bug#41182: Profile hooks ignore system and target

[Mathieu Othacehe <m.othacehe@gmail.com>]

Hey Ludo,

> So I’m very much tempted to instead require each hook to take ‘system’
> and ‘#:target’ arguments and pass them to ‘gexp->derivation’.  It’ll
> break the API, in case someone out there has custom profile hooks
> (unlikely given that it’s not really documented), but I’d say that’s OK.
>
> Thoughts?

What seems strange to me is that gexp->derivation has target set to
'current by default, so it should use the defined target. Now, that I
look at it, it's using "%current-target-system".

Would it make any difference to switch:

--8<---------------cut here---------------start------------->8---
      (target -> (if (eq? target 'current)
                     (%current-target-system)
                     target))
--8<---------------cut here---------------end--------------->8---

to

--8<---------------cut here---------------start------------->8---
(target (if (eq? target 'current)
            (current-target-system)
            (return target)))
--8<---------------cut here---------------end--------------->8---

like for lower-object, gexp->file and gexp->script?

Regarding breaking the profile hooks API, it's fine by me.

Thanks for investigating this,

Mathieu