following minimal reproduce fails with gcc 4.0.1:

template<typename T>
class TVector
{
public:
	T x,y,z,w;
};


template<typename T>
class TQuaternion : public TVector<T>
{
public:
	T Sum()
	{
		return x+y+z+w;
	}
};

the output produced is:

g++ -rdynamic -c -o test.o test.cpp
test.cpp: In member function 'T TQuaternion<T>::Sum()':
test.cpp:15: error: 'x' was not declared in this scope
test.cpp:15: error: 'y' was not declared in this scope
test.cpp:15: error: 'z' was not declared in this scope
test.cpp:15: error: 'w' was not declared in this scope

this should better work. it does e.g. in msvc.

i'm aware of e.g.
http://developer.apple.com/documentation/DeveloperTools/gcc-4.0.0/gcc/Name-lookup.html

requirements as mentioned in the document above clutter the code tremendously.
the complete code that this reproduce bases on also includes complex matrix
operation code, imagine how it looks after its made valid.

i'd be happy if someone could rethink the decisions on this.