Re: AC_COMPUTE_INT's arguments

[Ralf Wildenhues]

Hello Stepan,

* Stepan Kasal wrote on Mon, Sep 04, 2006 at 06:30:19PM CEST:
> On Sun, Sep 03, 2006 at 10:00:08AM +0200, Ralf Wildenhues wrote:
> > * Stepan Kasal wrote on Sat, Sep 02, 2006 at 02:41:48PM CEST:
> > > On Sat, Sep 02, 2006 at 12:09:49PM +0200, Ralf Wildenhues wrote:
> > >
> > > > But that public version would have to include the cast to long int,
> > > > for the HP compiler, which would be at least a bit ugly. 
> > > 
> > > Ralf, could you please give me a reference to the problem?
> > 
> > See the comment in the implementation of AC_CHECK_SIZEOF.
> 
> Well, it only says that `sizeof(foo) >= 0' has problems.

Yes, but I noticed the issue with AC_CHECK_ALIGNOF as well.
http://lists.gnu.org/archive/html/autoconf-patches/2006-03/msg00006.html

Also, see the more verbose description in autoconf.info(Specific
Compiler Characteristics).  And more indication that this bug (or these
bugs; it's not clear to me there was just one) is of different nature:
http://lists.gnu.org/archive/html/autoconf-patches/2002-02/msg00001.html
http://lists.gnu.org/archive/html/autoconf-patches/2001-10/msg00087.html

Unfortunately (well, not really ;-), it seems the compiler I have access
to has recently been upgraded and does not have this bug any more.
(FWIW, I haven't tried HP testdrive compilers.)

> I do not see what workaround is needed for `sizeof (ptrdiff_t) <=
> sizeof (int)', if any.  Perhaps
>   (long int) sizeof (ptrdiff_t) <= (long int) sizeof (int) ?
> I do not think that we want
>   (long int) (sizeof (ptrdiff_t) <= sizeof (int))

Actually, why not?  (This is an honest question!)

> Anyway, I would suggest to modify ptrdiff_max.m4 to use
> AC_LANG_BOOL_COMPILE_IFELSE([sizeof (ptrdiff_t) <= sizeof (int)])
> and wait for a bug report.

I'd definitely object this suggestion.

Cheers,
Ralf