import: utils: 'recursive-import' returns packages in topological order.

* guix/import/utils.scm (topological-sort): New procedure.
(recursive-import): Rewrite to use it.
* tests/import-utils.scm ("recursive-import"): New test.
* guix/import/cran.scm (cran->guix-package): Always return two values.
* guix/scripts/import/cran.scm (guix-import-cran): Remove 'reverse' call
on 'cran-recursive-import' result.
* guix/scripts/import/crate.scm (guix-import-crate): Likewise.
* guix/scripts/import/elpa.scm (guix-import-elpa): Likewise.
* guix/scripts/import/gem.scm (guix-import-gem): Likewise.
* guix/scripts/import/hackage.scm (guix-import-hackage): Likewise.
* guix/scripts/import/opam.scm (guix-import-opam): Likewise.
* guix/scripts/import/pypi.scm (guix-import-pypi): Likewise.
* guix/scripts/import/stackage.scm (guix-import-stackage): Likewise.
* tests/gem.scm ("gem-recursive-import"): Change the order of package
expressions accordingly.

2 files changed, 35 insertions, 12 deletions

diff --git a/tests/gem.scm b/tests/gem.scm
index a12edb294c..82b2c3cea1 100644
--- a/tests/gem.scm
+++ b/tests/gem.scm
@@ -123,22 +123,21 @@
              (_ (error "Unexpected URL: " url)))))
         (match (stream->list (gem-recursive-import "foo"))
           ((('package
-              ('name "ruby-foo")
+              ('name "ruby-bar")
               ('version "1.0.0")
               ('source
                ('origin
                  ('method 'url-fetch)
-                 ('uri ('rubygems-uri "foo" 'version))
+                 ('uri ('rubygems-uri "bar" 'version))
                  ('sha256
                   ('base32
                    "1a270mlajhrmpqbhxcqjqypnvgrq4pgixpv3w9gwp1wrrapnwrzk"))))
               ('build-system 'ruby-build-system)
               ('propagated-inputs
                ('quasiquote
-                (("bundler" ('unquote 'bundler))
-                 ("ruby-bar" ('unquote 'ruby-bar)))))
-              ('synopsis "A cool gem")
-              ('description "This package provides a cool gem")
+                (('"bundler" ('unquote 'bundler)))))
+              ('synopsis "Another cool gem")
+              ('description "Another cool gem")
               ('home-page "https://example.com")
               ('license ('list 'license:expat 'license:asl2.0)))
             ('package
@@ -157,21 +156,22 @@
               ('home-page "https://bundler.io/")
               ('license 'license:expat))
             ('package
-              ('name "ruby-bar")
+              ('name "ruby-foo")
               ('version "1.0.0")
               ('source
                ('origin
                  ('method 'url-fetch)
-                 ('uri ('rubygems-uri "bar" 'version))
+                 ('uri ('rubygems-uri "foo" 'version))
                  ('sha256
                   ('base32
                    "1a270mlajhrmpqbhxcqjqypnvgrq4pgixpv3w9gwp1wrrapnwrzk"))))
               ('build-system 'ruby-build-system)
               ('propagated-inputs
                ('quasiquote
-                (('"bundler" ('unquote 'bundler)))))
-              ('synopsis "Another cool gem")
-              ('description "Another cool gem")
+                (("bundler" ('unquote 'bundler))
+                 ("ruby-bar" ('unquote 'ruby-bar)))))
+              ('synopsis "A cool gem")
+              ('description "This package provides a cool gem")
               ('home-page "https://example.com")
               ('license ('list 'license:expat 'license:asl2.0))))
            #t)
diff --git a/tests/import-utils.scm b/tests/import-utils.scm
index c3ab25d788..3400433bbb 100644
--- a/tests/import-utils.scm
+++ b/tests/import-utils.scm
@@ -24,7 +24,9 @@
   #:use-module (guix packages)
   #:use-module (guix build-system)
   #:use-module (gnu packages)
-  #:use-module (srfi srfi-64))
+  #:use-module (srfi srfi-41)
+  #:use-module (srfi srfi-64)
+  #:use-module (ice-9 match))
 
 (test-begin "import-utils")
 
@@ -41,6 +43,27 @@
   'license:lgpl2.0
   (license->symbol license:lgpl2.0))
 
+(test-equal "recursive-import"
+  '((package                         ;package expressions in topological order
+      (name "bar"))
+    (package
+      (name "foo")
+      (inputs `(("bar" ,bar)))))
+  (stream->list
+   (recursive-import "foo" 'repo
+                     #:repo->guix-package
+                     (match-lambda*
+                       (("foo" 'repo)
+                        (values '(package
+                                   (name "foo")
+                                   (inputs `(("bar" ,bar))))
+                                '("bar")))
+                       (("bar" 'repo)
+                        (values '(package
+                                   (name "bar"))
+                                '())))
+                     #:guix-name identity)))
+
 (test-assert "alist->package with simple source"
   (let* ((meta '(("name" . "hello")
                  ("version" . "2.10")