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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: 2018-08-16T11:18:59Z
Lists: pgsql-hackers 
On 2018-08-16 01:41:34 -0700, Andres Freund wrote:
> I've pushed a minimal version adding the C99 test.

So, we get:

* lotsa animals, unsurprisingly, showing C99 work without any flags.

  checking for ccache gcc option to accept ISO C99... none needed


* rhinoceros, nudibranch, grouse, ...:

  https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=rhinoceros&dt=2018-08-16%2008%3A45%3A01&stg=configure
  https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=nudibranch&dt=2018-08-16%2009%3A16%3A46&stg=configure
  https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=grouse&dt=2018-08-16%2009%3A17%3A25&stg=configure
  checking for ccache gcc option to accept ISO C99... -std=gnu99 (or variations thereof)

  So, the autoconf magic is doing it's thing here.


* dunlin (icc):

  https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=dunlin&dt=2018-08-16%2009%3A35%3A19&stg=configure
  checking for icc option to accept ISO C99... -std=gnu99

  (later fails, but not newly so, and just because of ENOSPC)

* anole (HP C compiler)

  https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=anole&dt=2018-08-16 09%3A32%3A19
  checking for cc option to accept ISO C99... none needed


* dromedary:

  https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=dromedary&dt=2018-08-16%2008%3A37%3A28&stg=configure
  checking for ccache gcc option to accept ISO C99... unsupported

  I suspect that's because of the '-ansi' flag in CFLAGS, not because
  the compiler is incapable of actually supporting C99.


Besides gaur, I'm also awaiting casteroides' results. The latter
definitely does support C99, but I'm not sure autconf pushes hard
enough.  I think every other relevant animal has reported back.

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.