[Reproducible-builds] Bug#832099: lintian: please check for unnecessary SOURCE_DATE_EPOCH assignments

[Russ Allbery]

Mattia Rizzolo <mattia at debian.org> writes:
> On Fri, Jul 22, 2016 at 11:55:46AM +0200, Chris Lamb wrote:
>> Attached is the following:
>> 
>>   commit 3b10f7dbaecedb0a458c25cc0b8615b489d424af
>>   Author: Chris Lamb <lamby at debian.org>
>>   Date:   Fri Jul 22 10:54:02 2016 +0100
>>   
>>       c/rules: Check for unnecessary SOURCE_DATE_EPOCH assignments
>>       
>>       As of dpkg 1.18.8, this is no longer necessary as dpkg exports this
>>       variable if it is not already set (#759999). This should encourage
>>       removing some duplicated code from a lot of our rules files.

> though, using dpkg-buildpackage is not mandatory, a package should be
> able to build with just `debian/rules binary`.  In such case SDE
> wouldn't be exported.

> This looks fairly similar to e.g. DEB_HOST_ARCH & friends variables,
> that even if they are exported by dpkg-buildpackage you should set them
> in d/rules nonetheless.

> At least, that's what my AM told me back then ^^

I think that's fine in this case, since not setting that variable doesn't
break the build.  It just means the build isn't reproducible, which is an
optional feature.

I think it's fine for optional features to only be implemented by the
surrounding build wrapper or by environment variables explicitly set by
the person building the package.  In fact, it makes somewhat more sense to
me than having debian/rules unconditionally force a reproducible build.

In other words, I think this is more akin to DEB_BUILD_OPTIONS than it is
to DEB_HOST_ARCH.

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