Re: core-updates: Emacs is only supported on x86_64-linux?

[Chris Marusich <cmmarusich@gmail.com>]

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Chris Marusich <cmmarusich@gmail.com> writes:

> How about a patch like the following - would it be acceptable to you?

Actually, I've realized that that patch wasn't quite right.  I've
attached a corrected version to this email.

Although the %current-system parameter will look like "x86_64-linux"
because it's a Guix system name, the %current-target-system parameter
will look like "x86_64-linux-gnu" (or whatever the user happens to
supply, e.g. via the --target option of "guix build") because it's a GNU
triplet.  The attached patch accomplishes the same goal as before, but
it uses string-prefix? to check whether we're building for an x86_64
machine, rather than matching on an exact string.

-- 
Chris

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From 0eb5583f243a399293ae52a3e78ccf7d3a153a47 Mon Sep 17 00:00:00 2001
From: Chris Marusich <cmmarusich@gmail.com>
Date: Mon, 8 Mar 2021 23:13:39 -0800
Subject: [PATCH] gnu: Restore emacs' supported systems.

Recently, librsvg was updated to depend upon rust.  That change inadvertently
restricted the "supported" systems of emacs (among other package) to
x86_64-linux only, since that is the only system declared in the rust
package's list of supported systems.  This unintentionally made emacs
unavailable on all other systems.

This change fixes that by removing the rust dependency from some packages.
The packages remain unchanged from the perspective of an x86_64-linux system,
but from the perspective of other systems, the packages are now supported
again (albeit without certain optional SVG features).

* gnu/packages/gtk.scm (gtk+, gtk+-2)[propagated-inputs]: If compiling for
x86_64, use gdk-pixbuf+svg as the "gdk-pixbuf" input, as usual.  Otherwise,
use gdk-pixbuf, which avoids adding librsvg (thus rust) to the closure of
inputs.  Note that both gtk+ and gtk+-2 are in the transitive closure of
inputs of emacs, so these two changes are necessary.
* gnu/packages/emacs (emacs)[inputs]: If compiling for x86_64, add librsvg to
the inputs, as usual.  Otherwise, do not add it, which avoids adding rust to
the closure of inputs.
---
 gnu/packages/emacs.scm |  8 +++++++-
 gnu/packages/gtk.scm   | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/gnu/packages/emacs.scm b/gnu/packages/emacs.scm
index 98061c93ae0..fe5b3b25b3d 100644
--- a/gnu/packages/emacs.scm
+++ b/gnu/packages/emacs.scm
@@ -71,6 +71,7 @@
   #:use-module (gnu packages xml)
   #:use-module (gnu packages xorg)
   #:use-module (guix utils)
+  #:use-module (ice-9 match)
   #:use-module (srfi srfi-1))
 
 (define-public emacs
@@ -236,7 +237,12 @@
        ("libpng" ,libpng)
        ("zlib" ,zlib)
 
-       ("librsvg" ,librsvg)
+       ;; librsvg is an optional dependency that pulls in rust.  Rust is not
+       ;; supported well on every architecture yet.
+       ,@(if (string-prefix? "x86_64" (or (%current-target-system)
+                                          (%current-system)))
+             `(("librsvg" ,librsvg))
+             '())
        ("libxpm" ,libxpm)
        ("libxml2" ,libxml2)
        ("libice" ,libice)
diff --git a/gnu/packages/gtk.scm b/gnu/packages/gtk.scm
index f458366fb6a..d396425d9a6 100644
--- a/gnu/packages/gtk.scm
+++ b/gnu/packages/gtk.scm
@@ -776,7 +776,12 @@ is part of the GNOME accessibility project.")
    (outputs '("out" "bin" "doc"))
    (propagated-inputs
     `(("atk" ,atk)
-      ("gdk-pixbuf" ,gdk-pixbuf+svg)
+      ;; SVG support is optional and requires librsvg, which pulls in rust.
+      ;; Rust is not supported well on every architecture yet.
+      ("gdk-pixbuf" ,(if (string-prefix? "x86_64" (or (%current-target-system)
+                                                      (%current-system)))
+                         gdk-pixbuf+svg
+                         gdk-pixbuf))
       ("pango" ,pango)))
    (inputs
     `(("cups" ,cups)
@@ -843,7 +848,12 @@ application suites.")
    (propagated-inputs
     `(("at-spi2-atk" ,at-spi2-atk)
       ("atk" ,atk)
-      ("gdk-pixbuf" ,gdk-pixbuf+svg)
+      ;; SVG support is optional and requires librsvg, which pulls in rust.
+      ;; Rust is not supported well on every architecture yet.
+      ("gdk-pixbuf" ,(if (string-prefix? "x86_64" (or (%current-target-system)
+                                                      (%current-system)))
+                         gdk-pixbuf+svg
+                         gdk-pixbuf))
       ("libepoxy" ,libepoxy)
       ("libxcursor" ,libxcursor)
       ("libxi" ,libxi)
-- 
2.26.2


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