从有符号问题到无符号问题的类型转换

我有一个如下函数：

template<typename T>
void myF(void* a, T* b, T c) 
{
    make_unsigned<T>::type newC;
    make_unsigned<T>::type* newB = ptr_cast<make_unsigned<T>::type*>(b);
    ...
}
template <typename T> T ptr_cast(void* ptr)
{
    return static_cast<T>(ptr);
}

这是使用type_traits类。它在VS 2010中工作得很好，但是当我使用ARM编译器编译时它会失败。编译器为 v. 5.02：http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.subset.swdev.ds5/index.html

我得到：找不到文件type_traits...我以为它在这一点上是标准库的一部分？

我尝试了make_unsigned的自定义实现：

namespace internal {
    #define MK_MAKEUNSIGNED(T,V)             
    template<> struct make_unsigned<T> {     
      public:                              
        typedef V type;                    
    };
    template<typename T>
    struct make_unsigned {
        typedef T type;
    };
    MK_MAKEUNSIGNED(sdata8, data8);
    MK_MAKEUNSIGNED(sdata16, data16);
    MK_MAKEUNSIGNED(sdata32, data32);
    MK_MAKEUNSIGNED(sdata64, data64);
    #undef MK_MAKEUNSIGNED
};

并修改为：

template<typename T>
void myF(void* a, T* b, T c) 
{
    internal::make_unsigned<T>::type newC;
    internal::make_unsigned<T>::type* newB = ptr_cast<internal::make_unsigned<T>::type*>(b);
    ...
}

同样，它在VS 2010中工作，但ARM编译器给出以下错误：

internal::make_unsigned<T>::type newC; #276 name followed by "::" must be a class or namespace name
^  
internal::make_unsigned<T>::type newC; #282 the global scope has no "type"
                            ^ 
internal::make_unsigned<T>::type newC; #65: expected a ';'
                                 ^
internal::make_unsigned<T>::type* newB = static_ptr<internal::make_unsigned<T>::type*>(b); #276 name followed by "::" must be a class or namespace name
^
internal::make_unsigned<T>::type* newB = static_ptr<internal::make_unsigned<T>::type*>(b); #282 the global scope has no "type" 
                            ^
internal::make_unsigned<T>::type* newB = static_ptr<internal::make_unsigned<T>::type*>(b); #20 identifier 'newB' nis undefined
                                  ^
internal::make_unsigned<T>::type* newB = static_ptr<internal::make_unsigned<T>::type*>(b); #276 name followed by "::" must be a class or namespace name
                                                    ^
internal::make_unsigned<T>::type* newB = static_ptr<internal::make_unsigned<T>::type*>(b); #276 name followed by "::" must be a class or namespace name
                                         ^
internal::make_unsigned<T>::type* newB = static_ptr<internal::make_unsigned<T>::type*>(b); #29 expected an expression                                                          
                                                                                     ^

所以我似乎无法使用type_traits或自定义实现来编译它。任何想法都非常感谢！