The compiler is reporting "no match" for an friend operator==() which happens to be correctly defined.
The class for which the operator is defined is a specialization of a class template.
This inability to find the right operator only occurs, to my knowledge, when the operator is defined
as a friend function inside a template class specialization.
The error also goes away with one very simple yet apparently meaningless change, which in my example
code can be enabled with '-DTEST'.

[bgreen@pc125 tmp]$ g++ -c mytest2.C
mytest2.C: In function `bool operator== (const cell &, const cell &)':
mytest2.C:35: no match for `const myval<int> & == const myval<int> &'
mytest2.C:34: candidates are: bool operator== (const cell &, const cell &)
[bgreen@pc125 tmp]$
[bgreen@pc125 tmp]$ g++ -DTEST -c mytest2.C
[bgreen@pc125 tmp]$

Release:
gcc version 2.97 20001112 (experimental)

Environment:
uname -a:
Linux pc125.nas.nasa.gov 2.2.16-22smp #1 SMP Tue Aug 22 16:39:21 EDT 2000 i686 unknown

How-To-Repeat:
template <class T>
class myval
{
  T d;

public:
  myval(const myval &v) : d(v.d) {}
  friend bool operator==(const myval<T>& lhs, const myval<T>& rhs) {
    return lhs.d == rhs.d;
  }
};

template<>
class myval<int>
{
  int d;

public:
  myval(const myval &v) : d(v.d) {}
  friend bool operator==(const myval<int>& lhs, const myval<int>& rhs) {
    return lhs.d == rhs.d;
  }
};


class cell {
  myval<int> v;

public:
#ifdef TEST
  cell(const myval<int> &in) : v(in) {}
#endif
  friend bool operator==(const cell& lhs, const cell& rhs) {
    return lhs.v == rhs.v;
  }
};