Error: Dereferencing pointer to incomplete type (?)

[tom66]

I am getting errors with GCC trying to compile this:



void way_update_bbox(struct Way *way, struct Node *node)
{
/* Updates the bbox of the way. Doesn't reevaluate all the nodes;
* instead, it checks to see if the passed node is outside of the
* current way's bbox. */
if(!bbox_in_test(&way->bbox, node->pos)) {
// Is the point outside of the top left of the rectangle?
if(way->bbox.tl.lat > node->pos.lat || way->bbox.tl.lon > node->pos.lon) {
way->bbox.tl.lat = node->pos.lat;
way->bbox.tl.lon = node->pos.lon;
return;
}
// Is the point outside of the bottom right of the rectangle?
if(way->bbox.br.lat < node->pos.lat || way->bbox.br.lon < node->pos.lon) {
way->bbox.br.lat = node->pos.lat;
way->bbox.br.lon = node->pos.lon;
return;
}
}
}


with the definitions for position.h here:



#pragma once
#define DIV_DOUBLE(a, b) ((double)(a) / (double)(b))
#define DEG_2_RAD(x) (x * 0.0174532925)

struct Position2D
{
// Latitude & longitude stored as unsigned values 0 - 2^32-1.
// This is accurate to seven and a half decimal places when
// translated into lat/lon.
unsigned int lat, lon;
};

struct Position2DBBox
{
// Bounding box with top left and bottom left positions.
struct Position2D tl;
struct Position2D br;
};

void position_to_lat_lon(struct Position2D *, double *, double *);
void lat_lon_to_position(struct Position2D *, double, double);
double position_distance(struct Position2D *, struct Position2D *);
int position_quick_distance(struct Position2D *, struct Position2D *);
double position_accurate_distance(struct Position2D *, struct Position2D *);

int bbox_in_test(struct Position2DBBox *, struct Position2D *);


and for node.h:



#pragma once
#include "position.h"
#include "way.h"
#include "tags.h"

struct MapNode
{
int numWays;
struct MapWay **ways; // Ways this node belongs to.
struct Position2D pos; // Lat, Lon position.
struct Tag *head_tag;
};


and for way.h:



#pragma once
#include "node.h"
#include "tags.h"

struct Node;

struct Way
{
int numNodes;
struct Node **nodes;
struct Tag *head_tag;
struct Position2DBBox bbox;
};

void way_add_node(struct Way *way, struct Node *node);


The errors are:



In file included from test.c:3:
node.c: In function ‘node_find_new’:
node.c:29: warning: unused variable ‘n’
node.c:29: warning: unused variable ‘i’
node.c:28: warning: unused variable ‘node’
In file included from test.c:4:
way.c: In function ‘way_update_bbox’:
way.c:19: error: dereferencing pointer to incomplete type
way.c:21: error: dereferencing pointer to incomplete type
way.c:21: error: dereferencing pointer to incomplete type
way.c:22: error: dereferencing pointer to incomplete type
way.c:23: error: dereferencing pointer to incomplete type
way.c:27: error: dereferencing pointer to incomplete type
way.c:27: error: dereferencing pointer to incomplete type
way.c:28: error: dereferencing pointer to incomplete type
way.c:29: error: dereferencing pointer to incomplete type


I don't know what I am doing wrong. I suspect it may have something to do with forward declarations of structures, but I wouldn't know how to fix it.

[tom66]

Never mind, I just fixed my problem! Turns out that I had forward declared 'Node' instead of 'MapNode'; the compiler didn't know anything about 'MapNode' and kept trying to reference 'Node'.