Bug#1064648: allegro5-doc: please make the build reproducible.

[James Addison]

Hi Andreas,

On Thu, 9 May 2024 at 11:17, Andreas Rönnquist <gusnan at debian.org> wrote:
>
> Those fixes was obviously not enough, just see the repro reports.

Ok, yep - thanks for checking those.

When I check the reports, most of the remaining problems seem to relate to
duplicate definitions appearing in the documentation (for example, a definition
for "al_color_cmyk" appearing twice).

> The strange thing is that it according to the tests does seem to build
> reproducible on arm64...

Puzzling indeed.  I'll have another read through the codebase soon.

> One other detail is that on armhf the only change seems to be the
> architecture which is included in the ALLEGRO_PKG_HOST_SYSTEM variable.
>
> Is there some magic like SOURCE_DATE_EPOCH to use that would avoid this
> problem in this case?

Not as far as I'm aware, no - for SOURCE_DATE_EPOCH, there is a range of
possible integer values that are all equally valid, so it's straightforward to
select one to make a package build reproducible.  Specifiying an arbitrary but
static architecture could be at-least challenging, and at-worst misleading or
potentially compatibility-breaking.

In this kind of situation I'd generally recommend working backwards to figure
out whether -- and if so, how -- the nondeterministic value is used.  I didn't
find any search results for ALLEGRO_PKG_HOST_SYSTEM in Debian codesearch[1],
so I'd recommend a reprotest build after removing it to see whether that
succeeds (I'll try this soon).

Regards,
James

[1] - https://codesearch.debian.net/search?q=ALLEGRO_PKG_HOST_SYSTEM

[2] - https://salsa.debian.org/reproducible-builds/reprotest