This is the mail archive of the
mailing list for the GCC project.
Re: nonnull, -Wnonnull, and do/while
- From: Stefan Sobernig <ss at thinkersfoot dot net>
- To: Jakub Jelinek <jakub at redhat dot com>, Marek Polacek <polacek at redhat dot com>, Mark Wielaard <mjw at redhat dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 18 Feb 2016 00:21:39 +0100
- Subject: Re: nonnull, -Wnonnull, and do/while
- Authentication-results: sourceware.org; auth=none
- References: <56C2EF2C dot 4050508 at thinkersfoot dot net> <20160216100438 dot GR3163 at redhat dot com> <20160216101121 dot GO3017 at tucnak dot redhat dot com>
> On Tue, Feb 16, 2016 at 11:04:38AM +0100, Marek Polacek wrote:
>> On Tue, Feb 16, 2016 at 10:43:08AM +0100, Stefan Sobernig wrote:
>>> Under a recent gcc 6 [*], we run into -Wnonnull warnings using the
>>> nonnull attribute:
>> Yes, this warning has been enhanced for GCC 6.
>>> test.c: In function 'f':
>>> test.c:16:14: warning: nonnull argument 's' compared to NULL [-Wnonnull]
>>> } while (s != NULL);
>>> Am I missing sth.? Is this a false positive?
>> Well, it's just that "s" has the nonnull attribute so the compiler thinks it
>> should never be null in which case comparing it to null should be redundant.
>> Doesn't seem like a false positive to me, but maybe someone else feels
> The nonnull attribute should be solely about the value that is passed to the
> function, it doesn't tell anything about the value of the argument after
> it is changed. So IMHO this warning change should be reverted and instead
> we should warn somewhere soon after going into SSA, only when
> the SSA_NAME_IS_DEFAULT_DEF of the PARM_DECL which has non-NULL attribute
> is compared to NULL.
Am I supposed to file this as a bug report then, for the records? Or
will it be taken care of ...