C++ -未定义的符号链接器错误- Xcode

Question

我有三个C++文件，我得到了一个非常恼人的C++链接器错误。下面是错误：

Undefined symbols for architecture x86_64:
  "tiled::debug::log(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from:
  _main in main.o
  error_callback(int, char const*) in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

以下是我的文件：

main.cpp

#include "debug.hpp"
#include <GLFW/glfw3.h>

using namespace tiled;

void error_callback(int error, const char* description);

int main(int argc, char* argv[])
{
    debug::log("Initializing");
    glfwSetErrorCallback(error_callback);

    debug::log("Initializing GLFW...");
    if (!glfwInit())
    {
        debug::log("Failed to initialize GLFW!");

        glfwTerminate();
        return -1;
    }
    debug::log("Done");

    debug::log("Exiting program!");
    glfwTerminate();
    return 0;
}

void error_callback(int error, const char* description)
{
    std::string error_code;
    error_code.append("GLFW error ");
    error_code.append(std::to_string(error));

    debug::log(error_code);
    debug::log(description);
}

debug.hpp

#ifndef TILED_DEBUG_HPP
#define TILED_DEBUG_HPP

#include <ctime>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>

namespace tiled
{
    class debug {
    private:
        static std::vector<std::string> data;
        static std::ofstream log_file;

    public:
        static void log(const std::string& msg);
        static int write_logs();
    };
}

#endif /* TILED_DEBUG_HPP */

还有，debug.cpp

#include "debug.hpp"

namespace tiled
{
    void debug::log (const std::string& msg)
    {
        // Log to the console
        std::cout << msg << std::endl;
        // Add to the data we will put in the log file.
        data.push_back(msg);
    }

    int debug::write_logs()
    {
        std::string data_str;

        /*
         We get the system time here. This is because we want to name each log
         after what time the log file was made.
         */
        std::time_t result = std::time(nullptr);
        std::string time = std::asctime(std::localtime(&result));

        data_str.append("\n");
        data_str.append(time);

        // Put the contents of the data vector into the string we append to file
        for (std::string str : data)
        {
            data_str.append("\n");
            data_str.append(str);
        }

        log_file.open(time.c_str(), std::ios::app);

        if (log_file.is_open())
        {
            log_file << data_str;
            log_file.close();
        }
        else
        {
            std::cout << "Error: Couldn't write log file!" << std::endl;
            return 1;
        }

        return 0;
    }
}

函数日志似乎没有定义，但我在debug.cpp文件中定义了它。我已经为此工作了几个小时了.有谁可以帮我？

另外，以下是Xcode使用构建程序的命令：

Ld /Users/home/Library/Developer/Xcode/DerivedData/tiled-bhqwfqpsuugzhkagbmrhebnbgnpb/Build/Products/Debug/tiled normal /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk cd /Users/home/Documents/tiled x86_64 MACOSX_DEPLOYMENT_TARGET=10.10 -arch x86_64 -isysroot Ld -L/Users/home/Library/Developer/Xcode/DerivedData/tiled-bhqwfqpsuugzhkagbmrhebnbgnpb/Build/Products/Debug -L/usr/local/lib -F/Users/home/Library/Developer/Xcode/DerivedData/tiled-bhqwfqpsuugzhkagbmrhebnbgnpb/Build/Products/Debug版本/Users/home/Library/Developer/Xcode/DerivedData/tiled-bhqwfqpsuugzhkagbmrhebnbgnpb/Build/Intermediates/tiled.build/Debug/tiled.build/Objects-normal/x86_64/tiled.LinkFileList -mmacosx- -filelist --filelist=10.10 -stdlib=libc++ -lglfw.3.1 -framework OpenGL -Xlinker -dependency_info -Xlinker /Users/home/Library/Developer/Xcode/DerivedData/tiled-bhqwfqpsuugzhkagbmrhebnbgnpb/Build/Intermediates/tiled.build/Debug/tiled.build/Objects-normal/x86_64/tiled_dependency_info.dat -o /Users/home/Library/Developer/Xcode/DerivedData/tiled-bhqwfqpsuugzhkagbmrhebnbgnpb/Build/Products/Debug/tile

Answer 1

为了解决这个问题，我去掉了.cpp文件，只制作了那些内联函数。因为这只是一个变通方法，所以我不会选择这个作为答案。