On Monday 16 Dec 2013 04:04:34 eroen wrote:
> On Sun, 15 Dec 2013 17:37:53 +0100
> 
> Benjamin Block <bebl@zlug.org> wrote:
> > Most of the times, when some binary packages on my systems do cause
> > something like this, then I just unemerge the package that keeps
> > recompiling and emerge it again afterwards. This will cause the
> > portage to drop the library-references in question and add new ones.
> > 
> > So, this should do the trick:
> > 	emerge -C app-antivirus/avast4workstation
> > 	emerge -1 app-antivirus/avast4workstation
> 
> This will make the message from portage and the old library version go
> away, yes. It will also cause the program that used the library
> (/opt/avast4workstation/bin/avastgui in OP's case) crash when you try
> to run it, due to the old library version not being installed.
> 
> The correct solution to this is to add the specific (old) version of the
> library to the dependencies (in the ebuild) of the (binary) package that
> uses it. This will prevent an upgrade that uninstalls the old library
> version. Sometimes the maintainer of the library will add a slotted
> version of it, so that non-binary users of it do not have to use the
> outdated version.
> 
> If the binary package is not an ebuild, you can manually add the newer
> library version to package.mask, or make sure that the slot for the
> older version is installed if the library is slotted.
> 
> Better yet (in all cases), get a more recent version of the binary
> package that is built against the newer version of the library.
> Complain to the vendor if none is available :-)
> 
> The preserve-libs feature in portage is intended to let things keep on
> working short-term for source-distributed packages. In that case, the
> currently installed program is linked against the old library version,
> and when the program is rebuilt (with @preserved-rebuild) it will be
> linked against the newer version.

Thank you for a detailed explanation, which makes sense to me.  You are right, 
uninstalling, running @preserved-rebuild and reinstalling this package breaks 
the avastgui because of the missing libpangox-1.0.so.0 library.  Thankfully, 
the command line function is unaffected.

I wouldn't want to keep old libraries around unnecessarily, so I may have to 
chase the dev for this package and see if he's still interested to look after 
it.
-- 
Regards,
Mick