Re: Building pg_xlogdump reproducibly

On Mon, Jan 04, 2016 at 04:51:25PM +0100, Andres Freund wrote:
> Hi,
>
> On 2016-01-04 15:59:46 +0100, Christoph Berg wrote:
> > The list of objects used to link pg_xlogdump is coming from
> > $(wildcard *desc.c) which returns them in filesystem order. This makes
> > the build result depend on this ordering, yielding different
> > compilation results.
>
> > -RMGRDESCSOURCES = $(notdir $(wildcard $(top_srcdir)/src/backend/access/rmgrdesc/*desc.c))
> > +RMGRDESCSOURCES = $(sort $(notdir $(wildcard $(top_srcdir)/src/backend/access/rmgrdesc/*desc.c)))
> > RMGRDESCOBJS = $(patsubst %.c,%.o,$(RMGRDESCSOURCES))
>
> That's probably not the only non-deterministic rule in postgres, given
> nobody paid attention tot that so far? At least transform modules added
> in 9.5 (hstore_plpython et al) look like they might similar issues.
>
> Wonder if we should instead define a wildcard wrapper in
> Makefile.global.in that does the sorting, including an explanation?

That sounds like it will avert a lot of pain in the future, and the
sort overhead is negligible compared to the build time.

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
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