在 OSx 上使用 CMake 构建 C++ 项目： ld: symbol(s) not found for architecture x86_64

Question

我获得了一个使用 Xerces-C++ 的旧 C++ 项目的源代码，我正在尝试使用 CMake 在 CLion 上构建该项目。 OSx 版本：Catalina。

我首先准备了旧项目中没有的 CMakeLists.txt。

我遇到了这个构建异常：

/Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake --build /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug --target all -- -j 4 VERBOSE=1
/Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake -S/Users/miloscuculovic/CLionProjects/Test2 -B/Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug --check-build-system CMakeFiles/Makefile.cmake 0
/Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake -E cmake_progress_start /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug/CMakeFiles /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug/CMakeFiles/progress.marks
/Library/Developer/CommandLineTools/usr/bin/make -f CMakeFiles/Makefile2 all
/Library/Developer/CommandLineTools/usr/bin/make -f src/CMakeFiles/Test2.dir/build.make src/CMakeFiles/Test2.dir/depend
cd /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug && /Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake -E cmake_depends "Unix Makefiles" /Users/miloscuculovic/CLionProjects/Test2 /Users/miloscuculovic/CLionProjects/Test2/src /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug/src /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug/src/CMakeFiles/Test2.dir/DependInfo.cmake --color=
/Library/Developer/CommandLineTools/usr/bin/make -f src/CMakeFiles/Test2.dir/build.make src/CMakeFiles/Test2.dir/build
[ 50%] Linking CXX executable Test2
cd /Users/miloscuculovic/CLionProjects/Test2/cmake-build-debug/src && /Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake -E cmake_link_script CMakeFiles/Test2.dir/link.txt --verbose=1
/Library/Developer/CommandLineTools/usr/bin/c++  -g -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names  CMakeFiles/Test2.dir/ComputeDelta.cpp.o  -o Test2 -framework CoreFoundation -framework CoreFoundation -framework IOKit /usr/lib/libobjc.dylib /usr/lib/libcurl.dylib 
Undefined symbols for architecture x86_64:
  "xercesc_3_2::XMLAttDefList::serialize(xercesc_3_2::XSerializeEngine&)", referenced from:
      vtable for xercesc_3_2::XMLAttDefList in ComputeDelta.cpp.o
  "NodesManager::PrintStats()", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::FullBottomUp(int)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::topdownMatch(int, int)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::setUniqueIdHandler(UniqueIdHandler*)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::registerResultDocument(XID_DOMDocument*)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::registerSourceDocument(XID_DOMDocument*)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::Optimize(int)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::MatchById(int)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::NodesManager()", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "NodesManager::~NodesManager()", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "DeltaConstructor::getDeltaDocument()", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "DeltaConstructor::constructDeltaDocument()", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "DeltaConstructor::DeltaConstructor(NodesManager*, char const*, XID_DOMDocument*, char const*, XID_DOMDocument*, bool)", referenced from:
      XidXyDiff(XID_DOMDocument*, char const*, XID_DOMDocument*, char const*, bool, bool) in ComputeDelta.cpp.o
  "xercesc_3_2::XMLAttDefList::getProtoType() const", referenced from:
      vtable for xercesc_3_2::XMLAttDefList in ComputeDelta.cpp.o
  "xercesc_3_2::XMLAttDefList::isSerializable() const", referenced from:
      vtable for xercesc_3_2::XMLAttDefList in ComputeDelta.cpp.o
  "_main", referenced from:
     implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [src/Test2] Error 1
make[1]: *** [src/CMakeFiles/Test2.dir/all] Error 2
make: *** [all] Error 2

有两个CMakeLists.txt文件，一个在项目根目录，第二个在src：

根目录下的 CMakeLists.txt：

cmake_minimum_required(VERSION 3.15)
project(Test2)

set(CMAKE_CXX_STANDARD 14)

add_subdirectory(src)

CMakeLists.txt 在 src:

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
include_directories(${CMAKE_CURRENT_SOURCE_DIR})
include_directories(/usr/local/Cellar/xerces-c/3.2.2/include)
include_directories(/usr/local/Cellar/opencascade/7.3.0p3/include)
include_directories(/usr/local/Cellar/libuv/1.31.0/include)

add_executable(Test2 ComputeDelta.cpp)

set(STLINK_LIB_SHARED ${PROJECT_NAME})
find_library(ObjC objc)
find_library(Curl curl)
find_library(CoreServices CoreServices)
find_library(CoreFoundation CoreFoundation)
find_library(IOKit IOKit)
target_link_libraries(${STLINK_LIB_SHARED} ${CoreServices} ${CoreFoundation} ${IOKit} ${ObjC} ${Curl})

知道如何解决这个问题吗？我已经安装了opencascade、libuv、libev。

Answer 1

libuv 和 xerces-c 都有一个 pkg-config (.pc) 文件，因此您可以将 CMakeLists.txt 缩减为以下内容。这利用了FindPkgConfig 模块，该模块将 pkg-config 文件转换为 IMPORTED 目标（请参阅"It's time to do CMake right"。这个 IMPORTED 目标将自动知道要包含哪些标头以及要链接哪些库，您只需要使用 target_link_libraries链接。

include(FindPkgConfig)
pkg_check_modules(Xerces REQUIRED IMPORTED_TARGET xerces-c)
pkg_check_modules(LibUv REQUIRED IMPORTED_TARGET libuv)

include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
include_directories(${CMAKE_CURRENT_SOURCE_DIR})
include_directories(/usr/local/Cellar/opencascade/7.3.0p3/include)

add_library(libxyDelta STATIC
                convertUTF.cpp
                StringPusher.cpp 
                ComputeDelta.cpp
                Diff_DeltaConstructor.pp 
                Diff_NodesManager.cpp 
                Diff_UniqueIdHandler.cpp 
                DeltaApply.cpp 
                DeltaException.cpp 
                DeltaManager.cpp 
                DeltaReverse.cpp 
                DeltaSortOperations.cpp 
                easy_css.cpp 
                lcss.cpp 
                lookup2.cpp 
                Tools.cpp 
                XID_map.cpp 
                XID_DOMDocument.cpp 
                XyDeltaFileImpl.cpp 
                XyDeltaDomImpl.cpp 
                XyInt.cpp 
                XyLatinStr.cpp 
                XyStr.cpp
                XyStrDiff.cpp
                XyStrDelta.cpp
                XyUTF8Str.cpp)

set(STLINK_LIB_SHARED ${PROJECT_NAME})
find_library(ObjC objc)
find_library(Curl curl)
find_library(CoreServices CoreServices)
find_library(CoreFoundation CoreFoundation)
find_library(IOKit IOKit)
target_link_libraries(libxyDelta ${CoreServices} ${CoreFoundation} ${IOKit} ${ObjC} ${Curl})
target_link_libraries(libxyDelta PkgConfig::LibUv PkgConfig::Xerces)

add_executable(xydiff execComputeDelta.cpp)
target_link_libraries(xydiff libxyDelta)
add_executable(xydelta execDeltaApply.cpp)
target_link_libraries(xydelta libxyDelta)

我还将您的add_executable 更改为add_library。 总之，这将消除有关 xerces 和 main 的任何错误。这只会给您留下关于 NodesManager 和 DeltaConstructor 的错误，但我认为这些错误位于您忘记添加到目标的单独 .cpp 文件中。

您可能也可以摆脱大多数 find_libraries 调用，但如果不知道您的源文件是什么样的，我就无法做到这一点。