Error C2440: 'function' : cannot convert from 'node *' to 'node' - c

Question

I get this error when i try to run the program:
Error C2440: 'function' : cannot convert from 'node *' to 'node'
And i can't figure out what i'm doing wrong when i'm calling the method destroy_node with first_node as argument.
int dequeue(int *data)
{
node *first_node;
int result = 0;
if(queueref.first != NULL){
first_node = queueref.first;
data = (int*) queueref.first->data;
queueref.first = first_node->next;
result = destroy_node(first_node);
}
return result;
}
static int destroy_node(node *node_ref)
{
int data = 0;
free(node_ref);
if(node_ref == NULL){
data = 1;
}
return data;
}
Thanks for the help!
Edit:
The whole class and its this code that givs an error: result = destroy_node(first_node);
#include <stdlib.h>
#include <stdio.h>
typedef struct node {
int data;
struct node *next;
} node;
typedef struct {
struct node *first;
struct node *last;
} queue_c;
static queue_c queueref;
//Funktionsprototyper
#include "queue.h"
static int destroy_node(node node_ref);
static node *create_node(int data);
int enqueue(int data)
{
node *new_node, *last_node;
int result = 0;
new_node = create_node(data);
if(new_node != NULL){
if(queueref.first != NULL){
queueref.first = new_node;
queueref.last = new_node;
}
else{
queueref.last->next = new_node;
queueref.last = new_node;
}
result = 1;
}
return result;
}
static node *create_node(int data)
{
node *noderef;
noderef = (node*) malloc(sizeof(node));
noderef->data = data;
noderef->next = NULL;
return noderef;
}
int dequeue(int *data)
{
node *first_node;
int result = 0;
if(queueref.first != NULL){
first_node = queueref.first;
data = (int*) queueref.first->data;
queueref.first = first_node->next;
result = destroy_node(first_node);
}
return result;
}
static int destroy_node(node *node_ref)
{
free(node_ref);
return node_ref == NULL;
}
void print_queue()
{
node *curr_ptr = queueref.first;
if(curr_ptr != NULL){
while(curr_ptr != NULL){
printf("%d -> ", curr_ptr->data);
curr_ptr = curr_ptr->next;
}
}
else{
printf("Kön är tom!");
}
}
int delete_node(int data)
{
int result = 0;
node *curr_ptr;
node *prev_ptr;
node *temp_ptr;
if(queueref.first == NULL){
printf("Kön är tom!");
}
else if(queueref.first->data == data){
temp_ptr = queueref.first;
queueref.first = queueref.first->next;
result = destroy_node(temp_ptr);
}
else{
prev_ptr = queueref.first;
curr_ptr = queueref.first->next;
while(curr_ptr != NULL){
if(curr_ptr->data == data){
result = 1;
break;
}
prev_ptr = curr_ptr;
curr_ptr = curr_ptr->next;
}
if(result){
temp_ptr = curr_ptr;
prev_ptr->next = temp_ptr->next;
result = destroy_node(temp_ptr);
}
else{
printf("Ingen node innehöll talet: %d", data);
}
}
return result;
}
Edit:
Unwind where right i had forgotten to put a prototype in queue.h and i missed that when i went through the program.

Answer 1

There might be a conflicting prototype; the code as shown shouldn't generate this error. But it also should generate at least a warning since you're calling an unknown function; it would make more sense to put all of destroy_node() before the place where it's called, or add a prototype.
Note that the destroy_node() function is needlessly complex. It could be rewritten as:
static int destroy_node(node *node_ref)
{
free(node_ref);
return node_ref == NULL;
}