From: Jim Meyering <jim@meyering.net>
To: Bruno Haible <bruno@clisp.org>
Cc: "bug-gnulib@gnu.org List" <bug-gnulib@gnu.org>
Subject: Re: warnings in unit tests
Date: Mon, 7 Jun 2021 22:55:56 -0700 [thread overview]
Message-ID: <CA+8g5KH=p2zo1JERfQpfjO4ouXqOikKWGFw++gwdmuKTNwZv2A@mail.gmail.com> (raw)
In-Reply-To: <2113844.jgEgOJX5uS@omega>
On Mon, Jun 7, 2021 at 7:41 PM Bruno Haible <bruno@clisp.org> wrote:
> Hi Jim,
>
> > > > > @@ -183,6 +183,9 @@ main ()
> > > > > *(volatile int *) (page + 0x678) = 42;
> > > > > break;
> > > > > case 3:
> > > > > +#if 6 < __GNUC__
> > > > > +# pragma GCC diagnostic ignored "-Wnull-dereference"
> > > > > +#endif
> > > > > *(volatile int *) 0 = 42;
> > > > > break;
> > > > > case 4:
> > > >
> > > > We shouldn't spend time eliminating warnings from test code.
> > > >
> > > > The goal is to have a good coverage of the lib/* code with unit tests.
> > > > That means, we need to
> > > > - make it easy to write unit tests,
> > > > - not make it time-consuming to maintain them.
> > > >
> > > > Eliminating warnings from lib/* code is useful, to avoid bugs in the
> > > > programs. But eliminating warnings from tests/* code goes against the
> > > > goal of increasing test coverage.
> >
> > Hi Bruno,
> > Isn't this code exceptional enough to merit three lines of warning suppression?
>
> No. Good unit tests do exceptional things, like calling close(-1), passing
> NULL pointers to various functions, and other things that e.g. Coverity
> warns about.
>
> > I would like to continue to use -Werror with most warning options even
> > in test code,
> > as long as the cost is low. This feels like a very low one-time cost.
>
> No, the cost is not low. Dmitry's patch also changed the linkage of 11
> functions. He did so to silence warnings (-Wmissing-prototypes) which are
> 1) not part of '-Wall',
> 2) just pointless for tests [my opinion as maintainer of most of these
> tests].
>
> I don't want the maintainers of packages that use Gnulib to push costs
> onto Gnulib, when it is just for their personal preference.
>
> The tests in Gnulib are there to evaluate the reliability of Gnulib's
> modules on a particular platform. The more test coverage we have, the
> better.
>
> Warnings in the unit tests are not problems. Test *failures* are problems.
>
> gnulib-tool has options --with-tests and --tests-base, that allow a
> package to ship the Gnulib tests and thus help Gnulib (by having more
> people run the unit tests and report possible test failures).
>
> If a package maintainer insists on having warning-free builds, I kindly
> ask them to not bundle the Gnulib tests any more — because requiring
> warning-free tests from Gnulib is more of an impediment than of a help.
>
> For those package maintainers who are OK to accept warnings in the
> Gnulib tests directory, on the other hand, I repeat my offer to
> automatically add -Wno-error in the tests/Makefile.am of that directory.
I can live without -Wmissing-prototypes in gnulib tests, but I still
remember times where using that option exposed a real bug.
My point about the cost/benefit was regarding that 3-line addition for
a single, deliberate NULL-deref.
That one really does not deserve to quash -Wnull-dereference for all tests.
next prev parent reply other threads:[~2021-06-08 5:56 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-16 17:01 new module 'sigsegv' Bruno Haible
2021-06-06 23:27 ` Dmitry V. Levin
2021-06-07 0:49 ` Bruno Haible
2021-06-07 10:29 ` Dmitry V. Levin
2021-06-08 1:45 ` Jim Meyering
2021-06-08 2:40 ` warnings in unit tests Bruno Haible
2021-06-08 5:55 ` Jim Meyering [this message]
2021-06-08 8:56 ` Bruno Haible
2021-06-09 0:41 ` Dmitry V. Levin
2021-06-10 20:05 ` Bruno Haible
[not found] ` <CAH8yC8kHTq5J9onJj+2jwy_DwzXrwujqFs9TEBxGh5k_KCu=kg@mail.gmail.com>
2021-06-08 10:57 ` Bruno Haible
2021-06-08 16:42 ` Paul Eggert
2021-06-09 13:35 ` Dmitry V. Levin
2021-06-09 19:38 ` Bruno Haible
2021-06-10 19:39 ` Bruno Haible
2021-06-09 7:23 ` Bernhard Voelker
2021-06-09 14:17 ` Bruno Haible
2021-06-10 8:13 ` Simon Josefsson via Gnulib discussion list
2021-06-10 19:51 ` Bruno Haible
2021-06-10 21:49 ` Simon Josefsson via Gnulib discussion list
2021-06-11 12:21 ` Eric Blake
2021-06-11 13:57 ` Bruno Haible
2021-06-19 12:02 ` new module 'sigsegv' Bruno Haible
2021-06-21 18:22 ` [PATCH] sigsegv, sigsegv-tests: Assign my contributions to the FSF Eric Blake
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