Is it g++ bug with "typename"?

[Grizlyk]

Hello.

I am thinking: why if i will comment lines marked with '#' in the following
example, all will be compiled, else will not:


// ***********************
typedef unsigned uint;

namespace Pxx{
template <
          class Tobj,
          class c_Second,
          class Tuint=uint
         >
class First
{
public:
    typedef c_Second                  Second;
    typedef typename c_Second::Third  Third; //#1
    typedef typename c_Second::Forth  Forth; //#2

    First(){}
    inline explicit First(const Tuint);

public:
    class Tfriend
     {
      public:

      public:
        mutable First  *parent;

        void
        operator= (const First *const p)const
         { parent=const_cast<First*>(p); }

        Tfriend():parent(0){}
        Tfriend(const First& p):
            parent(const_cast<First*>(&p))
         {}
     };

};}

// ***********************
namespace Pxx{
template <
          class Tobj,
          class c_First,
          class c_Forth,
          class c_Third,
          class Tuint=uint
         >
class Second
{
public:
    typedef c_First    First;
    typedef c_Forth    Forth;
    typedef c_Third    Third;

    //derived Second
    typedef typename c_First::Second c_Second;

    Second(){}
    inline Second(const First&);
};}


// ***********************
// ***********************
namespace Pxx{
namespace Puser{

// ***********************
template <class Tobj,class Tuint> class First;
template <class Tobj,class Tuint> class Second;
template <class Tobj,class Tuint> class Third;
template <class Tobj,class Tuint> class Forth;

// ***********************
template <
          class Tobj,
          class Tuint=uint
         >
class First:
    public Pxx::First<
                        Tobj,
                        Second<Tobj,Tuint>,
                        Tuint
                       >
{
    typedef Pxx::First<
                        Tobj,
                        Second<Tobj,Tuint>,
                        Tuint
                       >
            Tparent;
public:
    typedef typename Tparent::Second  Second;

    First(){}
    explicit First(const Tuint p):Tparent(p){}
};

// ***********************
template <
          class Tobj,
          class Tuint=uint
         >
class Second:
    public Pxx::Second<
                            Tobj,
                            First<Tobj,Tuint>,
                            Forth<Tobj,Tuint>,
                            Third<Tobj,Tuint>,
                            Tuint
                           >
{
    typedef Pxx::Second<
                            Tobj,
                            First<Tobj,Tuint>,
                            Forth<Tobj,Tuint>,
                            Third<Tobj,Tuint>,
                            Tuint
                           >
            Tparent;

public:
    typedef typename Tparent::First  First;

    Second(){}
    Second(const First& p):Tparent(p){}
};


//namespace Puser
}
//namespace Pxx
}
using Pxx::Puser::First;
using Pxx::Puser::Second;


// ***********************
// ***********************
First<int> first(100);
Second<int> second(first);

=============
Output

11.cpp: In instantiation of
    'Pxx::Second<int,
    Pxx::Puser::First<int, unsigned int>,
    Pxx::Puser::Forth<int, unsigned int>,
    Pxx::Puser::Third<int, unsigned int>,
    unsigned int>':
11.cpp:113:   instantiated from
    'Pxx::Puser::Second<int, unsigned int>'
11.cpp:14:   instantiated from
    'Pxx::First<int,
    Pxx::Puser::Second<int, unsigned int>,
    unsigned int>'
11.cpp:86:   instantiated from
    'Pxx::Puser::First<int, unsigned int>'
11.cpp:141:   instantiated from here
11.cpp:57: error: no type named 'Second' in 'class
11.cpp:57: error: Pxx::Puser::First<int, unsigned int>'


-- 
Maksim A. Polyanin
http://grizlyk1.narod.ru/cpp_new