bug#42053: hidden derivation build with inferiors

["Ludovic Courtès" <ludo@gnu.org>]

Ludovic Courtès <ludo@gnu.org> skribis:

> Julien Lepiller <julien@lepiller.eu> skribis:
>
>> someone (kernel-help) on IRC today was having issues using an inferior
>> kernel with their os configuration and reported that guix was
>> "hanging". It turns out that guix was actually building the kernel in
>> the background, but did not report anything to the user. kernel-help
>> was kind enough to share their config, and I can confirm that guix is
>> building the kernel, but doesn't tell anything.
>
> Aaah right.  What happens here is that grafts lead the inferior to start
> building the kernel (this is expected).  However, ‘proxy’ in (guix
> inferior) doesn’t forward build output to ‘current-build-output-port’.
> That’s why there’s no message saying what’s being built, no spinner, etc.
>
> I’ll see what can be done.

Not surprisingly, to fix it, we need to implement a proxy that
interprets all the messages exchanged so that it can write to
‘current-build-output-port’ when appropriate (that’s the usual
all-or-nothing problem with proxies.)

For the daemon rewrite in Scheme, we’ll need to have server stubs
anyway, so perhaps that’s an opportunity to fiddle with that.  Caleb?

Ludo’.