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使用GCC 4.7.3,我得到以下错误为什么这个可变参数模板专门化定义不能编译?
prog.cpp: In function ‘int main()’: prog.cpp:27:63: error: ‘Erase >::Result’ has not been declared
template <typename... List>
struct TypeList
{
enum
{
Length = sizeof...(List)
};
};
template <typename ToErase, typename... List>
struct Erase;
template <typename ToErase>
struct Erase<ToErase, TypeList<>>
{
typedef TypeList<> Result;
};
template <typename ToErase, typename... Head, typename... Tail>
struct Erase<ToErase, TypeList<Head..., ToErase, Tail...>>
{
typedef TypeList<Head..., Tail...> Result;
};
int main()
{
static_assert(Erase<double, TypeList<int, double, char>>::Result::Length == 2,
"Did not erase double from TypeList<int, double, char>");
return 0;
}
我不明白为什么代码不会编译给我收到错误消息,因为一个类似的情况下编译干净:
是否有一个标准关于不能推断元素在tw中o参数包,就像我想要做的第一块代码?