Bug#683596: lintian: False positive "unused-override" when checking multiple packages with lintian

[Matthijs Kooijman <matthijs@stdin.nl>]

Package: lintian
Version: 2.5.10
Severity: normal

Hi folks,

I just stumbled upon lintian giving me a false "unused-override"
tag. This happens when you override some tag because the file
needed for it is in another package, but then run lintian on both
packages involved: Lintian now finds the file in the other package,
doesn't trigger the warning and thinks the override is unused.

In this particular case, I was overriding the menu-icon-missing tag
in the openttd package, since the menu icon is in the openttd-data
package (which openttd depens on).

To reproduce (I removed an unrelated binary-without-manpage tag from
below output for clarity):

	matthijs@grubby:/tmp$ wget http://snapshot.debian.org/archive/debian/20120602T033850Z/pool/main/o/openttd/openttd_1.2.1-1_amd64.deb
	matthijs@grubby:/tmp$ wget http://snapshot.debian.org/archive/debian/20120602T033850Z/pool/main/o/openttd/openttd-data_1.2.1-1_all.deb

	matthijs@grubby:/tmp$ lintian --no-override -I openttd_1.2.1-1_amd64.deb
	W: openttd: menu-icon-missing usr/share/pixmaps/openttd.32.xpm

	matthijs@grubby:/tmp$ lintian --show-overrides -I openttd_1.2.1-1_amd64.deb
	N: All icons are in openttd-data, which openttd depends on.
	O: openttd: menu-icon-missing usr/share/pixmaps/openttd.32.xpm

	matthijs@grubby:/tmp$ lintian --show-overrides -I openttd_1.2.1-1_amd64.deb openttd-data_1.2.1-1_all.deb
	I: openttd: unused-override menu-icon-missing usr/share/pixmaps/openttd.32.xpm

	matthijs@grubby:/tmp$ lintian --no-override -I openttd_1.2.1-1_amd64.deb openttd-data_1.2.1-1_all.deb

I don't think there's any way right now I can build my package such that
it is lintian clean both when checking with just openttd and when
checking openttd and openttd-data in the same lintian run (e.g., when
running lintian on the .changes file).

I'm not sure what the proper fix for this is. Perhaps each check should
detect that it's _not_ firing because there are multiple packages (and
it would have fired if the packages were processed separately), or
perhaps for each apparently unused override, the given check should be run
on each package separately to see if it's really unused?

Gr.

Matthijs

-- System Information:
Debian Release: wheezy/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.5.0-rc3-wl+ (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages lintian depends on:
ii  binutils                       2.22-6.1
ii  bzip2                          1.0.6-3
ii  diffstat                       1.55-3
ii  file                           5.11-1
ii  gettext                        0.18.1.1-9
ii  hardening-includes             2.2
ii  intltool-debian                0.35.0+20060710.1
ii  libapt-pkg-perl                0.1.26+b1
ii  libarchive-zip-perl            1.30-6
ii  libc-bin                       2.13-33
ii  libclass-accessor-perl         0.34-1
ii  libclone-perl                  0.31-1+b2
ii  libdpkg-perl                   1.16.4.3
ii  libemail-valid-perl            0.190-1
ii  libipc-run-perl                0.91-1
ii  libparse-debianchangelog-perl  1.2.0-1
ii  libtimedate-perl               1.2000-1
ii  liburi-perl                    1.60-1
ii  locales                        2.13-33
ii  man-db                         2.6.2-1
ii  patchutils                     0.3.2-1.1
ii  perl [libdigest-sha-perl]      5.14.2-12

lintian recommends no packages.

Versions of packages lintian suggests:
pn  binutils-multiarch     <none>
ii  dpkg-dev               1.16.4.3
ii  libhtml-parser-perl    3.69-2
pn  libperlio-gzip-perl    <none>
pn  libtext-template-perl  <none>
ii  man-db                 2.6.2-1
ii  xz-utils [lzma]        5.1.1alpha+20120614-1

-- no debconf information