c++ - g++ 4.7.2处理用于类型别名的方法似乎已损坏

在以下代码中，看来g++ 4.7.2被基于using的类型别名所混淆。

编码:

#include <map>

enum class Direction
{
  UP=-1,
  DOWN=1
};

template <Direction dir>
struct Comparator
{
  bool operator()(int lhs, int rhs) const
  {
    return lhs<rhs; // Comparison should be based on dir
                    // but let's not even use dir for now
  }
};

template <Direction dir>
using IntToIntMap=std::map<int, int, Comparator<dir>>;

template <Direction dir>
void TestFunc()
{
  using TheMap=IntToIntMap<dir>; // TheMap should be a synonym for
                                 // IntToIntMap<dir>

  typename IntToIntMap<dir>::value_type value1; // This compiles
  typename TheMap::value_type value2;           // This does not (???)
}

int main()
{
  TestFunc<Direction::UP>();
}

使用以下代码编译代码:

g++ -std=c++11 -Wall --pedantic -o test test.cpp

意外的编译时间错误:

test.cpp: In instantiation of 'void TestFunc() [with Direction dir =
                                                (Direction)-1]
test.cpp:34:29:   required from here
test.cpp:29:33: error: no type named 'value_type' in 'using TheMap =
                                      IntToIntMap<dir>'

所讨论的行有什么问题？代码是否违反了C++ 11标准，或者这是g++ 4.7.2错误？ Live code in g++-4.7

最佳答案

根据评论，它已在gcc-4.8中修复:

4.7:http://coliru.stacked-crooked.com/view?id=9d55db125baaac0b169e61bbcfcb2a26-f2a3752efd0426bdaa29babef505f76e

4.8:http://coliru.stacked-crooked.com/a/6cd0ad895d067e51