与std :: map一起使用的枚举值导致错误C2664

Question

我想了解为什么代码

enum
{
   SETA_ELT1,
   SETA_ELT2,
   SETA_ELT3,
};

enum
{
   SETB_ELT1,
   SETB_ELT2,
   SETB_ELT3,
};

#define MAPPINGTYPE std::map<unsigned int, unsigned int> 
MAPPINGTYPE::value_type bijection_table[] = //<---- line 68 raising the error
{
   MAPPINGTYPE::value_type(SETA_ELT1, SETB_ELT1),
   MAPPINGTYPE::value_type(SETA_ELT2, SETB_ELT2),
   MAPPINGTYPE::value_type(SETA_ELT3, SETB_ELT3),
};

const MAPPINGTYPE bijectionMap(bijection_table, bijection_table+3);

无法在Visual Studio 10上编译错误

2>c:\Program Files (x86)\${MVCDIR}\VC\include\utility(246): 
2>error C2664: 'std::forward' : cannot convert parameter 1 from '' to '&'
2>          ..\myfile.cpp(68) : see reference to function template instantiation 
2>'std::pair<_Ty1,_Ty2>::pair<,>(_Other1 &&,_Other2 &&)' being compiled
2>          with
2>          [
2>              _Ty1=const unsigned int,
2>              _Ty2=unsigned int,
2>              _Other1=,
2>              _Other2=
2>          ]

我需要显式地将值SETB_ELTX强制转换为unsigned int才能成功编译。