Subject: Re: bug#23776: Perl's .pod files include timestamps, making Perl package builds non-deterministic

From: Leo Famulari <[email-masked]>
Date: Fri, 17 Jun 2016 14:50:17 -0400

On Fri, Jun 17, 2016 at 10:11:21AM +0200, Ludovic Courtès wrote:
> Leo Famulari <[email-masked]> skribis:
> 
> > On Thu, Jun 16, 2016 at 01:33:46PM +0200, Ludovic Courtès wrote:
> >> The problem is described in <git://git.debian.org/git/reproducible/notes.git>:
> >> 
> >> --8<---------------cut here---------------start------------->8---
> >> timestamps_in_documentation_generated_by_podman:
> >>   description: |
> >>     The module Pod::Man includes timestamps in its embedded manpages:
> >>     http://sources.debian.net/src/perl/latest/cpan/podlators/lib/Pod/Man.pm/?hl=1700#L977
> >>     They should be based on the mtime of the original file.
> >>   url: https://wiki.debian.org/ReproducibleBuilds/TimestampsInManpagesGeneratedByPodMan
> >
> > According to the information on this page, we should set POD_MAN_DATE
> > while building. Should we make the perl-build-system export this
> > variable? Set to SOURCE_DATE_EPOCH?
> 
> Yes, that sounds like a good idea.

Should I add a phase to %standard-phases in perl-build-system.scm [0]?

Should I define a new procedure set-POD_MAN_DATE [1] and add that
perl-build-system.scm's %standard-phases?

[0]
http://git.savannah.gnu.org/cgit/guix.git/tree/guix/build/perl-build-system.scm#n71

[1] As in...
http://git.savannah.gnu.org/cgit/guix.git/tree/guix/build/gnu-build-system.scm#n42