[bug#37322] [PATCH 1/2] adds the capability of importing a specified version to the crate importer

[Martin Becze <mjbecze@riseup.net>]

---
 guix/import/crate.scm | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/guix/import/crate.scm b/guix/import/crate.scm
index f6057dbf8b..3266ebdfec 100644
--- a/guix/import/crate.scm
+++ b/guix/import/crate.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2016 David Craven <david@craven.ch>
 ;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019 Martin Becze <mjbecze@riseup.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -181,8 +182,8 @@ and LICENSE."
   ;; This regexp matches that.
   (make-regexp "^(.*) OR (.*)$"))
 
-(define (crate->guix-package crate-name)
-  "Fetch the metadata for CRATE-NAME from crates.io, and return the
+(define (crate->guix-package crate-name@version)
+  "Fetch the metadata for CRATE-NAME@VERSION from crates.io, and return the
 `package' s-expression corresponding to that package, or #f on failure."
   (define (string->license string)
     (match (regexp-exec %dual-license-rx string)
@@ -193,13 +194,29 @@ and LICENSE."
   (define (normal-dependency? dependency)
     (eq? (crate-dependency-kind dependency) 'normal))
 
+  (define crate-name-version-list
+    (let ((lnv (string-split crate-name@version #\@)))
+      (if (= 1 (length lnv))
+	  (append lnv '(#f))
+	  lnv)))
+
+  (define crate-name
+    (car crate-name-version-list))
+
+
   (define crate
     (lookup-crate crate-name))
 
+  (define crate-version-string
+    (let ((version (cadr crate-name-version-list)))
+      (if version
+        version
+        (crate-latest-version crate))))
+
   (and crate
        (let* ((version        (find (lambda (version)
                                       (string=? (crate-version-number version)
-                                                (crate-latest-version crate)))
+                                                crate-version-string))
                                     (crate-versions crate)))
               (dependencies   (crate-version-dependencies version))
               (dep-crates     (filter normal-dependency? dependencies))
-- 
2.23.0