Speaking for C language, I've just found ampirically that following declaration code will be the solution;
typedef struct ListNode
{
int data;
ListNode * prev;
ListNode * next;
} ListNode;
So as a general rule, I give the same name both for both type definition and name of the struct;
typedef struct X
{
// code for additional types here
X* prev; // reference to pointer
X* next; // reference to pointer
} X;
Where following declarations are considered both incomplete by the gcc compiler when executing following statement. ;
removed->next->prev = removed->prev;
And I get same error for the dereferencing code reported in the error output;
>gcc Main.c LinkedList.c -o Main.exe -w
LinkedList.c: In function 'removeFromList':
LinkedList.c:166:18: error: dereferencing pointer to incomplete type 'struct ListNode'
removed->next->prev = removed->prev;
For both of the header file declarations listed below;
typedef struct
{
int data;
ListNode * prev;
ListNode * next;
} ListNode;
Plus this one;
typedef struct ListNodeType
{
int data;
ListNode * prev;
ListNode * next;
} ListNode;