[bug#51838] [PATCH v5 07/45] guix: node-build-system: Add #:absent-dependencies argument.

[Philip McGrath]

* guix/build-system/node.scm (lower, node-build): Add optional
argument #:absent-dependencies with default of ''(). Pass it on
to the build-side code.
* guix/build/node-build-system.scm (patch-dependencies): Respect
the #:absent-dependencies argument, removing specified npm
packages from the "dependencies" or "devDependencies" tables
in "package.json".
---
 guix/build-system/node.scm       | 19 ++++++++++++++++++-
 guix/build/node-build-system.scm |  7 +++++--
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/guix/build-system/node.scm b/guix/build-system/node.scm
index 735f8dd06e..330d10dca5 100644
--- a/guix/build-system/node.scm
+++ b/guix/build-system/node.scm
@@ -47,6 +47,7 @@ (define (default-node)
 (define* (lower name
                 #:key source inputs native-inputs outputs system target
                 (node (default-node))
+                (absent-dependencies ''())
                 #:allow-other-keys
                 #:rest arguments)
   "Return a bag for NAME."
@@ -77,6 +78,7 @@ (define* (node-build name inputs
                      (test-target "test")
                      (tests? #t)
                      (phases '%standard-phases)
+                     (absent-dependencies ''())
                      (outputs '("out"))
                      (search-paths '())
                      (system (%current-system))
@@ -84,7 +86,21 @@ (define* (node-build name inputs
                      (imported-modules %node-build-system-modules)
                      (modules '((guix build node-build-system)
                                 (guix build utils))))
-  "Build SOURCE using NODE and INPUTS."
+  "Build SOURCE using NODE and INPUTS.
+
+The builder will remove Node.js packages listed in ABSENT-DEPENCENCIES from
+the 'package.json' file's 'dependencies' and 'devDependencies' tables.  This
+mechanism can be used both avoid dependencies we don't want (e.g. optional
+features that would increase closure size) and to work around dependencies
+that haven't been packaged for Guix yet (e.g. test utilities)."
+  ;; Before #:absent-dependencies existed, this scenario was often handled by
+  ;; deleting the 'configure phase. Using #:absent-dependencies, instead,
+  ;; retains the check that no dependencies are silently missing and other
+  ;; actions performed by 'npm install', such as building native
+  ;; addons. Having an explicit list of absent dependencies in the package
+  ;; definition should also facilitate future maintenence: for example, if we
+  ;; add a package for a test framework, it should be easy to find all the
+  ;; other packages that use it and enable their tests.
   (define builder
     (with-imported-modules imported-modules
       #~(begin
@@ -96,6 +112,7 @@ (define builder
                       #:test-target #$test-target
                       #:tests? #$tests?
                       #:phases #$phases
+                      #:absent-dependencies #$absent-dependencies
                       #:outputs #$(outputs->gexp outputs)
                       #:search-paths '#$(sexp->gexp
                                          (map search-path-specification->sexp
diff --git a/guix/build/node-build-system.scm b/guix/build/node-build-system.scm
index b74e593838..892104b6d2 100644
--- a/guix/build/node-build-system.scm
+++ b/guix/build/node-build-system.scm
@@ -69,7 +69,8 @@ (define (list-modules directory)
               input-paths)
     index))
 
-(define* (patch-dependencies #:key inputs #:allow-other-keys)
+(define* (patch-dependencies #:key inputs absent-dependencies
+                             #:allow-other-keys)
 
   (define index (index-modules (map cdr inputs)))
 
@@ -86,7 +87,9 @@ (define (resolve-dependencies meta-alist meta-key)
       (('@ . orig-deps)
        (fold (match-lambda*
                (((key . value) acc)
-                (acons key (hash-ref index key value) acc)))
+                (if (member key absent-dependencies)
+                    acc
+                    (acons key (hash-ref index key value) acc))))
              '()
              orig-deps))))
 
-- 
2.32.0