Re: new module 'sigsegv'

[Dmitry V. Levin]

Hi,

On Mon, Jun 07, 2021 at 02:49:35AM +0200, Bruno Haible wrote:
[...]
> > -volatile int *
> > +static volatile int *
> >  recurse_1 (int n, volatile int *p)
> >  {
> >    if (n < INT_MAX)
> > @@ -80,7 +80,7 @@ recurse_1 (int n, volatile int *p)
> >    return p;
> >  }
> >  
> > -int
> > +static int
> >  recurse (volatile int n)
> >  {
> >    return *recurse_1 (n, &n);
> 
> This part should better not be applied. It may enable compiler optimizations
> (now or in the future) that, in the end, turn an endless recursion into an
> endless loop.

I'm not sure there is any difference left in the modern world of
lto-enabled compilers.  Anyway, in most cases warnings issued by
-Wmissing-prototypes are not related to functions with volatile return
types, so making them static shouldn't affect the result.

> > @@ -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.
> 
> I think the right fix would be that gnulib-tool's --import/--update
> option, when creating a tests directory, adds a $(CFLAG_ALLOW_WARNING)
> to tests/Makefile.am, where CFLAG_ALLOW_WARNING is defined as
>   -Wno-error  when the compiler is GCC or clang,
>   empty       otherwise
> Will that work in GNU grep?

GNU grep explicitly disables some warnings and enables -Werror for gnulib
tests [1][2], so I'd like to ask Jim what's the preferred way of handling
this in GNU grep.

[1] 
https://git.savannah.gnu.org/gitweb/?p=grep.git;a=commitdiff;h=v3.6-2-g623008c
[2] 
https://git.savannah.gnu.org/gitweb/?p=grep.git;a=commitdiff;h=v3.6-17-g74cda43

-- 
ldv