Re: More 64bit issues (Was: Re: gtype.h broken for 64-bit)

[Tim Janik <timj gtk org>]

On 26 Nov 2001, Owen Taylor wrote:

> Tim Janik <timj gtk org> writes:
> 
> > hm, the first question that comes to mind here is:
> > why didn't gcc catch ("%u", (gsize) x) in the first place, i.e.
> > on x86?
> > the answer is, because we define gsize to guint32 if their sizes
> > match.
> > unfortunately, doing #define gsize gulong if sizeof(gsize)==sizeof(gulong)
> > introduces new problems, such as:
> >   #include <malloc.h>
> >   void (*my_malloc) (size_t size) = malloc;
> > warns about invalid pointer type assigment, because size_t is defined
> > to int in standard headers for x86 as well ;(
> > while i think that #define gsize gulong would have been the right
> > thing to do to deal with a type that changes sizes on 32/64 bit platforms,
> > it seems we can't do this here.
> > 
> > so, i'm now planning to have:
> > 
> > #if     GLIB_SIZEOF_LONG == GLIB_SIZEOF_SIZE_T
> > typedef gulong                          GType;
> > #else   /* hm, shouldn't happen? */
> > typedef gsize                           GType;
> > #endif
> > 
> > any better ideas?
> 
> Hmmm, shouldn't we just make gsize a gulong when the size matches?
> After all, size_t is long on most systems.

hm, i adressed that above. on 32bit x86, the glibc
headers do (or _can_ do):
	# define size_t          unsigned int
	void *malloc(size_t size);
if glib then does
	#define gsize gulong
you actually get a pointer mismatch with
	void* (*foo) (gsize) = malloc;
or
	gsize *x = (size_t*) pointer;
which is arguably quite irritating.

before we actually define gsize as gulong, i'd like to know why glibc does
	# define size_t          unsigned int
instead of
	# define size_t          unsigned long int
on systems where sizeof(long)==sizeof(int).
maybe that's for historic reasons, but it doesn't exactly help people
writing code on 32bit archs portably across 64bit archs.

ulrich, could you shed some light on this?

> Or is this too much of an API change? (In one sense, it isn't
> an API change at all, since it is already _possible_ that gsize
> is a long.)
> 
> Right now, to supress warnings, you would have to do something
> like:
> 
>  g_print ("Length of GString is %lu bytes\n", (gulong)string->len);
> 
> Which people won't even discover until they try and compile on
> a 64-bit system.

yeah, that's a vlid concern beyond just typedef gsize GType;

> 
> Regards,
>                                         Owen
> 

---
ciaoTJ