_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: 1359 bytes --]

[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.

Thanks,
Alex

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


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