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From: Alejandro Colomar
Sent: Sunday, December 01, 2024 17:24
To: qing.z...@oracle.com
Cc: f...@deneb.enyo.de; gcc@gcc.gnu.org; ja...@redhat.com; josmy...@redhat.com;
libc-al...@sourceware.org; uec...@tugraz.at; Chris Bazley
Subject: Re: Handling C2Y zero-length operations
> > And get clarified the qsort/bsearch cases whether it is about just
> > nmemb == 0 or nmemb * size == 0.
>
> C does not support zero-sized objects, so that's something for us to
> figure out on our own. We can treat size == 0 as invalid because the
> functions can't work, as they use pointers
Hi,
I had a discussion about this with another WG14 member when this was
voted in. We both voted against, because this is nefarious for static
analysis.
However, I think this can be though to resemble how 'const' works in the
standard:
const char cbuf[10];
memcpy((char *)cbuf,
> On Nov 12, 2024, at 01:51, Martin Uecker wrote:
>
> Am Montag, dem 07.10.2024 um 15:14 + schrieb Qing Zhao:
>>
>>> On Oct 7, 2024, at 10:13, Jakub Jelinek via Gcc wrote:
>>>
>>> On Fri, Oct 04, 2024 at 12:42:24AM +0200, Florian Weimer wrote:
* Joseph Myers:
> The real qu
Am Dienstag, dem 12.11.2024 um 07:51 +0100 schrieb Martin Uecker:
> Am Montag, dem 07.10.2024 um 15:14 + schrieb Qing Zhao:
> >
> > > On Oct 7, 2024, at 10:13, Jakub Jelinek via Gcc wrote:
> > >
> > > On Fri, Oct 04, 2024 at 12:42:24AM +0200, Florian Weimer wrote:
> > > > * Joseph Myers:
> >
Am Montag, dem 07.10.2024 um 15:14 + schrieb Qing Zhao:
>
> > On Oct 7, 2024, at 10:13, Jakub Jelinek via Gcc wrote:
> >
> > On Fri, Oct 04, 2024 at 12:42:24AM +0200, Florian Weimer wrote:
> > > * Joseph Myers:
> > >
> > > > The real question is how to achieve optimal warnings in the absenc
> On Oct 7, 2024, at 11:22, Jakub Jelinek wrote:
>
> On Mon, Oct 07, 2024 at 03:14:22PM +, Qing Zhao wrote:
>>> Consider the qsort case. My understanding was that the paper is making
>>> typedef int (*cmpfn) (const void *, const void *);
>>> qsort (NULL, 0, 1, (cmpfn) NULL);
>>> valid (but
On Mon, Oct 07, 2024 at 03:14:22PM +, Qing Zhao wrote:
> > Consider the qsort case. My understanding was that the paper is making
> > typedef int (*cmpfn) (const void *, const void *);
> > qsort (NULL, 0, 1, (cmpfn) NULL);
> > valid (but is
> > qsort (NULL, 1, 0, (cmpfn) NULL);
> > still inval
> On Oct 7, 2024, at 10:13, Jakub Jelinek via Gcc wrote:
>
> On Fri, Oct 04, 2024 at 12:42:24AM +0200, Florian Weimer wrote:
>> * Joseph Myers:
>>
>>> The real question is how to achieve optimal warnings in the absence of the
>>> attribute. Should we have a variant of the nonnull attribute t
* Jakub Jelinek:
> How do you express that with access attribute, which can only have 1
> size argument?
Don't we sometimes use inline functions to handle such special cases?
> For the rest, perhaps we need some nonnull_if_nonzero argument
> which requires that the parameter identified by the fi
On Fri, Oct 04, 2024 at 12:42:24AM +0200, Florian Weimer wrote:
> * Joseph Myers:
>
> > The real question is how to achieve optimal warnings in the absence of the
> > attribute. Should we have a variant of the nonnull attribute that warns
> > for NULL arguments but without optimizing based on t
On 2024-10-03 15:42, Florian Weimer wrote:
I think attribute access already covers part of it:
The GCC documentation for attribute access[1] is unclear as to whether
the pointer is allowed to be null when the size is zero. Perhaps we
could ask the GCC maintainers to document that it's allowed
* Joseph Myers:
> The real question is how to achieve optimal warnings in the absence of the
> attribute. Should we have a variant of the nonnull attribute that warns
> for NULL arguments but without optimizing based on them?
I think attribute access already covers part of it:
#include
void
WG14 accepted https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3322.pdf
at this week's meeting in Minneapolis, allowing various zero-length
language and library operations on null pointers in C2Y (in support of the
idiom where an empty array may be represented by a null pointer with zero
lengt
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