A "worse" choice is picked when resolving transaction

[vmojzis]

Hi, I've encountered a situation where a transaction can be resolved in two ways and libsolv picks the one that is in some sense worse.
I understand that both are valid, but is there something that could be done to prefer the other choice without breaking other use cases?

The situation is following:

• yolo requires (yolo-selinux if selinux-policy-targeted)
• selinux-policy requires selinux-policy-base
• selinux-policy-base is provided by selinux-policy-targeted and selinux-policy-mls
• selinux-policy is a protected package

Installed packages:

• selinux-policy
• selinux-policy-targeted
• selinux-policy-mls
• yolo
• yolo-selinux

When removing yolo-selinux, there are two options how to resolve it:

1. remove yolo and yolo-selinux
2. remove yolo-selinux and selinux-policy-targeted

From the user perspective, the first option is preferred, because yolo is designed to work with yolo-selinux and removing selinux-policy-targeted disables SELinux. However libsolv chooses the second option. We cannot mark selinux-policy-targeted as protected, because a small number of users use selinux-policy-mls instead. Is there a way to let libsolv know that selinux-policy-targeted should be treated as protected based on a configuration file?

[mlschroe]

I don't think there's currently a way to make libsolv choose yolo over selinux-policy-targeted. Libsolv should IMHO take the weak dependencies into consideration when deciding which package to remove in "allowuninstall" mode, but it currently just uses the first problem package. See solver_autouninstall in problems.c for the gory details.