gexp: 'gexp-modules' now consistently deletes duplicates.

Fixes <https://bugs.gnu.org/32966>.
Reported by Clément Lassieur <clement@lassieur.org>.

* guix/gexp.scm (gexp-attribute): Add 'equal?' optional parameter; pass
it to 'delete-duplicates'.
(gexp-modules)[module=?]: New procedure.
Pass it to 'gexp-attribute'.
* tests/gexp.scm ("gexp-modules deletes duplicates"): New test.

1 files changed, 16 insertions, 0 deletions

diff --git a/tests/gexp.scm b/tests/gexp.scm
index 813ea2ff6f..467370f8cb 100644
--- a/tests/gexp.scm
+++ b/tests/gexp.scm
@@ -680,6 +680,22 @@
    #~(foo #$@(list (with-imported-modules '((foo)) #~+)
                    (with-imported-modules '((bar)) #~-)))))
 
+(test-assert "gexp-modules deletes duplicates"   ;<https://bugs.gnu.org/32966>
+  (let ((make-file (lambda ()
+                     ;; Use 'eval' to make sure we get an object that's not
+                     ;; 'eq?' nor 'equal?' due to the closures it embeds.
+                     (eval '(scheme-file "bar.scm" #~(define-module (bar)))
+                           (current-module)))))
+    (define result
+      ((@@ (guix gexp) gexp-modules)
+       (with-imported-modules `(((bar) => ,(make-file))
+                                ((bar) => ,(make-file))
+                                (foo) (foo))
+         #~+)))
+
+    (match result
+      (((('bar) '=> (? scheme-file?)) ('foo)) #t))))
+
 (test-equal "gexp-modules and literal Scheme object"
   '()
   (gexp-modules #t))