> Thanks for the feedback. However there's one thing I can't understand:
> whether the libraries are kept of removed is decided at the merge time,
> isn't it? So, whatever breaks, breaks when using "emerge" to update the
> offending library, the one that will break the ABI. So, how can using a
> tool *after that* have any impact over what's broken? It can fix the
> problem, but so can revdep-rebuild.
> I mean: if the old libs with the old abi's are kept, how it is relevant if
> you are using @preserved-rebuild, revdep-rebuild or another method, or none
> at all? Your programs will continue to work ok without needing to rebuild
> anything, won't them? And after rebuilding the package it's irrelevant
> *how* did you rebuild them... I must obviously be missing something here,
> if you have the time please, direct me to an adequate source of information
> or explain a bit, I am curious.
The difference is that with the new @preserved-rebuild the 'old' library
is not deleted until all of the dependent packages have been
successfully rebuilt to use the 'new' library. With the old
revdep-rebuild mechanism, the 'old' library was deleted during the
upgrade emerge. Therefore after the new library was merged, packages
which depended on the old library could not be run until these
dependent packages were rebuilt to use the new library.
 Though any which were running at the time the new library was merged
would continue to run.