Re: Package input loop detection

["Gábor Boskovits" <boskovits@gmail.com>]

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2018-02-12 16:30 GMT+01:00 Ricardo Wurmus <rekado@elephly.net>:

>
> Hi,
>
> > I've had this issue for a while now, while adding some packages, I'll
> > create a loop in the package graph, which causes Guix to just loop
> > infinitely when trying to generate derivations.
>
> this is a great initiative.  I’ve been having this issue in the past as
> well, and I’d really like Guix to be a little smarter about it.
>
>
I also welcome this idea.


> > I'm not particularly fond of the implementation, because the
> > package-derivation function is called from expand-input called from
> > bag->derivation, the information about the part of the graph that has
> > been traversed is passed through each function.
> >
> > The seen-package-list argument could be removed, but the ordering
> > information is really useful when printing out the error message. I
> > think it should be still possible to generate this after finding the
> > issue by searching through the graph of packages, which would allow
> > removing this one argument.
> >
> > One other thought I had is that this could be extracted to something in
> > guix lint, which would at least allow finding these problems, without
> > touching the core derivation related code.
>
> I’d be in favour of keeping it out of the core and stash it away in a
> separate tool.  Not sure if that should be “guix lint” (what about “guix
> graph”?), but I would prefer that over having the code run all the time.
>
>
I feel that "guix graph" is a good suggestion.
Correct me if I'm mistaken, but it seems to me that we currently traverse
our graph breadth first. For this functionality a depth first traversal
would have
benefits. Could be extended to topologically short the whole DAG. WDYT?


> --
> Ricardo
>
> GPG: BCA6 89B6 3655 3801 C3C6  2150 197A 5888 235F ACAC
> https://elephly.net
>
>
>
>

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