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From: Bruno Haible <bruno@clisp.org>
To: bug-gnulib@gnu.org, Bernhard Voelker <mail@bernhard-voelker.de>
Subject: Re: test-getgroups.c:stringop-overflow warning on newer GCC
Date: Fri, 01 Jan 2021 13:56:53 +0100	[thread overview]
Message-ID: <2887419.1QkhuepXuh@omega> (raw)
In-Reply-To: <d6a2d23c-1514-a50b-1e8d-3a749ef647c5@bernhard-voelker.de>

Hi Berny,

Bernhard Voelker wrote in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-12/msg00090.html>:
> Newer GCC complains about this test:
> 
>   $ make test-getgroups.o V=1
>   depbase=`echo test-getgroups.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
>   gcc -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I..  -DIN_FINDUTILS_GNULIB_TESTS=1 -I. -I. -I.. -I./.. -I../gl/lib -I./.. \
>     /gl/lib   -g -O2 -MT test-getgroups.o -MD -MP -MF $depbase.Tpo -c -o test-getgroups.o test-getgroups.c &&\
>   mv -f $depbase.Tpo $depbase.Po
>   In file included from test-getgroups.c:31:
>   test-getgroups.c: In function 'main':
>   test-getgroups.c:65:11: warning: argument 1 value -1 is negative [-Wstringop-overflow=]
>      65 |   ASSERT (getgroups (-1, NULL) == -1);
>         |           ^~~~~~~~~~~~~~~~~~~~

I can't reproduce this with a testdir created through
  ./gnulib-tool --create-testdir --dir=... --single-configure getgroups
and GCC 10.2.0, even with '-Wall' (whereas the GCC invocation that you show does
not invoke any warning options!):

$ gcc -DHAVE_CONFIG_H -I. -I..  -DGNULIB_STRICT_CHECKING=1 -DIN_GNULIB_TESTS=1 -I. -I. -I.. -I./.. -I../gllib -I./../gllib   -g -O2 -c test-getgroups.c -Wall
(no diagnostics)

Also, it's strange that this warning reports to come from -Wstringop-overflow
— whereas 'getgroups' is not a string operation.

So, to me it looks like a bug in the particular GCC version that you are using.

Under regular circumstances, I would consider adding a #pragma GCC diagnostic,
as you suggest, but not under these circumstances.

Bruno



  reply	other threads:[~2021-01-01 12:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-08 22:57 test-getgroups.c:stringop-overflow warning on newer GCC Bernhard Voelker
2021-01-01 12:56 ` Bruno Haible [this message]
2021-01-02  1:43   ` Bernhard Voelker
2021-01-02  1:59     ` Bruno Haible
2021-01-02  2:30       ` Bernhard Voelker
2021-01-02  3:33         ` Paul Eggert
2021-01-02 12:51           ` Bruno Haible
2021-01-02 19:21             ` Bernhard Voelker

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