Bug#696422: warnings for missing Built-Using

[Ansgar Burchardt <ansgar@debian.org>]

Package: lintian
Version: 2.5.10.3
Severity: wishlist

It would be nice if lintian would emit a warning for packages that might miss a
Built-Using field (Policy 7.8). There are two cases where a Built-Using field
is needed:

Using source from another package. Lintian could look at debian/control and
look for a Build-Depends on *-source or *-source-[0-9.]+, but no binary package
having Built-Using.

This would result in false positives for:
- Packages not using substitution variables for Built-Using, but adding
  the field directly. But the packages I have seen that have a Built-Using
  field were all using a substition variable.
- *-source packages that do not provide source and are used in
  Build-Depends.

The other case are statically linked programs that include static libraries
from other packages. A simple check would be to look for packages that include
static binaries, but no Built-Using field. However this would result in false
positives for binaries not linking libraries from other packages, so I'm not
sure how useful such a check would be.

Ansgar