[Python-Dev] C99 (original) (raw)

Steve Dower steve.dower at python.org
Fri Aug 5 22:15:30 EDT 2016

FYI, it's MSVC 14.0 (which is included in VS 2015).

Personally I'd like to see it restricted to the common subset of C99 and some version of C++ (which is obviously mostly C and includes no C++), because I know there are a few things in C99 only that are very obscure because they aren't also in C++.

I'd settle for saying that all header files must be C++ compatible so that embedders and extenders have the option of C or C++, even if we allow the obscure parts of C99 inside our code.

Cheers, Steve

Top-posted from my Windows Phone

-----Original Message----- From: "Brett Cannon" <brett at python.org> Sent: ‎8/‎5/‎2016 15:44 To: "Guido van Rossum" <gvanrossum at gmail.com> Cc: "Python-Dev" <python-dev at python.org>; "Sturla Molden" <sturla.molden at gmail.com> Subject: Re: [Python-Dev] C99

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. >> _>> ________________________ >> Python-Dev mailing list >> Python-Dev at python.org >> https://mail.python.org/mailman/listinfo/python-dev >> Unsubscribe: >> https://mail.python.org/mailman/options/python-dev/guido%40python.org > > _> ________________________ > Python-Dev mailing list > Python-Dev at python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > > https://mail.python.org/mailman/options/python-dev/victor.stinner%40gmail.com >

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