Bug#666726: debian-policy: Clarify if empty control fields are ollowed or not

[Henrique de Moraes Holschuh <hmh@debian.org>]

On Sat, 22 Nov 2014, Charles Plessy wrote:
> Le Fri, Nov 21, 2014 at 10:56:15AM +0100, Bill Allombert a écrit :
> > What about automatically generated control files and substvar ?
> > e.g.
> > Depends: ${misc:Depends}
> > where ${misc:Depends} resolve to the empty string ?
> > 
> > Does dpkg-gencontrol take care of that ? In that case we should not lead people
> > to believe that the above is incorrect.
> 
> a quick check where I added "Recommends: ${misc:Recommends}" and "Suggests:" to
> the source control file of the "hello" package suggests that empty fields
> are removed by default.

Empty fields in debian/control must be valid in *source* packages.  It is a
widely used feature of the dpkg-dev suite, and it has been around for a very
very long time AFAIK.

I don't think they are allowed in binary packages (deb/udeb), though.

I suggest we add explicit documentation in policy to reflect reality: the
package build process must accept empty fields in the debian/control file of
the source package being built, and must remove all empty fields from the
control file of the binary packages the package build process generates.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh