some background and possible fixes for file collisions

file-blockers-dev-handbook-text (text/plain), 1.42 KB, created by Marius Mauch (RETIRED) on 2005-03-07 16:31:02 UTC

When you encounter a package that is trying to install files that are already 
provided by another package (detectable with FEATURES=collision-protect for example)
you have to fix this situation before you can commit the ebuild or, if you encounter
this with an existing package, file a bug about that package (see below for a few exceptions).
The reason while file conflicts are critical is because if "foo" provides
the file /usr/bin/bla and "bar" is going to overwrite it, and later "bar" is unmerged
portage will remove /usr/bin/bla  and therefore likely break "foo".
The most obvious fix is to add a blocking dependency to both packages that want to
install that file, so they can't be installed at the same time. But unless there
are also other reasons for those packages to block each other you should avoid this 
if possible and rather fix the package, which could include one or more of the following steps:
- make "foo" (R)DEPEND on "bar"
- remove conflicting files from "foo" in src_install or pkg_preinst
- move conflicting files into a new subpackage and make "foo" and "bar" both (R)DEPEND on that package
- change location where "foo" installs conflicting files

In some cases conflicting files can't be really fixed or aren't critical, 
currently known exceptions are perl module manpages (overwriting the ones 
from perl itself) and CONFIG_PROTECTed files (should still be fixed, but 
aren't critical as portage won't overwrite them).