Debian and SOURCE_DATE_EPOCH=0

[Vagrant Cascadian]

On 2026-02-14, Ludovic Courtès wrote:
> Simon Josefsson via rb-general <rb-general at lists.reproducible-builds.org> skribis:
>
>> HP-UX 'make' treats mtime 0 as a missing file, and POSIX encourage it:
>>
>> https://lists.gnu.org/archive/html/bug-gnulib/2024-12/msg00209.html
>> https://lists.gnu.org/archive/html/bug-gnulib/2024-12/msg00227.html
>>
>> If you want to depend on GNU make behaviour, all is good.
>
> The Nix build daemon (and thus the Guix daemon) “forever” used mtime = 1
> to work around software that gives mtime == 0 special treatment:
>
>   https://github.com/NixOS/nix/commit/14bc3ce3d6d5745717fa19b8b43b5fdd117ff757
>
> It’s probably safer to avoid mtime == 0!

I have noticed a handful of packages in Guix which need a newer date,
notably no earlier 1980, but probably other corner cases as well...

Specifically, I recall at least one man page generator that only
work(s|ed) with SOURCE_DATE_EPOCH newer than ~1980 (although which
generator is not coming to me at the moment). There are a handful of
comments about dos filesystem timestamps not supporting earlier than
1980... so maybe that is a thing? I also see guix sprinkled with a few
other arbitrary values for SOURCE_DATE_EPOCH, although I will admit to
being the one who picked some of them in guix semi-arbitrarily... :)

But yeah, ideally figuring out a "meaningful" value for
SOURCE_DATE_EPOCH is ideal; picking arbitrary timestamps can be more
misleading that no timestamp at all... but we all make tradeoffs of
judgement at the time with the limited time(stamps) we have. :)

live well,
  vagrant
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