Bug#780259: perl: please make the output of Pod::Man reproducible

[Russ Allbery]

Axel Beckert <abe at debian.org> writes:
> Chris Lamb wrote:

>> While working on the "reproducible builds" effort [1], we have noticed
>> that Pod::Man generates output that varies depending on the current
>> timezone.

> While I appreciate the reproducible builds effort a lot, I don't think
> hardcoding UTC instead of the local timezone is suitable for general
> use.

> The patch is fine for building packages in Debian -- but I think,
> users using Debian's Pod::Man for their own projects will partially be
> confused by UTC times, especially those users not living in Europe or
> Africa, i.e. close to the GMT timezone.

Sorry, I was going to respond to this and didn't get to it.

As upstream maintainer of Pod::Man, I'm inclined to take this patch.  Some
of this is because I don't think there's a clearly right answer, and I
have a personal preference for using UTC for things like this.  Living on
the west coast of the US myself, my own blog posts (which use UTC) are
frequently dated in the "future" by local time, and I don't think it's
that big of a deal.

I do understand the concern over user confusion, but I also think it's
very valuable for pod2man to produce consistent output when given the same
input file, as a general principle of software design, regardless of local
variations like time zone settings.  For better or worse, the only
generally-agreed-upon reproducible date strategy is to use UTC.

It's trivial for people to override this behavior with the --date option
to pod2man or similar settings to the Pod::Man constructor if they don't
like the default, and I'll clearly document this in the package
documentation.  Since this is used only to generate a date, not a
timestamp, I think the maximum "error" is for the date to be off by about
14 hours, which, given how this software is used, is rarely going to be
significant.

-- 
Russ Allbery (rra at debian.org)               <http://www.eyrie.org/~eagle/>