Re: _Nullable and _Nonnull in GCC's analyzer (was: [PATCH v5] libio: Add nonnull attribute for most FILE * arguments in stdio.h)

[Alejandro Colomar <alx@kernel.org>]

[-- Attachment #1.1: Type: text/plain, Size: 1706 bytes --]

On 7/10/23 22:14, Alejandro Colomar wrote:
> [CC += Andrew]
> 
> Hi Xi, Andrew,
> 
> On 7/10/23 20:41, Xi Ruoyao wrote:
>> Maybe we should have a weaker version of nonnull which only performs the
>> diagnostic, not the optimization.  But it looks like they hate the idea:
>> https://gcc.gnu.org/PR110617.
>>
> This is the one thing that makes me use both Clang and GCC to compile,
> because while any of them would be enough to build, I want as much
> static analysis as I can get, and so I want -fanalyzer (so I need GCC),
> but I also use _Nullable (so I need Clang).
> 
> If GCC had support for _Nullable, I would have in GCC the superset of
> features that I need from both in a single vendor.  Moreover, Clang's
> static analyzer is brain-damaged (sorry, but it doesn't have a simple
> command line to run it, contrary to GCC's easy -fanalyzer), so having
> GCC's analyzer get over those _Nullable qualifiers would be great.
> 
> Clang's _Nullable (and _Nonnull) are not very useful outside of analyzer
> mode, as there are many cases where the compiler doesn't have enough
> information, and the analyzer can get rid of false negatives and
> positives.  See: <https://github.com/llvm/llvm-project/issues/57546>
> 
> I'll back the ask for the qualifiers in GCC, for compatibility with
> Clang.

BTW, Bionic libc is adding those qualifiers:

<https://android-review.googlesource.com/c/platform/bionic/+/2552567/7/libc/include/netinet/ether.h#45>
<https://android-review.googlesource.com/q/owner:zijunzhao@google.com+Nullability>

> 
> Thanks,
> Alex
> 

-- 
<http://www.alejandro-colomar.es/>
GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]