post_upgrade() {
    local breakpoints=(
        2.9.0-1
        2.12.0-1
    )

    for v in "${breakpoints[@]}"; do
        if [[ $(vercmp "$v" "$2") -ne "-1" ]]; then
            "_${v//[.-]/_}_changes"
        fi
    done
}

_2_9_0_1_changes() {
    cat << EOF
It was found that there was an upgrade from old devtools package to the new one, which requires manual intervention:

* make sure that devtools are upgraded to the latest release;
* merge upstream configuration into local configuration (e.g. by using pacdiff);
* run setup command (i.e. ahriman service-setup) with the same arguments as did before;
* remove build chroot, e.g.: ahriman service-clean --chroot;
* update local databases: ahriman update --no-aur --no-local --no-manual -yy.

For more information kindly refer to migration notes https://ahriman.readthedocs.io/en/stable/migration.html.
EOF
}

_2_12_0_1_changes() {
    cat << EOF
Whereas old local tree is still supported it is highly recommended to migrate to the new one:

* stop and disable all services;
* run service-tree-migrate as ahriman user;
* edit local configuration to avoid pointing to the old paths;
* run setup command (i.e. ahriman service-setup) with the same arguments as did before;
* update remote services in order to support new paths (or setup redirects) if any;
* enable web and timer services again by using x86_64-aur-clone suffix,
  where x86_64 is the repository architecture and aur-clone is the repository name.

For more information kindly refer to migration notes https://ahriman.readthedocs.io/en/stable/migration.html.
EOF
}