#include <atomic>
 
template<typename T>
class List {
public:
  void append(const T& value);   // see below
 
private:
  struct Node { 
    T data;
    Node *next; 
  };  
 
  std::atomic<Node*> head;
};
 
template<typename T>
void List<T>::append(const T& value)
{
  Node *newNode = new Node { value };
 
  Node* headNode;
  do {
    headNode = head;
    newNode->next = head;
  } while (!std::atomic_compare_exchange_weak(&head, &headNode, newNode));
  // or while (!head.compare_exchange_weak(headNode, newNode));
}
 
int main()
{
  List<int> li;
  li.append(10);
}
 

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