//define struct type
typedef struct Lnode {

    int data;
    struct LNode* next;
    
}Lnode;

//creat Link list
void CreatList() {

    //creat Head pointer and Tail pointer
    Lnode** Head;
    Lnode* Tail;

    //creat an empyt Link list
    *Head = (Lnode* )malloc(sizeof(Lnode));
    (*Head)->next = NULL;
    
    Tail = *Head;

    //insert data 
    for (int i = 0; i < 3; ++i) {
        
        //creat new node
        Lnode* P = (Lnode* )malloc(sizeof(Lnode));
        
        //update date domain and pointer domain of new node
        P->data = i;
        P->next = NULL;

        //update pointer domain of before node
        Tail->next = P;

        //update Tail pointer Location
        Tail = P;

    }

}  

gcc 9.2.0 报错

.\Link.c: In function 'CreatList':
.\Link.c:45:20: warning: assignment to 'struct LNode *' from incompatible pointer type 'Lnode *' {aka 'struct Lnode *'} [-Wincompatible-pointer-types]
   45 |         Tail->next = P;
      |                    ^

我觉得没错啊 Tail->next 与 P 都是 Lnode* 类型啊

line5: struct LNode* next -> struct Lnode* next

额，Head是二级指针也是野指针吧，为什么可以把它指向的地址赋值呢？
*Head = (Lnode* )malloc(sizeof(Lnode));

//define struct type
typedef struct Lnode {

    int data;
    struct Lnode *next;
   
}Lnode;

typedef struct head{
    Lnode *Head;
    lnode *Tail;
}head;

//creat Link list
void CreatList() {

    //creat Head pointer and Tail pointer
    head h;
    h -> Head = NULL;
    h -> Tail = NULL;

    //insert data
    for (int i = 0; i < 3; ++i) {
        
        //creat new node
        Lnode* P = (Lnode* )malloc(sizeof(Lnode));
        
        //update date domain and pointer domain of new node
        P->data = i;
        P->next = NULL;

        //update pointer domain of before node
        h -> Tail->next = P;

        //update Tail pointer Location
        h -> Tail = P;

    }

}