build: julia-build-system: Create 'Project.toml' file when missing.

* guix/build/julia-build-system.scm (link-depot): Create 'Project.toml' file
when missing using data provided by the user.
(julia-create-package-toml): Remove from export.
* doc/guix.texi (Build Systems): Update julia-build-system section.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

doc/guix.texi

@@ -71,7 +71,7 @@ Copyright @copyright{} 2019 Kyle Andrews@*
 Copyright @copyright{} 2019 Alex Griffin@*
 Copyright @copyright{} 2019, 2020, 2021 Guillaume Le Vaillant@*
 Copyright @copyright{} 2020 Liliana Marie Prikler@*
-Copyright @copyright{} 2019, 2020, 2021 Simon Tournier@*
+Copyright @copyright{} 2019, 2020, 2021, 2022 Simon Tournier@*
 Copyright @copyright{} 2020 Wiktor Żelazny@*
 Copyright @copyright{} 2020 Damien Cassou@*
 Copyright @copyright{} 2020 Jakub Kądziołka@*
@@ -8363,9 +8363,10 @@ julia} packages, which essentially is similar to running @samp{julia -e
 @env{JULIA_LOAD_PATH} contains the paths to all Julia package inputs.
 Tests are run by calling @code{/test/runtests.jl}.
 
-The Julia package name is read from the file @file{Project.toml}.  This
-value can be overridden by passing the argument @code{#:julia-package-name}
-(which must be correctly capitalized).
+The Julia package name and uuid is read from the file
+@file{Project.toml}.  These values can be overridden by passing the
+argument @code{#:julia-package-name} (which must be correctly
+capitalized) or @code{#:julia-package-uuid}.
 
 Julia packages usually manage their binary dependencies via
 @code{JLLWrappers.jl}, a Julia package that creates a module (named
@@ -8393,12 +8394,10 @@ MbedTLS package:
               (find-files "src/wrappers/" "\\.jl$"))))
 @end lisp
 
-Some older packages that aren't using @file{Package.toml} yet, will require
-this file to be created, too.  The function @code{julia-create-package-toml}
-helps creating the file.  You need to pass the outputs and the source of the
-package, its name (the same as the @code{file-name} parameter), the package
-uuid, the package version, and a list of dependencies specified by their name
-and their uuid.
+Some older packages that aren't using @file{Project.toml} yet, will
+require this file to be created, too.  It is internally done if the
+arguments @code{#:julia-package-name} and @code{#:julia-package-uuid}
+are provided.
 @end defvr
 
 @defvr {Scheme Variable} maven-build-system

guix/build/julia-build-system.scm

@@ -1,7 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2019, 2020 Nicolò Balzarotti <nicolo@nixo.xyz>
 ;;; Copyright © 2021 Jean-Baptiste Volatier <jbv@pm.me>
-;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2021, 2022 Simon Tournier <zimon.toutoune@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -27,8 +27,8 @@
   #:use-module (ice-9 regex)
   #:use-module (ice-9 rdelim)
   #:use-module (ice-9 popen)
+  #:use-module (srfi srfi-1)
   #:export (%standard-phases
-            julia-create-package-toml
             julia-build))
 
 ;; Commentary:
@@ -138,6 +138,8 @@ Project.toml)."
 (define* (link-depot #:key source inputs outputs
                      julia-package-name julia-package-uuid  #:allow-other-keys)
   (let* ((out (assoc-ref outputs "out"))
+         (name+version (strip-store-file-name out))
+         (version (last (string-split name+version #\-)))
          (package-name (or
                         julia-package-name
                         (project.toml->name "Project.toml")))
@@ -148,6 +150,14 @@ Project.toml)."
 println(Base.version_slug(Base.UUID(\"~a\"),
                           Base.SHA1(Pkg.GitTools.tree_hash(\".\"))))" uuid)))
          (slug (string-trim-right (get-string-all pipe))))
+    ;; Few packages do not have the regular Project.toml file, then when they
+    ;; are propagated, dependencies do not find them and an raise error.
+    (unless (file-exists? "Project.toml")
+        (julia-create-package-toml (getcwd)
+                                   julia-package-name julia-package-uuid
+                                   version
+                                   #:file "Project.toml"))
+
     ;; When installing a package, julia looks first at in the JULIA_DEPOT_PATH
     ;; for a path like packages/PACKAGE/XXXX
     ;; Where XXXX is a slug encoding the package UUID and SHA1 of the files
@@ -157,17 +167,16 @@ println(Base.version_slug(Base.UUID(\"~a\"),
     (symlink package-dir (string-append out "/share/julia/packages/"
                                         package-name "/" slug))))
 
-(define (julia-create-package-toml outputs source
-                                   name uuid version
-                                   deps)
-  "Some packages are not using the new Package.toml dependency specifications.
-Write this file manually, so that Julia can find its dependencies."
+(define* (julia-create-package-toml location
+                                    name uuid version
+                                    #:optional
+                                    (deps '())
+                                    #:key
+                                    (file "Project.toml"))
+  "Some packages are not using the new Project.toml dependency specifications.
+Write this FILE manually, so that Julia can find its dependencies."
   (let ((f (open-file
-            (string-append
-             (assoc-ref outputs "out")
-             %package-path
-             (string-append
-              name "/Project.toml"))
+            (string-append location "/" file)
             "w")))
     (display (string-append
               "