From: Jakub Jelinek <jakub@redhat.com>
To: Marek Polacek <polacek@redhat.com>
Cc: "Joseph S. Myers" <joseph@codesourcery.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
Richard Biener <rguenther@suse.de>,
Jason Merrill <jason@redhat.com>
Subject: Re: [C PATCH] Disallow subtracting pointers to empty structs (PR c/58346)
Date: Wed, 15 Jan 2014 10:35:00 -0000 [thread overview]
Message-ID: <20140115103540.GY892@tucnak.redhat.com> (raw)
In-Reply-To: <20140115102737.GJ4458@redhat.com>
On Wed, Jan 15, 2014 at 11:27:37AM +0100, Marek Polacek wrote:
> Perhaps, but I don't think we can do it easily. Consider
>
> int
> foo (int *p, int *q)
> {
> return p - q;
> }
That is not a difference of pointers to zero sized arrays though,
that is pointers to int, and there is no division by zero involved, you can
get 0 as the result of course.
I think Joseph meant say
__PTRDIFF_TYPE__
foo (int p[3][0], int q[3][0])
{
return p - q;
}
which is also (((long int) p - (long int) q) /[ex] 0).
Jakub
next prev parent reply other threads:[~2014-01-15 10:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-13 16:32 Marek Polacek
2014-01-13 17:21 ` Florian Weimer
2014-01-13 17:22 ` Marek Polacek
2014-01-13 20:48 ` Marek Polacek
2014-01-14 14:39 ` Jason Merrill
2014-01-14 17:52 ` Florian Weimer
2014-01-15 9:12 ` Marek Polacek
2014-01-14 21:42 ` Joseph S. Myers
2014-01-15 10:27 ` Marek Polacek
2014-01-15 10:35 ` Jakub Jelinek [this message]
2014-01-15 13:50 ` Marek Polacek
2014-01-15 21:23 ` Joseph S. Myers
2014-01-16 18:52 ` Marek Polacek
2014-01-23 9:15 ` Marek Polacek
2014-01-23 17:47 ` Joseph S. Myers
2014-01-16 11:50 ` Eric Botcazou
2014-01-16 11:58 ` Marek Polacek
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