Inheritance inside a template - public members become invisible?
- by Juliano
I'm trying to use inheritance among classes defined inside a class template (inner classes). However, the compiler (GCC) is refusing to give me access to public members in the base class.
Example code:
template <int D>
struct Space {
struct Plane {
Plane(Space& b);
virtual int& at(int y, int z) = 0;
Space& space; /* <= this member is public */
};
struct PlaneX: public Plane {
/* using Plane::space; */
PlaneX(Space& b, int x);
int& at(int y, int z);
const int cx;
};
int& at(int x, int y, int z);
};
template <int D>
int& Space<D>::PlaneX::at(int y, int z) {
return space.at(cx, y, z); /* <= but it fails here */
};
Space<4> sp4;
The compiler says:
file.cpp: In member function ‘int& Space::PlaneX::at(int, int)’:
file.cpp:21: error: ‘space’ was not declared in this scope
If using Plane::space; is added to the definition of class PlaneX, or if the base class member is accessed through the this pointer, or if class Space is changed to a non-template class, then the compiler is fine with it.
I don't know if this is either some obscure restriction of C++, or a bug in GCC (GCC versions 4.4.1 and 4.4.3 tested). Does anyone have an idea?
