Problems with binary member and friend operator in template class

[Georg Hager <georg.hager@xxxxxxxxxxxxxxxxxxxx>]

Hi all,

g++ 4.0.3 reports an error when compiling the following C++
source. The problem appears when I declare a binary operator (here
operator+) once as a member and once as a friend with the class type
as second parameter:

----------------------------------------------
#include <iostream>
using namespace std;

template <class T> class P;

template <class T> P<T> operator+(T,const P<T>&);

template <class T>
class P{
private: 
  T d;
public:
  explicit P(int i=0);
  P<T> operator+(T);
  friend P<T> operator+<>(T,const P<T>&); // line 15
};

template <class T>
P<T>::P(int i) : d(i) {}

template <class T>
P<T> P<T>::operator+(T x)
{
  return P<T>(x*d);
}

template <class T> P<T> operator+(T x,const P<T>& p)
{
  return P<T>(x*p.d);
}

int main()
{
  P<int> p(4),q,r;
  q=3+p;
  r=p+3;
  return 0;
}

----------------------------------------------

The error is:

opp.cc:15: error: declaration of 'operator+' as non-function
opp.cc:15: error: expected ';' before '<' token
opp.cc: In function 'P<T> operator+(T, const P<T>&) [with T = int]':
opp.cc:35:   instantiated from here
opp.cc:11: error: 'int P<int>::d' is private
opp.cc:29: error: within this context

This might be my misunderstanding the C++ standard, but I
strongly suspect it's a compiler bug. I have to add the following
observations:

- the code compiles if, everything else being equal, 
  the class is not a template
- the code compiles if the member operator* and the 
  friend declarations are interchanged

Thanks for any help,
Georg.