_USE_CXX11_ABI 宏。

这通常发生在链接到第三方库时 使用旧版本的 GCC 编译。如果第三方库 无法使用新的 ABI 重建，那么您将需要重新编译 旧 ABI 的代码。

Read more at gnu.org

Answer 1

正如 cmets 中所讨论的，事实证明其中一个组件（OpenNMTTokenizer）是使用 CXX11 ABI 编译的，而另外两个（Torch 和 app.cpp）不是。这导致符号名称不匹配。

直接的解决方法是在没有 CXX11 ABI 的情况下重新编译 OpenNMTTokenizer，尽管正确的解决方法是使用 CXX11 ABI 编译所有内容。这意味着重新编译 Torch。