Question

我确信之前已经提出过这个问题，但我已经尽可能多地搜索了SO，但仍然无法找到错误的确切原因。因此发布一个新的。

我在项目中使用C ++库（txmpp）。该库已正确添加，但我得到了许多未解决的外部符号问题，主要是在我尝试使用的类的构造函数中。例如，在以下类中 -

xmppthread.h

#ifndef _HELLO_XMPPTHREAD_H_
#define _HELLO_XMPPTHREAD_H_

#include "../../thread.h"
#include "../../xmppclientsettings.h"
#include "xmpppump.h"

namespace txmpp {

class XmppThread: public txmpp::Thread, XmppPumpNotify, txmpp::MessageHandler {
  public:
    XmppThread();
    ~XmppThread();

    XmppClient* client() { return pump_->client(); }

    void ProcessMessages(int cms);
    void Login(const txmpp::XmppClientSettings & xcs);
    void Disconnect();

  private:
    XmppPump* pump_;

    void OnStateChange(txmpp::XmppEngine::State state);
    void OnMessage(txmpp::Message* pmsg);
};

}  // namespace txmpp

#endif  // _HELLO_XMPPTHREAD_H_

xmppthread.cc

#include "xmppthread.h"

#include <assert.h>
#include "../../prexmppauthimpl.h"
#include "../../xmppasyncsocketimpl.h"
#include "../../xmppclientsettings.h"

namespace txmpp {
namespace {

const uint32 MSG_LOGIN = 1;
const uint32 MSG_DISCONNECT = 2;

struct LoginData : public MessageData {
  LoginData(const XmppClientSettings& s) : xcs(s) {}
  virtual ~LoginData() {}
  XmppClientSettings xcs;
};

} // namespace

XmppThread::XmppThread() {
  pump_ = new XmppPump(this);
}

XmppThread::~XmppThread() {
  delete pump_;
}

void XmppThread::ProcessMessages(int cms) {
  Thread::ProcessMessages(cms);
}

void XmppThread::Login(const XmppClientSettings& xcs) {
  Post(this, MSG_LOGIN, new LoginData(xcs));
}

void XmppThread::Disconnect() {
  Post(this, MSG_DISCONNECT);
}

void XmppThread::OnStateChange(XmppEngine::State state) {
}

void XmppThread::OnMessage(Message* pmsg) {
  switch (pmsg->message_id) {
    case MSG_LOGIN: {
      assert(pmsg->pdata);
      LoginData* data = reinterpret_cast<LoginData*>(pmsg->pdata);
      pump_->DoLogin(data->xcs, new XmppAsyncSocketImpl(true),
                     new PreXmppAuthImpl());
      delete data;
      }
      break;
    case MSG_DISCONNECT:
      pump_->DoDisconnect();
      break;
    default:
      assert(false);
  }
}

}  // namespace hello

我收到以下错误 -

1>XMPPController.obj : error LNK2019: unresolved external symbol "public: __thiscall txmpp::XmppThread::XmppThread(void)" (??0XmppThread@txmpp@@QAE@XZ) referenced in function "public: void __thiscall XMPPController::Init(void)" (?Init@XMPPController@@QAEXXZ)
1>XMPPController.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall txmpp::XmppThread::~XmppThread(void)" (??1XmppThread@txmpp@@UAE@XZ) referenced in function "public: void __thiscall XMPPController::Init(void)" (?Init@XMPPController@@QAEXXZ)

我通常只在未提供函数定义（本例中为构造函数/析构函数）时才会看到此类链接器错误。但是，您可以看到包含的定义。只有在我的项目中执行此操作时才会生成此错误 -

xmpp::XmppThread thread;

一旦删除声明语句，就会出现链接错误。问题是这些代码都不是由我编写的，而是从txmpp库中获取的。这个特殊的课程来自Google的libjingle图书馆，所以我相信我在这里犯了一些非常愚蠢的错误。

我不希望这个问题成为＆＃34;这是我的代码，解决问题＆＃34;一。相反，我想知道尽管有声明，可能出现未解决的外部符号错误的情况是什么？（代码是为了提供实现的证据）

