Bug 787755 – sys-apps/portage: emerge option to recursively remove a package and its reverse dependencies

• Product: Portage Development
• Status: CONFIRMED ---

[Description Zac Medico 2021-05-02 18:18:02 UTC]

An option to recursively remove a package and its reverse dependencies will complement the related option requested in bug 416907. It's possible to achieve an equivalent result by using emerge --deselect <packages> && emerge --depclean, but we need an automated way to determine the recursive reverse dependencies in the emerge --deselect <packages> list, and we don't want to invoke the global emerge --depclean command.

[Comment 1 Zac Medico 2021-05-02 18:45:32 UTC]

This calculation is useful for various conflict resolution strategies, since it can be used to actively eliminate packages with conflicting or unsatisfiable dependencies. It can possibly be adapted as a means to automatically constrain the scope of emerge --keep-going calculations to fit the behavior described in bug 476350.

[Comment 2 Zac Medico 2021-05-02 18:54:05 UTC]

Since emerge --depclean already builds a suitable dependency graph for this calculation, it's just a matter of performing the graph operations to determine which packages would have to be deselected, which should only be a few lines of code if expressed well.

[Comment 3 Zac Medico 2021-05-02 19:00:47 UTC]

Simply traverse graph edges from the packages that we would like to remove, and use the PackageSet iterAtomsForPackage method to pair edges with matching @selected atoms that need to be deselected.