Horton
Menu

Re: C99 compliance for src/port/snprintf.c

Andres Freund <andres@anarazel.de>

View thread
From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: David Steele <david@pgmasters.net>, pgsql-hackers@lists.postgresql.org
Date: 2018-08-15T22:40:26Z
Lists: pgsql-hackers 
Hi,

On 2018-08-15 18:31:10 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2018-08-15 18:13:59 -0400, Tom Lane wrote:
> >> Experimenting here says that even reasonably modern gcc's won't take
> >> declarations-inside-for without "--std=c99" or such.
> 
> > I think autoconf's magic knows about most of that:
> >  — Macro: AC_PROG_CC_C99
> 
> Ah, of course.  What about the MSVC build?

It looks like it mostly just enables that by default. But I only looked
cursorily.  It's a bit annoying because that makes it harder to be sure
which animals support what.  Looks like e.g. hammerkop (supposedly msvc
2005) might not support the subset we want; not that I'd loose sleep
over raising the minimum msvc in master a bit.


> > I think we could get a start by adding that test to configure, without
> > relying on it for now (i.e. keeping mylodon with -Wc99-extensions
> > -Werror=c99-extensions alive). That'd tell us about which machines,
> > besides presumably gaur, we'd need to either kick to the curb or change.
> 
> Sure, no objection to putting that in just to see how much of the
> buildfarm can handle it.  If the answer turns out to be "a lot",
> we might have to reconsider, but gathering data seems like the
> first thing to do.

Cool. Too late today (in Europe for a few more days), but I'll try to
come up with something tomorrow.

Greetings,

Andres Freund

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Remove test for VA_ARGS, implied by C99.

  2. Introduce minimal C99 usage to verify compiler support.

  3. Require C99 (and thus MSCV 2013 upwards).

  4. Require a C99-compliant snprintf(), and remove related workarounds.

  5. Try to enable C99 in configure, but do not rely on it (yet).

  6. Make snprintf.c follow the C99 standard for snprintf's result value.

  7. Clean up assorted misuses of snprintf()'s result value.