Re: coreutils and GCC -fanalyzer

[Pádraig Brady]

On 21/05/2020 13:29, Pádraig Brady wrote:
> On 21/05/2020 01:49, Paul Eggert wrote:
> > The coreutils patch installed on May 10 to pacify GCC 10 -fanalyzer
> > caused problems when I built coreutils with GCC 10.1.0. Some of the
> > newly-introduced pragmas generated diagnostics, and the pragmas didn't
> > seem to be needed in GCC 10.1.0 anyway. As 10.1.0 is the first public
> > release of GCC 10 I doubt whether we need to support GCC internal
> > versions (before GCC 10.1.0) that had problems with -fanalyze.
> >
> > Also, the patch seems to have introduced a bug in tsort.c due to a typo.
> > Less importantly, it introduced some new overhead in dd.c's non-lint
> > code (to save some pointers in global variables) that isn't needed and
> > might cause problems with other static checkers.
> >
> > To try to fix all this I installed the attached patches.
> >
> > At some point I hope this GCC 10 stuff settles down, as GCC 10.1.0 still
> > has bugs in the -fanalyzer area (e.g., see GCC bugs 93644, 95044, 95072)
> > and we don't want these bugs to adversely affect coreutils etc.
>
> Previously I was testing with the first Fedora 32 (public) GCC:
>     gcc (GCC) 10.0.1 20200328 (Red Hat 10.0.1-0.11)
>
> After just upgrading:
>     sudo dnf upgrade --advisory=FEDORA-2020-2c6c85202d
>     gcc (GCC) 10.1.1 20200507 (Red Hat 10.1.1-1)
>
> I can confirm that the comm.c pragma causes issues for gcc 10.1
>     src/comm.c:21:33: error: unknown option after '#pragma GCC diagnostic' kind 
> [-Werror=pragmas]
>      21 | # pragma GCC diagnostic ignored 
> "-Wanalyzer-use-of-uninitialized-value"
>
> The good news is that this is no longer needed to suppress
> -fanalyzer warnings, so we can just remove it.
>
> The other pragmas are still needed though to suppress -fanalyzer warnings.
>
> Also the dd change has minimal overhead and makes valgrind output cleaner.

Oh I see you improved the dd change, rather than remove it.

The attached patch on latest suppresses all warnings.
I also see with the latest gnulib that I also need to
pass -Wno-analyzer-too-complex to avoid very many such warnings.

cheers,
Pádraig

coreutils-fedora-fanalyzer.patch
Description: Text Data