Subject: [bug#39414] [PATCH core-updates 0/2] Clarify search path handling in commencement.scm

From: Jan Nieuwenhuizen <[email-masked]>
Date: Thu, 06 Feb 2020 07:39:00 +0100

Ludovic Courtès writes:

Hello Ludo',

> The patch below for current ‘core-updates’ is an attempt to clarify
> search path handling in commencement.scm by:

(Weird, this initial mail got sorted into a new debbugs-submit folder,
only found it later)

>   1. Having ‘native-search-paths’ fields only for compilers—e.g.,
>      “C_INCLUDE_PATH” belongs to the compiler, not to libc.
>
>   2. Avoiding phases that manually fiddle with search path
>      environment variables: normally, this is handled automatically
>      by the ‘set-paths’ phase based on the declared search paths,
>      so manual fiddling should be a last resort and it should be
>      well commented so we remember why it’s there.
>
> This is an attempt to reduce complexity and keep things declarative
> as much as possible.  I’ve tested it on top of
> 46312064de8ae0cca531fddbc4b5ec8421e5d866 and “guix build coreutils”
> succeeds.

Very nice, thank you.  I was happy to get it to build and did not
imagine all this fiddling could actually be workarounds that could
(should!)  all be removed.  Not only will this help readability and
maintenance, it will make porting this to other distributions (NixOS) a
lot easier too.

> There’s another pattern that I found hard to follow that has to do
> with the reuse of build phases.
>
> For example, there’s a build phase named ‘setenv’ (perhaps we should
> find a more descriptive name :-)) in the various GCCs that is reused
> or replaced; when looking at a specific package, it’s difficult to
> see which phases it really runs because this particular phase is
> inherited and modified on several layers.  If I can make time for it,
> I’ll see if I can come up with a proposal to clarify this, but at any
> rate, it’s probably something to keep in mind for future changes.
>
> Thoughts?  (I’m particularly interested in your feedback, janneke!)

Yes, I agree.  A first step could be to use better names and possibly
split it up into serveral stages: set-configure-shells, set-cc-paths?

Doing this will probably only need overriding the set-cc-paths.  I'm not
sure how to make the inherit+replace issue more obvious but it has
been biting me and annoying me too.

Maybe when we get into this replace trickery it is better to not reuse
parent's stages at all

>      (arguments
>       (substitute-keyword-arguments (package-arguments gcc-core-mesboot)

but fully rewrite (arguments ...)?  I haven't looked into the
consequences.  In any case, with patch it has gotten a lot better
already, thank you!

janneke

-- 
Jan Nieuwenhuizen <[email-masked]> | GNU LilyPond http://lilypond.org
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