[Python-Dev] C99

[Brett Cannon]

On Fri, 5 Aug 2016 at 15:17 Guido van Rossum <gvanrossum at gmail.com> wrote:

> I want it to list specific versions that are known to be good right
> now, so we can point fingers appropriately when a regression happens.
>

OK, then we could pin it to MSVC 2016, gcc 6.1, and clang 3.8.1 which are
the latest releases (unless I'm missing a compiler we all feel like we
should officially support).


> If you have to ask Steve what version he used, ask!
>

I know of what compiler has been used by Steve, I was just trying to give a
very loose example of how it could be phrased if we wanted a shifting
window of support based on what was available at the time of release for
Python instead of the "what was available Aug 2016" static specification
that you said you wanted.


>
> On Fri, Aug 5, 2016 at 3:15 PM, Brett Cannon <brett at python.org> wrote:
> >
> >
> > On Fri, 5 Aug 2016 at 15:07 Guido van Rossum <gvanrossum at gmail.com>
> wrote:
> >>
> >> That sounds fine to me, but we need to list specific compiler versions.
> >
> >
> > Would you want this to be static (e.g. MSVC 2016 until we choose to
> update
> > to support C11), or would you want it to vary based on what's available
> when
> > the current/last Python is/was released (e.g. whatever version of MSVC
> Steve
> > uses to build the binaries for 3.5 or 3.6 in our current case)?
> >
> >>
> >>
> >> On Fri, Aug 5, 2016 at 2:04 PM, Brett Cannon <brett at python.org> wrote:
> >> > Where did we finally land on this discussion? Do we want to update
> PEP 7
> >> > to
> >> > say that starting in 3.6 we may use C99 features common to all
> supported
> >> > compilers and list what those compilers are (i.e. gcc, clang, and
> MSVC)?
> >> >
> >> > On Wed, 8 Jun 2016 at 01:28 Victor Stinner <victor.stinner at gmail.com>
> >> > wrote:
> >> >>
> >> >> I guess that as usual, we should use the "common denominator" of all
> >> >> compilers supported by CPython. For example, if MSVC doesn't support
> a
> >> >> feature, we should not use it in CPython.
> >> >>
> >> >> In practice, it's easy to check if a feature is supported or not: we
> >> >> have buildbots building Python at each commit. It was very common to
> >> >> get a compilation error only on MSVC when a variable was defined in
> >> >> the middle of a function. We are now using
> >> >> -Werror=declaration-after-statement with GCC because of MSVC!
> >> >>
> >> >> Maybe GCC has an option to ask for the subset of the C99 standard
> >> >> compatible with MSVC? Something like "-std=c99 -pedantic"?
> >> >>
> >> >> Note: I tried -pedantic, GCC emits a lot of warnings on code which
> >> >> looks valid and/or is protected with #ifdef for features specific to
> >> >> GCC like computed goto.
> >> >>
> >> >> Victor
> >> >>
> >> >> 2016-06-07 21:45 GMT+02:00 Guido van Rossum <gvanrossum at gmail.com>:
> >> >> > We should definitely keep supporting MSVC.
> >> >> >
> >> >> > --Guido (mobile)
> >> >> >
> >> >> > On Jun 7, 2016 12:39 PM, "Sturla Molden" <sturla.molden at gmail.com>
> >> >> > wrote:
> >> >> >>
> >> >> >> Victor Stinner <victor.stinner at gmail.com> wrote:
> >> >> >>
> >> >> >> > Is it worth to support a compiler that in 2016 doesn't support
> the
> >> >> >> > C
> >> >> >> > standard released in 1999, 17 years ago?
> >> >> >>
> >> >> >> MSVC only supports C99 when its needed for C++11 or some MS
> >> >> >> extension
> >> >> >> to
> >> >> >> C.
> >> >> >>
> >> >> >> Is it worth supporting MSVC? If not, we have Intel C, Clang and
> >> >> >> Cygwin
> >> >> >> GCC
> >> >> >> are the viable options we have on Windows (and perhaps
> Embarcadero,
> >> >> >> but
> >> >> >> I
> >> >> >> haven't used C++ builder for a very long time). Even MinGW does
> not
> >> >> >> fully
> >> >> >> support C99, because it depends on Microsoft's CRT. If we think
> MSVC
> >> >> >> and
> >> >> >> MinGW are worth supporting, we cannot just use C99
> indiscriminantly.
> >> >> >>
> >> >> >> _______________________________________________
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> >> >> >> Unsubscribe:
> >> >> >>
> >> >> >>
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> >> >> >
> >> >> >
> >> >> > _______________________________________________
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> >> >> >
> >> >> >
> >> >> >
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> >> >> >
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> >> >>
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> >>
> >>
> >>
> >> --
> >> --Guido van Rossum (python.org/~guido)
>
>
>
> --
> --Guido van Rossum (python.org/~guido)
>
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