Re: Re: #define __MUSL__ in features.h

["dgutson ." <danielgutson@gmail.com>]

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On Thu, Mar 15, 2018 at 4:32 PM, Rich Felker <dalias@libc.org> wrote:

> On Thu, Mar 15, 2018 at 04:02:03PM -0300, Martin Galvan wrote:
> > 2018-03-15 15:53 GMT-03:00 Rich Felker <dalias@libc.org>:
> > > In any case it's not a bug in musl. The code is perfectly valid C. If
> > > the compiler is producing a warning for it, either ignore it or ask
> > > the compiler to stop.
> >
> > Just because some code is valid C, it doesn't mean it's not buggy.
>
> It's valid C that does exactly what it's intended to do.
>
> > >> The compiler warnings aren't being wrongly produced. musl will indeed
> > >> perform a signed-to-unsigned conversion here.
> > >
> > > Because that's how the C language works.
> >
> > Yes. And gcc has checks to try and make up for C's weak typing.
> >
> > While your definition of "bug" is debatable, IMHO if a commonly used
> > option causes application builds to break due to some library, the
> > library has a usability issue. The issue is even bigger when we're
> > talking about something as core as the standard C library.
>
> Perhaps this should be documented more explicitly, but there is no
> guarantee that building with -Werror[=anything except warnings which
> are constraint violations in C] will succeed, especially when GCC is
> not honoring its usual promise not to produce warnings for code
> expanded from macros from -isystem paths. I did just test and indeed
> the warning is produced with gcc 6.3.0.
>
> > >> So whenever we find a bug on musl we should just stop all our
> > >> development until you've fixed the bug?
> > >
> > > No. As noted above, if you need to support systems that might have bug
> > > X, you write a test (configure-time or run-time as appropriate) to
> > > detect bug X and handle it.
> >
> > Precisely, and __MUSL__ would be really useful for this.
>
> Absolutely not. __MUSL__ would not tell you anything about whether bug
> X is present. It would facilitate permanently assuming "musl has bug
> X" because you observed bug X on musl at one point in the past.
>

Then turn __MUSL__ a number holding the version, as in cplusplus, etc, so
people can do

#if __MUSL__ < someversion
#endif

and it will be clear what happens and will solve the chronology issue.


>
> FWIW, mixing these two issues in one thread is not very productive.
> The warning issue is separate and should be discussed on its own.
>
> Rich
>



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