Bug#687001: ITP: optional-dev -- fake (empty) dev package

[Dmitry Smirnov <onlyjob@member.fsf.org>]

On Sun, 9 Sep 2012 02:06:52 Paul Wise wrote:
> I would be interested to see what real use-cases people wanted this
> sort of thing for. Dimitry, which specific problem were you trying to
> solve when you came up with optional-dev?

Thanks Paul, primarily I was trying to address a problem when package build 
unnecessarily fails due to lack of "optional" dependency before an actual 
attempt to build.

Due to risk of FTBFS maintainer should be careful with introducing 
dependencies that are non-critical for upstream build.
In this case, enabling optional feature by adding dependency may make package 
build more fragile and create some difficulties for backporting as 
distinguishing required build-dependencies from optional ones may be not 
obvious.

Now it became clear that idea is not feasible because it creates more problem 
than it solves.

Thanks to feedback from Adam, Neil, Brian, Arno, Guillem, Simon, Geregor, 
Bastian and others I can summarise the flaws in the idea:

* buildd servers can't fall back to alternative so even if we can avoid
  FTBFS in pbuilder by providing a trivially satisfiable fallback
  dependency, that is not the case for our build servers.

* Rarely some packages may be not available for build due to transition,
  breakage or other circumstances. With silent fallback instead of FTBFS
  package may suddenly and unexpectedly lost some of its functionality.

* NMUs are not guaranteed to be the same as original package due to
  possibility of missing optional dependency packages in the environment
  where NMU is being prepared.


> > But I see the use case, e.g. for packages that rebuild the
> > documentation if some tool is available and just skip it gracefully
> > and use the shipped version, if not.
> 
> We have the bootstrap stuff for that:
> 
> http://wiki.debian.org/DebianBootstrap

Very interesting, thank you.

Regards,
Dmitry.