Strangest Error I Have Ever Seen, a.k.a. ) * - c

Question

I'm writing this awesome application, at least I think it awesome, in C with the magnificent blend of GObject and after a while I start getting this very, extremely strange error. I also believe to have noticed it not appearing always. However this might just be the IDE's fault. Anyhow...
GCC, apparently, complains: expected ')' before '*' token; this happens in a header file.
This is that very same header file.
#pragma once
#include "global.h"
#include "CharcoalApp.h"
GtkListStore *WebsitesListStore;
// that error is reported for this line
void charcoal_websites_list_initialize(CharcoalApp *app);
As far as I can see, this comes from the CharcoalApp *app parameter for that function.
Because I cannot really understand why this error is happening, I'll include the CharcoalApp.h file. global.h is a very simple header file that carries the main dependencies, mainly GLib, GObject, GThread, GTK+, WebKit and other.
CharcoalApp.h
#ifndef __CHARCOAL_APP_H__
#define __CHARCOAL_APP_H__
#include "global.h"
#include "CharcoalDB.h"
#include "CharcoalWindow.h"
#include "CharcoalWebsitesList.h"
G_BEGIN_DECLS
#define CHARCOAL_TYPE_APP (charcoal_app_get_type())
#define CHARCOAL_APP(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj), CHARCOAL_TYPE_APP, CharcoalApp))
#define CHARCOAL_APP_CONST(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj), CHARCOAL_TYPE_APP, CharcoalApp const))
#define CHARCOAL_APP_CLASS(klass) (G_TYPE_CHECK_CLASS_CAST((klass), CHARCOAL_TYPE_APP, CharcoalAppClass))
#define CHARCOAL_IS_APP(obj) (G_TYPE_CHECK_INSTANCE_TYPE((obj), CHARCOAL_TYPE_APP))
#define CHARCOAL_IS_APP_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass), CHARCOAL_TYPE_APP))
#define CHARCOAL_APP_GET_CLASS(obj) (G_TYPE_INSTANCE_GET_CLASS((obj), CHARCOAL_TYPE_APP, CharcoalAppClass))
typedef struct _CharcoalApp CharcoalApp;
typedef struct _CharcoalAppClass CharcoalAppClass;
typedef struct _CharcoalAppPrivate CharcoalAppPrivate;
struct _CharcoalApp {
GObject parent;
CharcoalAppPrivate *priv;
GtkBuilder *ui;
CharcoalDB *db;
// toplevels
GtkWidget *CharcoalWindow;
};
struct _CharcoalAppClass {
GObjectClass parent_class;
};
GType charcoal_app_get_type(void) G_GNUC_CONST;
CharcoalApp *charcoal_app_new(void);
void charcoal_app_quit(CharcoalApp *app);
G_END_DECLS
#endif /* __CHARCOAL_APP_H__ */
Thank you for your help!

Answer 1

CharcoalApp is not declared in global.h. Suppose you are including CharcoalApp.h in your C file:
CharcoalApp.h is read up to #include "global.h"
global.h is included
Error: expected ')' before '*' token
You should rearrange your header files properly or use a forward declaration (although I don't think is needed in this case).
There are many solutions:
the proper way: include CharcoalApp.h from global.h, not the reverse;
move typedef struct _CharcoalApp CharcoalApp; before `#include "global.h" in CharcoalApp.h;
remove #include "global.h" from CharcoalApp.h and include them in the proper order (global.h last).

Answer 2

I'm not sure if it's obvious to everyone, but I should add that the reason it's complaining (I think) is because it doesn't understand that CharcoalApp is a type name at the time that it's parsing that code (I've seen similar compile-time errors many times in the past). I think it is handling it as a parameter name instead of a parameter's type name, so it expects the end of the argument list (or a comma) instead of another parameter name without a comma.

Answer 3

How about:
#pragma once
#include "global.h"
//#include "CharcoalApp.h"
struct CharcoalApp;
GtkListStore *WebsitesListStore;
// that error is reported for this line
void charcoal_websites_list_initialize(CharcoalApp *app);
Its not exactly pretty, but removing header includes inside other headers and replacing them with forward declarations is something I was taught once and always try to do.
It reduces the amount of time I spend swearing at the compiler over cyclic dependancy significantly, and it also keeps build times down when changing a commonly included header file.
: D

Answer 4

Looks to me like GtkListStore is not defined.

Answer 5

Try changing your code to:
struct _CharcoalApp {
GObject parent;
CharcoalAppPrivate *priv;
GtkBuilder *ui;
CharcoalDB *db;
// toplevels
GtkWidget *CharcoalWindow;
};
struct _CharcoalAppClass {
GObjectClass parent_class;
};
typedef struct _CharcoalApp CharcoalApp;
typedef struct _CharcoalAppClass CharcoalAppClass;
typedef struct _CharcoalAppPrivate CharcoalAppPrivate;
When you uttered the typedef, the underlying structure type wasn't defined yet, and this MIGHT have confused something.
I normally just write something like:
typedef struct {
GObject parent;
CharcoalAppPrivate *priv;
GtkBuilder *ui;
CharcoalDB *db;
// toplevels
GtkWidget *CharcoalWindow;
} CharcoalApp;