有什么建议吗？

更新
这是关闭supress启动横幅选项后我得到的确切输出 -

 1>LINK : warning LNK4075: ignoring '/INCREMENTAL' due to '/FORCE' specification
    1>AirPlaySystem.obj : warning LNK4075: ignoring '/EDITANDCONTINUE' due to '/OPT:LBR' specification
    1>LIBCMTD.lib(sscanf.obj) : warning LNK4006: _vsscanf already defined in s3e_d.lib(iwcrt_win32.obj); second definition ignored
    1>LIBCMTD.lib(strtoq.obj) : warning LNK4006: _strtof already defined in s3e_d.lib(iwcrt_common.obj); second definition ignored
    1>     Creating library Debug_BarnC_vc12_x86\BarnC.lib and object Debug_BarnC_vc12_x86\BarnC.exp
    1>XMPPController.obj : error LNK2019: unresolved external symbol "public: __thiscall txmpp::XmppThread::XmppThread(void)" (??0XmppThread@txmpp@@QAE@XZ) referenced in function "public: void __thiscall XMPPController::Init(void)" (?Init@XMPPController@@QAEXXZ)
    1>XMPPController.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall txmpp::XmppThread::~XmppThread(void)" (??1XmppThread@txmpp@@UAE@XZ) referenced in function "public: void __thiscall XMPPController::Init(void)" (?Init@XMPPController@@QAEXXZ)
    1>Debug_BarnC_vc12_x86\BarnC.s86 : fatal error LNK1120: 2 unresolved externals
    ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

