Question

Okay, so this is really werid. I’ve never encountered anything like this.

Part of my program (Fails to compile) contains three namespaces as following:

// namespaceA.h
namespace A {
enum Kind { jimmy, david };
}
// end of namespaceA.h

// namespaceB.h
#include "namespaceA.h"
namespace B {
class Tree {
    public:
    Tree *prev;
    Tree *next;
    Tree *down;
    A::Kind kind;

    Tree();
    ~Tree();
};
}
// end of namespaceB.h
// Implementation details of the class are placed in namespaceB.cc
// Constructor / Desctructor defined in the namespaceB.cc file!
// Something like this,
#include "namespaceB.h"
namespace B {
inline Tree::Tree() { ... }
inline Tree::~Tree() { ... }
}

// namespaceC.cc
#include "namespace.B"
namespace C {
void run() {
    B::Tree *tree;    // FINE
    B::Tree tree;     // Fail to compile!?
}
}
// end of namespaceC.cc

Now, g++ went along just fine but the linker ld complains:

 "namespaceC.cc: undefined reference to `B::Tree::Tree()'
 "namespaceC.cc: undefined reference to `B::Tree::~Tree()'

I have never ever encountered anything like this before… This just seems really weird, I don’t even know any words/terms to describe this problem.

I would much appreciate any help.

Thanks,

Answer 1

Your definitions of B::Tree::Tree() and B::Tree::~Tree() are declared inline. This means they are only available in that source file, not any others.

Either removing inline from the definitions, or moving the inline definitions into a header file included by all source files that need them, should fix the link errors.