Returning a struct pointer from class method

Question

EDIT: Changed example code to code from my project that doesn't work.

I'm writing code in C++, learning templates and got stuck with some problem. There's a class:

template<class T, class Cmp>
class AVLtree {
public:
    AVLtree(const Cmp& _cmp) : root(nullptr), cmp(_cmp) {}
    AVLtree(const AVLtree& ref);
    ~AVLtree();

    AVLtree& operator = (const AVLtree& ref);

    void Add(const T& key);
    void TraverseDfs(void (*visit)(const T& key));
private:
    struct Node {
        Node* left;
        Node* right;
        T key;
        int balance;
        unsigned int height;
        unsigned int inheritence;

        Node(const T& _key) : left(nullptr), right(nullptr), key(_key), balance(0), height(1), inheritence(1) {}
    };
    Node* root;
    Cmp cmp;

    void deleteTree(Node* root);
    void traverse(Node* node, void(*visit) (const T& key));
    Node* addNode(Node* node, const T& key);
    Node* removeNode(Node* p, T key);
    int bfactor(Node* node);
    unsigned int height(Node* node);
    void fixheight(Node* node);
    Node* rotateRight(Node* p);
    Node* rotateLeft(Node* q);
    Node* balance(Node* p);
    Node* findmin(Node* p);
    Node* removemin(Node* p);
};

I want to define method addNode(Node* node, const T& key) out of class and here's what I write:

template<class T, class Cmp>
AVLtree<T, Cmp>::Node* AVLtree<T, Cmp>::addNode(Node* node, const T& key) {
    return new Node(key);
    if (!node) {
        return new Node(key);
    }
    if (cmp(key, node->key)) {
        node->left = addNode(node->left, key);
    }
    else {
        node->right = addNode(node->right, key);
    }
}

Then I try to run program and get such errors and warnings:

warning C4346: 'Node': dependent name is not a type

message : prefix with 'typename' to indicate a type

error C2061: syntax error: identifier 'Node'

error C2143: syntax error: missing ';' before '{'

error C2447: '{': missing function header (old-style formal list?)

It seems that I'm doing something wrong because, if I define method addNode(Node* node, const T& key) inside class, it works fine:

template<class T, class Cmp>
class AVLtree {
public:
   ...
private:
   ...
   Node* addNode(Node* node, const T& key) {
        return new Node(key);
        if (!node) {
            return new Node(key);
        }
        if (cmp(key, node->key)) {
            node->left = addNode(node->left, key);
        }
        else {
            node->right = addNode(node->right, key);
        }
     }
};

Any guesses what might be wrong?

Answer 1

Thanks for answers. Got a solution:

Just added typename before method definition outside of class. It looks like this:

template<class T, class Cmp>
typename AVLtree<T, Cmp>::Node* AVLtree<T, Cmp>::addNode(Node* node, const T& key) {
   ... 
}

It seems that this is some spicialization of Visual Studio because I can see that other compilers work fine with such code without any errors.