[bug#56618] [PATCH 0/2] Let 'guix gc -d' delete old Home generations

[Maxim Cournoyer]

Hi Ludo,

Ludovic Courtès <ludo@gnu.org> writes:

> Hi,
>
> Andrew Tropin <andrew@trop.in> skribis:
>
>> BTW, a little offtopic (related to gc, but not related to these changes)
>> problem I have, which is very annoying: After guix gc, guix home
>> rebuilds/redownloads a lot of stuff.  The configuration and channels are
>> absolutely the same.
>>
>> guix home reconfigure home-configs.scm # builds/downloads a lot of stuff
>> guix gc
>> guix home reconfigure home-configs.scm # do everything again
>>
>> Am I missing something and it is expected behavior or is it a bug?
>
> It’s an expected annoyance: to determine whether a graft needs to be
> applied, we first need to download/build the ungrafted variant, which is
> why you’re seeing this (this is worsened by the fact that many packages
> are candidates for grafting currently on ‘master’).

A perhaps naive idea: could we register GC roots for the ungrafted
variant when grafted?  To avoid having to fetch it anew following 'guix
gc' ?

Thanks,

Maxim