bug#48682: recursive import between (gnu packages chez) and (gnu packages racket)

[raingloom <raingloom@riseup.net>]

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On Thu, 27 May 2021 00:26:56 -0400
Philip McGrath <philip@philipmcgrath.com> wrote:

> Hi, I've been working on Racket packaging. I haven't looked into this 
> much yet---hopefully I can tomorrow---but here are a few quick
> thoughts.
> 
> On 5/26/21 2:54 PM, raingloom wrote:
>  > I also haven't found any other mention of chez-scheme in racket.scm
>  > other than the line that imports it, which is weird, given that
>  > Racket  
> 
> This was my doing. When I added `(gnu packages racket)` in [1], I 
> adapted the patch from a racket.scm I'd been using to experiment
> ([2], also some branches of [3]): the changes that actually use (gnu
> packages chez) aren't ready to go yet, but apparently I left the
> import line in.
> 
> 
> On 5/26/21 2:54 PM, raingloom wrote:
>  > other than the line that imports it, which is weird, given that
>  > Racket is now built on Chez, so I'd expect it to use it as an
>  > input. I guess it's a bundled version? In any case I don't think I
>  > should just remove the import, because it will be needed
>  > eventually, so this issue needs to be fixed by then.  
> 
> Racket uses a fork of Chez Scheme: I described the situation in [4]. 
> Racket won't have upstream Chez as an input in the foreseeable, but, 
> from a packaging perspective, building Racket's Chez fork uses many
> of the same pieces as building upstream Chez. I think it may make
> sense to refactor out some of the common infrastructure, so both
> `(gnu packages racket)` and `(gnu packages chez)` could depend on
> some low-level module, but I'm not sure what the Guix-preferred way
> to organize things would be. (I'm mostly a Racketeer using Racket
> packaging to learn more about Guix.)
> 
> Here are some ways `(gnu packages chez)` and `(gnu packages racket)`
> are intertwined, in no particular order:
> 
>    - `racket-minimal` should use the `nanopass` and `stex` origins
>       as `chez-scheme` does. (But it would be easiest to do this
>       once I've changed `racket-minimal` to build from the Git source,
>       rather than the bootstrapped tarball: I hope that will be soon.)
>       Some more of my not-quite-current thoughts on that at [5].
> 
>    - The `chez-scheme` phases `unpack-nanopass+stex`, `configure`,
>      `prepare-stex`, and `install-doc` should be shared with Racket.
>      I think it would be better to put them in a build-side module and
>      actually share them, rather than to do tricky things to extract
>      their s-expression representation from
>      `(package-arguments chez-scheme)`. On the other hand, I think a
>      build system would be overkill: it would only build vanilla Chez
>      and Racket-flavored Chez.
> 
>    - Racket-flavored Chez has added some backends that vanilla Chez
>      doesn't support (and can't be readily ported, unless upstream
> Chez eventually adopts Racket's changes to generating backends).
>      In particular, Racket-flavored Chez adds support for threading on
>      ARMv6 and support for aarch64 (which vanilla Chez doesn't
> support at all). I haven't thought at all deeply about this, but it
> might make sense for the default `chez-scheme` package on those
> architectures to be Racket-flavored Chez.
> 
>    - We may in fact want to use Racket to bootstrap vanilla Chez.
> 
>      Chez has the usual problem with self-hosting compilers that you
>      need the old version to compile the new version. Specifically,
> you need "bootfiles", which encapsulate the Scheme-implemented portion
>      of Chez, compiled to machine code. Thus, (a) they are platform-
>      specific and (b) they need to agree precisely with the
> C-implemented part of Chez on the layout of datatypes and such.
> 
>      The vanilla Chez Git repository [6] has bootfiles for i686,
> x86_64, and (non-threaded) ARMv6. Once you've done a native build for
> one of those platforms, you can use it to cross-compile for any
> platform Chez supports (ppc32, various BSDs, etc.). But these are
> binary blobs. From a "trusting trust" perspective, it's especially
> striking if you consider that Chez Scheme was non-free software from
> 1984 to 2016, and the first libre release likewise needed the
> bootfiles of its ancestors. (However, building bootfiles is
> reproducible: Chez in fact builds them twice and errors if they aren't
>      byte-for-byte identical.)
> 
>      But Racket is able to simulate enough of Chez to (slowly)
>      compile the Chez compiler and generate bootfiles, providing a
> path to Chez from just a C compiler. Racket does its whole
> bootstrapping process regularly in CI, and I'm working on getting the
> Guix package to do likewise.
> 
>      Unfortunately, the Racket fork has diverged enough from vanilla
> Chez that the current Racket "cs-bootstrap" package [7] can't build
>      vanilla Chez, but I hope that the solution is just a matter of
>      walking through the Git history to find the right older version
> of the bootstrapping package, before the Racket fork's `#!base-rtd`
>      gained a vector of ancestors rather than a parent and a few such
>      things. But I'd like to be able to build Racket packages with
> Guix before I try that :)
> 
> Ok, that got a bit long.
> 
> I don't know where the cycle came from with `emacs-geiser-racket`,
> but I think it would be reasonable either to do some refactoring to
> `(gnu packages chez)` and `(gnu packages racket)`, or to just remove
> the import for now to un-break things and figure out the rest later.
> 
> -Philip
> 
> [1]: https://issues.guix.gnu.org/47829
> [2]: https://gitlab.com/philip1/guix-racket-experiment
> [3]: https://gitlab.com/philip1/guix-patches/
> [4]: https://issues.guix.gnu.org/46865#3
> [5]: https://issues.guix.gnu.org/47153#2
> [6]: https://github.com/cisco/ChezScheme
> [7]: 
> https://github.com/racket/racket/tree/master/racket/src/ChezScheme/rktboot

Well, here is a quick and obvious fix for now.

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From cef344639ccbf45b5397368d643a36fa48dac098 Mon Sep 17 00:00:00 2001
From: raingloom <raingloom@riseup.net>
Date: Fri, 28 May 2021 03:59:16 +0200
Subject: [PATCH] gnu: Break up import loop between (gnu packages racket) and
 (gnu packages chez).

* gnu/packages/racket.scm: Remove (gnu packages chez) import.
---
 gnu/packages/racket.scm | 2 --
 1 file changed, 2 deletions(-)

diff --git a/gnu/packages/racket.scm b/gnu/packages/racket.scm
index be33270b30..2d606071fe 100644
--- a/gnu/packages/racket.scm
+++ b/gnu/packages/racket.scm
@@ -32,8 +32,6 @@
   #:use-module (ice-9 match)
   #:use-module (gnu packages)
   #:use-module (gnu packages bash)
-  #:use-module ((gnu packages chez)
-                #:select (chez-scheme))
   #:use-module (gnu packages compression)
   #:use-module (gnu packages databases)
   #:use-module (gnu packages fontutils)
-- 
2.31.1