更新2： 这是添加详细链接器命令行选项 -

后的详细链接器输出

1>  Microsoft (R) Incremental Linker Version 12.00.31101.0
1>  Copyright (C) Microsoft Corporation.  All rights reserved.
1>  
1>  "/OUT:Debug_BarnC_vc12_x86\BarnC.s86" /INCREMENTAL /LIBPATH:d:/marmalade/7.4/modules/third_party/sqlite/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwutil/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/third_party/libjpeg/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/third_party/zlib/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/third_party/libpng/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iw2d/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwgx/atitools /LIBPATH:d:/marmalade/7.4/modules/iwgx/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwgl/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwgeom/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwresmanager/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwgxfont/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/third_party/tiniconv/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwui/lib/x86 /LIBPATH:d:/marmalade/7.4/modules/iwhttp/lib/x86 /LIBPATH:d:/marmalade/7.4/extensions/s3etxmpp/lib/x86 /LIBPATH:d:/marmalade/7.4/s3e/lib/x86 vc6_compat.lib sqlite_d.lib iwutil_d.lib jpeg_d.lib z_d.lib png_d.lib iw2d_d.lib ATI_Compress_MT_VC7.lib iwgx_d.lib iwgl_d.lib iwgeom_d.lib iwresmanager_d.lib iwgxfont_ttf_d.lib tiniconv_d.lib iwui_d.lib iwhttp_d.lib s3eTxmpp_d.lib s3e_cpp_d.lib s3e_d.lib s3e_api_iwgl.lib /NODEFAULTLIB:libcmt /MANIFEST:NO /DEBUG "/PDB:Debug_BarnC_vc12_x86\BarnC.pdb" /SUBSYSTEM:WINDOWS /OPT:NOREF /OPT:NOICF /TLBID:1 "/ENTRY:DllEntryPoint" /DYNAMICBASE /NXCOMPAT "/IMPLIB:Debug_BarnC_vc12_x86\BarnC.lib" /MACHINE:X86 /include:_IwMain /include:_raise /include:_DllEntryPoint@12 /force:multiple /VERBOSE:LIB /DLL Debug_BarnC_vc12_x86\AirPlaySystem.obj 
1>  Debug_BarnC_vc12_x86\CTextField.obj 
1>  Debug_BarnC_vc12_x86\Chat.obj 
1>  Debug_BarnC_vc12_x86\ChatController.obj 
1>  Debug_BarnC_vc12_x86\ChatGroup.obj 
1>  Debug_BarnC_vc12_x86\ChatMenu.obj 
1>  Debug_BarnC_vc12_x86\Contact.obj 
1>  Debug_BarnC_vc12_x86\ContactController.obj 
1>  Debug_BarnC_vc12_x86\HttpManager.obj 
1>  Debug_BarnC_vc12_x86\LoginMenu.obj 
1>  Debug_BarnC_vc12_x86\Main.obj 
1>  Debug_BarnC_vc12_x86\MainMenu.obj 
1>  Debug_BarnC_vc12_x86\MenuBase.obj 
1>  Debug_BarnC_vc12_x86\MenuController.obj 
1>  Debug_BarnC_vc12_x86\PVRTexTool_interface.obj 
1>  Debug_BarnC_vc12_x86\SimpleTouch.obj 
1>  Debug_BarnC_vc12_x86\UnivApp.obj 
1>  Debug_BarnC_vc12_x86\XMPPController.obj 
1>  Debug_BarnC_vc12_x86\md5c.obj 
1>LINK : warning LNK4075: ignoring '/INCREMENTAL' due to '/FORCE' specification
1>AirPlaySystem.obj : warning LNK4075: ignoring '/EDITANDCONTINUE' due to '/OPT:LBR' specification
1>  
1>  Searching libraries
1>      Searching d:/marmalade/7.4/modules/third_party/sqlite/lib/x86\sqlite_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwutil/lib/x86\iwutil_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libjpeg/lib/x86\jpeg_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/zlib/lib/x86\z_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libpng/lib/x86\png_d.lib:
1>      Searching d:/marmalade/7.4/modules/iw2d/lib/x86\iw2d_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/atitools\ATI_Compress_MT_VC7.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/lib/x86\iwgx_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgl/lib/x86\iwgl_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgeom/lib/x86\iwgeom_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwresmanager/lib/x86\iwresmanager_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgxfont/lib/x86\iwgxfont_ttf_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/tiniconv/lib/x86\tiniconv_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwui/lib/x86\iwui_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwhttp/lib/x86\iwhttp_d.lib:
1>      Searching d:/marmalade/7.4/extensions/s3etxmpp/lib/x86\s3eTxmpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_cpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_api_iwgl.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\OLDNAMES.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\LIBCMTD.lib:
1>LIBCMTD.lib(sscanf.obj) : warning LNK4006: _vsscanf already defined in s3e_d.lib(iwcrt_win32.obj); second definition ignored
1>LIBCMTD.lib(strtoq.obj) : warning LNK4006: _strtof already defined in s3e_d.lib(iwcrt_common.obj); second definition ignored
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\uuid.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\kernel32.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/sqlite/lib/x86\sqlite_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwutil/lib/x86\iwutil_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libjpeg/lib/x86\jpeg_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/zlib/lib/x86\z_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libpng/lib/x86\png_d.lib:
1>      Searching d:/marmalade/7.4/modules/iw2d/lib/x86\iw2d_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/atitools\ATI_Compress_MT_VC7.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/lib/x86\iwgx_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgl/lib/x86\iwgl_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgeom/lib/x86\iwgeom_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwresmanager/lib/x86\iwresmanager_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgxfont/lib/x86\iwgxfont_ttf_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/tiniconv/lib/x86\tiniconv_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwui/lib/x86\iwui_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwhttp/lib/x86\iwhttp_d.lib:
