如何让VS2008在C++项目中使用__cdecl而不是__thiscall？

Question

我正在尝试在Visual Studio2008中构建一个开源的C++项目。我加载了解决方案文件，一切都被编译了，但由于找不到某些方法，我得到了一堆链接错误。在使用DUMPBIN.EXE检查了有问题的.lib文件之后，我可以看到问题出在哪里：.lib中的方法在其签名中都有__cdecl，而链接器正在寻找具有__thiscall的等效方法。

怎样才能让VS2008使用__cdecl呢？

注:该项目是一个基于OpenCV的多点触摸跟踪程序a fork of CCV。此分支的目的是通过相机制造商提供的FlyCapture2库为名为Flea3的相机提供支持。以下是链接器错误：

1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall FlyCapture2::Image::Image(void)" (__imp_??0Image@FlyCapture2@@QAE@XZ) referenced in function "public: __thiscall ofxFlea3::ofxFlea3(void)" (??0ofxFlea3@@QAE@XZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall FlyCapture2::Image::~Image(void)" (__imp_??1Image@FlyCapture2@@UAE@XZ) referenced in function "public: __thiscall ofxFlea3::ofxFlea3(void)" (??0ofxFlea3@@QAE@XZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall FlyCapture2::Camera::Camera(void)" (__imp_??0Camera@FlyCapture2@@QAE@XZ) referenced in function "public: __thiscall ofxFlea3::ofxFlea3(void)" (??0ofxFlea3@@QAE@XZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall FlyCapture2::Camera::~Camera(void)" (__imp_??1Camera@FlyCapture2@@UAE@XZ) referenced in function "public: __thiscall ofxFlea3::ofxFlea3(void)" (??0ofxFlea3@@QAE@XZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall FlyCapture2::Error::~Error(void)" (__imp_??1Error@FlyCapture2@@UAE@XZ) referenced in function "void __cdecl PrintError(class FlyCapture2::Error)" (?PrintError@@YAXVError@FlyCapture2@@@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual void __thiscall FlyCapture2::Error::PrintErrorTrace(void)const " (__imp_?PrintErrorTrace@Error@FlyCapture2@@UBEXXZ) referenced in function "void __cdecl PrintError(class FlyCapture2::Error)" (?PrintError@@YAXVError@FlyCapture2@@@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual class FlyCapture2::Error __thiscall FlyCapture2::BusManager::GetCameraFromIndex(unsigned int,class FlyCapture2::PGRGuid *)" (__imp_?GetCameraFromIndex@BusManager@FlyCapture2@@UAE?AVError@2@IPAVPGRGuid@2@@Z) referenced in function "public: void __thiscall ofxFlea3::listDevices(void)" (?listDevices@ofxFlea3@@QAEXXZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall FlyCapture2::BusManager::~BusManager(void)" (__imp_??1BusManager@FlyCapture2@@UAE@XZ) referenced in function "public: void __thiscall ofxFlea3::listDevices(void)" (?listDevices@ofxFlea3@@QAEXXZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall FlyCapture2::Error::Error(class FlyCapture2::Error const &)" (__imp_??0Error@FlyCapture2@@QAE@ABV01@@Z) referenced in function "public: void __thiscall ofxFlea3::listDevices(void)" (?listDevices@ofxFlea3@@QAEXXZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual class FlyCapture2::Error __thiscall FlyCapture2::BusManager::GetNumOfCameras(unsigned int *)" (__imp_?GetNumOfCameras@BusManager@FlyCapture2@@UAE?AVError@2@PAI@Z) referenced in function "public: void __thiscall ofxFlea3::listDevices(void)" (?listDevices@ofxFlea3@@QAEXXZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall FlyCapture2::Error::Error(void)" (__imp_??0Error@FlyCapture2@@QAE@XZ) referenced in function "public: void __thiscall ofxFlea3::listDevices(void)" (?listDevices@ofxFlea3@@QAEXXZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall FlyCapture2::BusManager::BusManager(void)" (__imp_??0BusManager@FlyCapture2@@QAE@XZ) referenced in function "public: void __thiscall ofxFlea3::listDevices(void)" (?listDevices@ofxFlea3@@QAEXXZ)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual class FlyCapture2::Error __thiscall FlyCapture2::Image::Save(char const *,enum FlyCapture2::ImageFileFormat)" (__imp_?Save@Image@FlyCapture2@@UAE?AVError@2@PBDW4ImageFileFormat@2@@Z) referenced in function "public: void __thiscall ofxFlea3::initFlea3(int,int,int,int)" (?initFlea3@ofxFlea3@@QAEXHHHH@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual class FlyCapture2::Error __thiscall FlyCapture2::Image::Convert(enum FlyCapture2::PixelFormat,class FlyCapture2::Image *)const " (__imp_?Convert@Image@FlyCapture2@@UBE?AVError@2@W4PixelFormat@2@PAV12@@Z) referenced in function "public: void __thiscall ofxFlea3::initFlea3(int,int,int,int)" (?initFlea3@ofxFlea3@@QAEXHHHH@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual class FlyCapture2::Error __thiscall FlyCapture2::Image::ReleaseBuffer(void)" (__imp_?ReleaseBuffer@Image@FlyCapture2@@UAE?AVError@2@XZ) referenced in function "protected: virtual void __thiscall ofxFlea3::getNewFrame(unsigned char *)" (?getNewFrame@ofxFlea3@@MAEXPAE@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual struct FlyCapture2::TimeStamp __thiscall FlyCapture2::Image::GetTimeStamp(void)const " (__imp_?GetTimeStamp@Image@FlyCapture2@@UBE?AUTimeStamp@2@XZ) referenced in function "protected: virtual void __thiscall ofxFlea3::getNewFrame(unsigned char *)" (?getNewFrame@ofxFlea3@@MAEXPAE@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual unsigned char * __thiscall FlyCapture2::Image::GetData(void)" (__imp_?GetData@Image@FlyCapture2@@UAEPAEXZ) referenced in function "protected: virtual void __thiscall ofxFlea3::getNewFrame(unsigned char *)" (?getNewFrame@ofxFlea3@@MAEXPAE@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual unsigned int __thiscall FlyCapture2::Image::GetDataSize(void)const " (__imp_?GetDataSize@Image@FlyCapture2@@UBEIXZ) referenced in function "protected: virtual void __thiscall ofxFlea3::getNewFrame(unsigned char *)" (?getNewFrame@ofxFlea3@@MAEXPAE@Z)
1>ofxFlea3.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual void __thiscall FlyCapture2::Image::GetDimensions(unsigned int *,unsigned int *,unsigned int *,enum FlyCapture2::PixelFormat *,enum FlyCapture2::BayerTileFormat *)const " (__imp_?GetDimensions@Image@FlyCapture2@@UBEXPAI00PAW4PixelFormat@2@PAW4BayerTileFormat@2@@Z) referenced in function "protected: virtual void __thiscall ofxFlea3::getNewFrame(unsigned char *)" (?getNewFrame@ofxFlea3@@MAEXPAE@Z)

Answer 1

默认情况下，Visual Studio将对成员函数使用__thiscall。由于编译正确，库中的头文件似乎没有显式声明调用约定。

听起来你需要对这个库使用C语言的链接。尝试使用以下命令包装库头

extern "C" { }

Answer 2

问题是我链接的是64位版本的外部FlyCapture2库。切换到32位版本解决了这个问题。