[bug#51948] [PATCH] Meson needs proper wrapping

[Vivien Kraus via Guix-patches via <guix-patches@gnu.org>]

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Ludovic Courtès <ludo@gnu.org> writes:
> Vivien Kraus <vivien@planete-kraus.eu> skribis:
>> Meson needs to be wrapped, but the wrapping must not execute a new
>> process, if I understand correctly. I could use wrap-script, but I think
>> it’s more pythonic to set the path through sys.path rather than setting
>> an environment variable.
>
> Isn’t that what ‘wrap-script’ does?
I think wrap-script converts the python script to a guile script that
happens to be the same file as the python script. I realize it won’t
even insert python code in the final program, so the wrapping code won’t
be executed when the python module is loaded by the python interpreter.

> How about providing a user-facing ‘meson’ package that incorporates this
> fix, while keeping the other ‘meson’ packages unchanged, to avoid
> rebuilding too much?  This can be achieved by marking the other packages
> as hidden.
I pushed an update that does precisely that. Is the name "meson-wrapped"
OK? Also, how can I influence guix to rather install the wrapped version
when the user invokes "guix install meson"?

> Could you check ‘guix gc --references meson’ to make sure it does not
> capture too much?  (GUIX_PYTHONPATH might contain references to
> build-time dependencies.)

I see, the only thing to wrap is just the "out" output in fact.


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From dcb7114ada82da073adbbfbeef929a9daa558ccb Mon Sep 17 00:00:00 2001
From: Vivien Kraus <vivien@planete-kraus.eu>
Date: Thu, 18 Nov 2021 15:17:52 +0100
Subject: [PATCH] gnu: meson: Extend the python path in the installed program.

* gnu/packages/build-tools.scm (meson-wrapped): New variable.
---
 gnu/packages/build-tools.scm | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/gnu/packages/build-tools.scm b/gnu/packages/build-tools.scm
index 849101c2a4..f323b6a388 100644
--- a/gnu/packages/build-tools.scm
+++ b/gnu/packages/build-tools.scm
@@ -297,6 +297,28 @@ (define-public meson
 resembles Python.")
     (license license:asl2.0)))
 
+(define-public meson-wrapped
+  (package/inherit meson
+    (arguments
+     `(;; FIXME: Tests require many additional inputs and patching many
+       ;; hard-coded file system locations in "run_unittests.py".
+       #:tests? #f
+       #:phases (modify-phases %standard-phases
+                  ;; Meson calls the various executables in out/bin through the
+                  ;; Python interpreter, so we cannot use the shell wrapper.
+                  (replace 'wrap
+                    (lambda* (#:key outputs inputs #:allow-other-keys)
+                      (let ((python-version
+                             (python-version (assoc-ref inputs "python")))
+                            (output (assoc-ref outputs "out")))
+                        (substitute* (string-append output "/bin/meson")
+                          (("# EASY-INSTALL-ENTRY-SCRIPT")
+                           (format #f "\
+import sys
+sys.path.insert(0, '~a/lib/python~a/site-packages')
+# EASY-INSTALL-ENTRY-SCRIPT"
+                                   output python-version)))))))))))
+
 ;;; This older Meson variant is kept for now for gtkmm and others that may
 ;;; have problems with 0.60.
 (define-public meson-0.59
-- 
2.34.0


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Vivien

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