1>      Searching d:/marmalade/7.4/extensions/s3etxmpp/lib/x86\s3eTxmpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_cpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_api_iwgl.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\OLDNAMES.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\LIBCMTD.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\uuid.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\kernel32.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/sqlite/lib/x86\sqlite_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwutil/lib/x86\iwutil_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libjpeg/lib/x86\jpeg_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/zlib/lib/x86\z_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libpng/lib/x86\png_d.lib:
1>      Searching d:/marmalade/7.4/modules/iw2d/lib/x86\iw2d_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/atitools\ATI_Compress_MT_VC7.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/lib/x86\iwgx_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgl/lib/x86\iwgl_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgeom/lib/x86\iwgeom_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwresmanager/lib/x86\iwresmanager_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgxfont/lib/x86\iwgxfont_ttf_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/tiniconv/lib/x86\tiniconv_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwui/lib/x86\iwui_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwhttp/lib/x86\iwhttp_d.lib:
1>      Searching d:/marmalade/7.4/extensions/s3etxmpp/lib/x86\s3eTxmpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_cpp_d.lib:
1>  
1>  Finished searching libraries
1>     Creating library Debug_BarnC_vc12_x86\BarnC.lib and object Debug_BarnC_vc12_x86\BarnC.exp
1>  
1>  Searching libraries
1>      Searching d:/marmalade/7.4/modules/third_party/sqlite/lib/x86\sqlite_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwutil/lib/x86\iwutil_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libjpeg/lib/x86\jpeg_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/zlib/lib/x86\z_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libpng/lib/x86\png_d.lib:
1>      Searching d:/marmalade/7.4/modules/iw2d/lib/x86\iw2d_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/atitools\ATI_Compress_MT_VC7.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/lib/x86\iwgx_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgl/lib/x86\iwgl_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgeom/lib/x86\iwgeom_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwresmanager/lib/x86\iwresmanager_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgxfont/lib/x86\iwgxfont_ttf_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/tiniconv/lib/x86\tiniconv_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwui/lib/x86\iwui_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwhttp/lib/x86\iwhttp_d.lib:
1>      Searching d:/marmalade/7.4/extensions/s3etxmpp/lib/x86\s3eTxmpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_cpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_api_iwgl.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\OLDNAMES.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\LIBCMTD.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\uuid.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\kernel32.lib:
1>  
1>  Finished searching libraries
1>  
1>  Searching libraries
1>      Searching d:/marmalade/7.4/modules/third_party/sqlite/lib/x86\sqlite_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwutil/lib/x86\iwutil_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libjpeg/lib/x86\jpeg_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/zlib/lib/x86\z_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/libpng/lib/x86\png_d.lib:
1>      Searching d:/marmalade/7.4/modules/iw2d/lib/x86\iw2d_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/atitools\ATI_Compress_MT_VC7.lib:
1>      Searching d:/marmalade/7.4/modules/iwgx/lib/x86\iwgx_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgl/lib/x86\iwgl_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgeom/lib/x86\iwgeom_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwresmanager/lib/x86\iwresmanager_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwgxfont/lib/x86\iwgxfont_ttf_d.lib:
1>      Searching d:/marmalade/7.4/modules/third_party/tiniconv/lib/x86\tiniconv_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwui/lib/x86\iwui_d.lib:
1>      Searching d:/marmalade/7.4/modules/iwhttp/lib/x86\iwhttp_d.lib:
1>      Searching d:/marmalade/7.4/extensions/s3etxmpp/lib/x86\s3eTxmpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_cpp_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_d.lib:
1>      Searching d:/marmalade/7.4/s3e/lib/x86\s3e_api_iwgl.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\OLDNAMES.lib:
1>      Searching C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\lib\LIBCMTD.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\uuid.lib:
1>      Searching C:\Program Files (x86)\Windows Kits\8.1\lib\winv6.3\um\x86\kernel32.lib:
1>  
1>  Finished searching libraries
1>XMPPController.obj : error LNK2019: unresolved external symbol "public: __thiscall txmpp::XmppThread::XmppThread(void)" (??0XmppThread@txmpp@@QAE@XZ) referenced in function "public: void __thiscall XMPPController::Init(void)" (?Init@XMPPController@@QAEXXZ)
1>XMPPController.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall txmpp::XmppThread::~XmppThread(void)" (??1XmppThread@txmpp@@UAE@XZ) referenced in function "public: void __thiscall XMPPController::Init(void)" (?Init@XMPPController@@QAEXXZ)
1>Debug_BarnC_vc12_x86\BarnC.s86 : fatal error LNK1120: 2 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

Marmalade（我用来构建此项目的SDK工具链）无法将.cc文件识别为源文件。我将它们改为.cpp，然后他们就被识别出来了。但是，库中仍然存在很多错误，但至少我知道如何解决它们。谢谢你的帮助。

尽管在cpp中有定义，但LNK2019在构造函数中未解析外部符号

1 个答案: