c++ - 找不到体系结构 x86_64 的符号 - Cmake - Mac sierra

Question

最近我开始了一个新的 C++ 项目。问题是，当我尝试编译它时出现链接错误。我今天花了一整天试图调试它，但我并没有真正找到一个好的解决方案。如果有人可以提供帮助，那就太棒了。我使用的是 Mac Sierra。

解析/甲基化.h

#ifndef EPIRL_METHYLATION_H
#define EPIRL_METHYLATION_H

#include <stdio.h>
#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>

using namespace std;

namespace methylation {
    struct MethLine {
        string chr;
        int coord;
        char strand;
        int methylated;
        int un_methylated;
        string context;
        string tag;
    };

    string calculateMethylationByContext(
            MethLine m_input[], int length,
            int window_start, int window_end, int threshold);

    void calculateMethylation(
        const istream &methylation_stream,
        const istream &coordinate_stream,
        const ostream &output_stream
    );
}

#endif //EPIRL_METHYLATION_H

解析/甲基化.cpp

#include "methylation.h"

namespace methylation {
    string calculateMethylationByContext(
            MethLine m_input[], int length,
            int window_start, int window_end, int threshold) {
// rest of the code ...
    }
}

main.cpp

#include <iostream>
#include <fstream>
#include "parsing/methylation.h"

using namespace std;

int main(int argc, char **argv) {
    if (argc != 4) {
        cout << "Invalid number of arguments..." << endl;
        return 1;
    }

    char *methylation_file = argv[1];
    char *coordinate_file = argv[2];
    char *output_file = argv[3];

    ifstream methylation_file_stream(methylation_file, ios::binary);
    ifstream coordinate_file_stream(coordinate_file, ios::binary);
    ofstream output_file_stream(output_file, ios::binary);

    methylation::calculateMethylation(methylation_file_stream,
                         coordinate_file_stream, output_file_stream);
    methylation_file_stream.close();
    coordinate_file_stream.close();
    output_file_stream.close();

    return 0;
}

我使用 CLion 进行编码。当我尝试构建它时，我的 cmake 命令工作正常，但是当我单击“make”时，出现以下错误:

Undefined symbols for architecture x86_64:
  "methylation::calculateMethylation(std::__1::basic_istream<char, std::__1::char_traits<char> > const&, std::__1::basic_istream<char, std::__1::char_traits<char> > const&, std::__1::basic_ostream<char, std::__1::char_traits<char> > const&)", referenced from:
      _main in main.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [src] Error 1
make[2]: *** [CMakeFiles/src.dir/all] Error 2
make[1]: *** [CMakeFiles/src.dir/rule] Error 2
make: *** [src] Error 2

我的 CMakeLists.txt 文件如下所示:

cmake_minimum_required(VERSION 3.6)
project(src)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")

set(SOURCE_FILES
    parsing/methylation.cpp
    parsing/methylation.h
    main.cpp)

add_executable(src ${SOURCE_FILES})

当我运行 cmake 命令时，我的输出是这样的:

-- The C compiler identification is AppleClang 8.0.0.8000042
-- The CXX compiler identification is AppleClang 8.0.0.8000042
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc
-- Check for working C compiler: /Library/Developer/CommandLineTools/usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++
-- Check for working CXX compiler: /Library/Developer/CommandLineTools/usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/sztankatt/Documents/University/PartIII/Project/epiRL/src

Answer 1

您的 CMakeLists.txt 没问题。

正如@thomas-matthews @tsyvarev @nos 在他们的评论中指出的那样，您的示例代码缺少 methylation::calculateMethylation() 的定义/实现。在这种情况下，您看到的是 Apple/clang 的预期失败。

