vs2019出现未定义标识符错误

可有人识得此误↓

.c文件代码如下

int user_list_del(FRND_ST* fs, short cnt)
{
    CLIENT_FRND* cp;
    struct list_head* pos = NULL, * head = &myself.w_flisthd;
    for (int i = 0; i < cnt; i++)
    {
        list_for_each(pos,head);
        {
            cp = (CLIENT_FRND*)list_entry(pos, CLIENT_FRND, c_node);
            if (cp->c_id == fs[i].fs_id)
            {
                break;
            }
        }
        if (pos == head)
        {
            continue;
        }
        cp = (CLIENT_FRND*)list_entry(pos, CLIENT_FRND, c_node);
        list_del(&(cp->c_node));
        free(cp);
    }
    return 0;
}

.h文件代码如下

#define offsetof(t,m) ((size_t)(&((t *)0)->m))

#define container_of (ptr, type, member)\
    (char *)(ptr) - offsetof(type, member)

#define list_entry(ptr, type, member) \
    container_of(ptr, type, member)

#define container_of (ptr, type, member)
(char *)(ptr) - offsetof(type, member)
这里的ptr是什么东西？是变量吗？宏定义里不能这么用变量啊兄弟