c++ fatal error C1061，带有大开关，元编程

Question

这是代码:

static inline void 
shrinkData(const vector<Data> &data, unsigned short shrinkType){
    #define CASE_N(N) \
    case(N): \
        ptr = MemoryManager::requestMemory(n*sizeof(ShrinkData<N>)); \
        for(int i=0; i<n; i++){ \
            new(ptr) ShrinkData<N>(data[i]); \
            ptr+=sizeof(ShrinkData<N>); \
        } \
        return;


    int n = data.size();
    char* ptr;

    switch(shrinkType){
    case(0):
        return;
    CASE_N(1)
    CASE_N(2)
    CASE_N(3)
    ....
    CASE_N(255)
}

现在我在 CASE_N(124) 行收到致命的“错误 C1061:编译器限制: block 嵌套太深”

谁能告诉我为什么会这样？实际上嵌套不应该超过 2，不是吗？

谢谢!

//编辑:请求的构造函数(构造函数在没有这个开关函数的情况下工作得很好)

enum {//maximally 16 to fit in a unsigned short!
    EID_POSITION        =   1, //bit1
    EID_T               =   2, //bit2
    EID_GEOMNORMAL      =   4, //bit3
    EID_NORMAL          =   8, //bit4
    EID_TANGENTS        =  16, //bit5
    EID_TEXCOORDS       =  32, //bit6
    EID_RAYDIR          =  64, //bit7
    EID_RECURSIONDEPTH  = 128  //bit8
};



template<unsigned, unsigned>
struct IDataMember{
    IDataMember(){}
    IDataMember(const Data &iData){}
};


template<>
struct IDataMember<EID_POSITION, EID_POSITION>{
    IDataMember(): position(Vector3(0,0,0)){}
    IDataMember(const Data &iData):position(iData.position){}
    Vector3 position;
};

...枚举中每种类型的相同类型的模板特化...

template<unsigned members>
struct ShrinkData
    :public IDataMember<members & EID_POSITION, EID_POSITION>
    ,public IDataMember<members & EID_T, EID_T>
    ,public IDataMember<members & EID_GEOMNORMAL, EID_GEOMNORMAL>
    ,public IDataMember<members & EID_NORMAL, EID_NORMAL>
    ,public IDataMember<members & EID_TANGENTS, EID_TANGENTS>
    ,public IDataMember<members & EID_TEXCOORDS, EID_TEXCOORDS>
    ,public IDataMember<members & EID_RAYDIR, EID_RAYDIR>
    ,public IDataMember<members & EID_RECURSIONDEPTH, EID_RECURSIONDEPTH>
{
    ShrinkData()
        :IDataMember<members & EID_POSITION, EID_POSITION>()
        ,IDataMember<members & EID_T, EID_T>()
        ,IDataMember<members & EID_GEOMNORMAL, EID_GEOMNORMAL>()
        ,IDataMember<members & EID_NORMAL, EID_NORMAL>()
        ,IDataMember<members & EID_TANGENTS, EID_TANGENTS>()
        ,IDataMember<members & EID_TEXCOORDS, EID_TEXCOORDS>()
        ,IDataMember<members & EID_RAYDIR, EID_RAYDIR>()
        ,IDataMember<members & EID_RECURSIONDEPTH, EID_RECURSIONDEPTH>(){}


    ShrinkData(const Data &iData)
        :IDataMember<members & EID_POSITION, EID_POSITION>(iData)
        ,IDataMember<members & EID_T, EID_T>(iData)
        ,IDataMember<members & EID_GEOMNORMAL, EID_GEOMNORMAL>(iData)
        ,IDataMember<members & EID_NORMAL, EID_NORMAL>(iData)
        ,IDataMember<members & EID_TANGENTS, EID_TANGENTS>(iData)
        ,IDataMember<members & EID_TEXCOORDS, EID_TEXCOORDS>(iData)
        ,IDataMember<members & EID_RAYDIR, EID_RAYDIR>(iData)
        ,IDataMember<members & EID_RECURSIONDEPTH, EID_RECURSIONDEPTH>(iData){}

};

Answer 1

根据这个link编译器中有一个“功能”只允许有限数量的循环。从来没有发生在我身上。尝试将 ptr 初始化和以下 for 循环放在一个 block 中。另一种解决方案是创建覆盖整个代码段的模板函数，这样宏就变成了这样:

#define CASE_N(N) \
case(N): \
    ptr = requestAndInitialize<N>(data); \
    return;