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

Andres Freund <andres@anarazel.de>

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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: 2018-08-16T08:41:34Z
Lists: pgsql-hackers 
Hi,

On 2018-08-15 18:31:10 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > 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.

I've pushed a minimal version adding the C99 test. If we were to
actually go for this permanently, we'd likely want to clean up a bunch
of other tests (say removing PGAC_C_VA_ARGS), but I don't see much point
in doing that while just gathering evidence (to the contrary, it seems
like it'd just muddy the water a bit).

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.