我找不出这段代码为什么会出现错误。 引发错误的行在行尾注释。 错误信息如下所示。

我正在尝试实现一个简单的二进制搜索树BST，它有一个基类Tree。 这些类利用node类，它表示树中的单个节点。

template <typename Value>
class Node {
   private:
    Value value = 0;
    Node<Value>* leftChild = NULL;
    Node<Value>* rightChild = NULL;

   public:
    Node(Value value) { this->value = value; }
    ~Node() {
        delete leftChild;
        delete rightChild;
    }

    Value GetValue() const { return value; }

    void SetValue(Value value) { value = value; }

    Node<Value>* GetLeftChild() const { return leftChild; }

    void SetLeftChild(Node<Value>* leftChild) { leftChild = leftChild; }

    Node<Value>* GetRightChild() const { return rightChild; }

    void SetRightChild(Node<Value>* rightChild) { rightChild = rightChild; }
};
template <typename Value>
class Tree {
   protected:
    Node<Value>* root = NULL;
};
template <typename Value>
class BST : public Tree<Value> {
   private:
    // In main, I call bst._insertIntoSubtree(tree->root, newNode)
    Node<Value>* _insertIntoSubtree(Node<Value>* root, Node<Value>* newNode) {
        if (root) {
            if (root->GetValue() < newNode->GetValue()) {
                root->SetRightChild(_insertIntoSubtree(root->GetRightChild(), newNode->GetValue())); // Error
            } else {
                root->SetLeftChild(_insertIntoSubtree(root->GetLeftChild(), newNode->GetValue())); // Error
            }
            return root;
        } else {
            return newNode;
        }
    }
}

完整错误消息:

In file included from main.cpp:6:
Tree.hpp: In instantiation of 'Node<Value>* BST<Value>::_insertIntoSubtree(Node<Value>*, Node<Value>*) [with Value = int]':
Tree.hpp:128:9:   required from 'void BST<Value>::insert(Value) [with Value = int]'
Tree.hpp:122:13:   required from 'BST<Value>::BST(std::vector<_Tp>) [with Value = int]'
main.cpp:17:38:   required from here
Tree.hpp:108:17: error: invalid conversion from 'int' to 'Node<int>*' [-fpermissive]
                 root->SetRightChild(_insertIntoSubtree(root->GetRightChild(), newNode->GetValue()));
                 ^~~~
Tree.hpp:105:69: note:   initializing argument 2 of 'Node<Value>* BST<Value>::_insertIntoSubtree(Node<Value>*, Node<Value>*) [with Value = int]'
     Node<Value>* _insertIntoSubtree(Node<Value>* root, Node<Value>* newNode) {
                                                        ~~~~~~~~~~~~~^~~~~~~
Tree.hpp:110:17: error: invalid conversion from 'int' to 'Node<int>*' [-fpermissive]
                 root->SetLeftChild(
                 ^~~~
Tree.hpp:105:69: note:   initializing argument 2 of 'Node<Value>* BST<Value>::_insertIntoSubtree(Node<Value>*, Node<Value>*) [with Value = int]'
     Node<Value>* _insertIntoSubtree(Node<Value>* root, Node<Value>* newNode) {