Re: pointer casts

[Owen Taylor <otaylor redhat com>]

Miroslaw Dobrzanski-Neumann <mne mosaic-ag com> writes:

> Hi,
> 
> Compiling gclosure.c with DEC C V5.6-082 compiler I get the warnings listed
> below (the same warnings are produced by the ibm xlc compiler). The problem is
> that pointer to void is not the same as pointer to function. You can safe cast
> data pointer but casting function pointer in i.e. pascal calling convention and
> calling it afterwards as different ones produce a desaster.
> 
> After having take a look at the data types of the two sides of the assignemt I
> wonder how it works.
> 
> gclosure.c:107 closure->marshal = (gpointer) ndata->notify;

GCC has a non-standard extension that allows implicit casts betweeen (void *)
and any function pointers.

Unfortunately, this has led to people doing bad stuff like this and also to
some messed up prototypes like:

gulong	 g_signal_handler_find		      (gpointer		  instance,
					       GSignalMatchType	  mask,
					       guint		  signal_id,
					       GQuark		  detail,
					       GClosure		 *closure,
					       gpointer		  func,
					       gpointer		  data);

That we just have to live with at this point.

I've given Erwann the go ahead to commit his patch in #73898 which should fix
all of these sorts of warnings in GLib.

Regards,
                                        Owen