[bug#70169] [PATCH v2 04/12] maint: Help help2man generate reproducible man-pages.

[Janneke Nieuwenhuizen <janneke@gnu.org>]

pelzflorian (Florian Pelz) writes:

Hello Florian,

> Janneke Nieuwenhuizen <janneke@gnu.org> writes:
>> diff --git a/doc/local.mk b/doc/local.mk
>> +SOURCE_DATE_EPOCH = $(shell git show HEAD --format=%ct --no-patch 2>/dev/null || echo 0)
>> +export SOURCE_DATE_EPOCH
>
> Do I interpret correctly that “echo 0” is a fallback timestamp?

Yes.

> Looking at the now gone instructions from “git show
> 83c60bb0622440afe98930820186ddfa1e6e8b2f”, at that time, a timestamp of
> 1 was used for the tarball; I do not remember why.  In
> guix/scripts/pack.scm, 1 is used for squashfs and docker images.

That's probably because of build dependencies.

> Is 1 a better timestamp than 0?

For files, using 1 is preferrable if it's not a source file.  We use 1
for .go files, and 0 for .scm files, iirc.  SOURCE_DATE_EPOCH is (only)
used for the date in the document.  Without git, 0 is as good a guess
for a reproducible date for use in a document as any, I think.

Greetings,
Janneke

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