❯ make
[ 33%] Building CXX object CMakeFiles/src.dir/parsing/methylation.cpp.o
/Users/nega/foo/parsing/methylation.cpp:8:5: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^
1 warning generated.
[ 66%] Building CXX object CMakeFiles/src.dir/main.cpp.o
[100%] Linking CXX executable src
Undefined symbols for architecture x86_64:
  "methylation::calculateMethylation(std::__1::basic_istream<char, std::__1::char_traits<char> > const&, std::__1::basic_istream<char, std::__1::char_traits<char> > const&, std::__1::basic_ostream<char, std::__1::char_traits<char> > const&)", referenced from:
      _main in main.cpp.o
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] Error 1
make[1]: *** [CMakeFiles/src.dir/all] Error 2
make: *** [all] Error 2

添加虚拟实现，或在 main.cpp 中注释掉调用，将允许 make 成功完成。

假设你有一个正确的实现

假设您确实在代码中(可能在另一个文件中)实现了 methylation::calculateMethylation()。在 CMake 生成的 Makefile 中调试构建错误的第一步是在 make 变量 VERBOSE 设置为真值的情况下运行，即:make VERBOSE=1。

❯ make VERBOSE=1
/usr/local/Cellar/cmake/3.7.0/bin/cmake -H/Users/nega/foo -B/Users/nega/foo/build --check-build-system CMakeFiles/Makefile.cmake 0
/usr/local/Cellar/cmake/3.7.0/bin/cmake -E cmake_progress_start /Users/nega/foo/build/CMakeFiles /Users/nega/foo/build/CMakeFiles/progress.marks
/Applications/Xcode.app/Contents/Developer/usr/bin/make -f CMakeFiles/Makefile2 all
/Applications/Xcode.app/Contents/Developer/usr/bin/make -f CMakeFiles/src.dir/build.make CMakeFiles/src.dir/depend
cd /Users/nega/foo/build && /usr/local/Cellar/cmake/3.7.0/bin/cmake -E cmake_depends "Unix Makefiles" /Users/nega/foo /Users/nega/foo /Users/nega/foo/build /Users/nega/foo/build /Users/nega/foo/build/CMakeFiles/src.dir/DependInfo.cmake --color=
/Applications/Xcode.app/Contents/Developer/usr/bin/make -f CMakeFiles/src.dir/build.make CMakeFiles/src.dir/build
[ 33%] Building CXX object CMakeFiles/src.dir/parsing/methylation.cpp.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++     -std=gnu++11 -o CMakeFiles/src.dir/parsing/methylation.cpp.o -c /Users/nega/foo/parsing/methylation.cpp
/Users/nega/foo/parsing/methylation.cpp:8:5: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^
1 warning generated.
[ 66%] Building CXX object CMakeFiles/src.dir/main.cpp.o
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++     -std=gnu++11 -o CMakeFiles/src.dir/main.cpp.o -c /Users/nega/foo/main.cpp
[100%] Linking CXX executable src
/usr/local/Cellar/cmake/3.7.0/bin/cmake -E cmake_link_script CMakeFiles/src.dir/link.txt --verbose=1
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++    -Wl,-search_paths_first -Wl,-headerpad_max_install_names  CMakeFiles/src.dir/parsing/methylation.cpp.o CMakeFiles/src.dir/main.cpp.o  -o src 
Undefined symbols for architecture x86_64:
  "methylation::calculateMethylation(std::__1::basic_istream<char, std::__1::char_traits<char> > const&, std::__1::basic_istream<char, std::__1::char_traits<char> > const&, std::__1::basic_ostream<char, std::__1::char_traits<char> > const&)", referenced from:
      _main in main.cpp.o
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] Error 1
make[1]: *** [CMakeFiles/src.dir/all] Error 2
make: *** [all] Error 2

现在您可以查看链接步骤，看看您是否遗漏了项目；也许是一个库，或者一个目标文件。如果是这样，现在您知道返回并将其添加到您的 CMakeLists.txt

总结

使用 CMake 生成的 Makefile 调试意外构建失败的第一步是运行:

❯ make VERBOSE=1

这将使您深入了解 CMake 在幕后所做的事情。