pack: Honor package transformation options.

Previously they would silently be ignored.

* guix/scripts/pack.scm (guix-pack)[manifest-from-args]: Add 'store'
parameter.  Call 'options->transformation' and use it.
Move 'with-store' and 'parameterize' around the 'let'.
* tests/guix-pack.sh: Add test using '--with-source'.

guix/scripts/pack.scm

@@ -43,6 +43,7 @@ (define-module (guix scripts pack)
   #:autoload   (gnu packages guile) (guile2.0-json guile-json)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-37)
   #:use-module (ice-9 match)
   #:export (compressor?
@@ -397,8 +398,13 @@ (define maybe-package-argument
        (read/eval-package-expression exp))
       (x #f)))
 
-  (define (manifest-from-args opts)
+  (define (manifest-from-args store opts)
-    (let ((packages      (filter-map maybe-package-argument opts))
+    (let* ((transform     (options->transformation opts))
+           (packages      (map (match-lambda
+                                 (((? package? package) output)
+                                  (list (transform store package)
+                                        output)))
+                               (filter-map maybe-package-argument opts)))
            (manifest-file (assoc-ref opts 'manifest)))
       (cond
        ((and manifest-file (not (null? packages)))
@@ -409,8 +415,16 @@ (define (manifest-from-args opts)
        (else (packages->manifest packages)))))
 
   (with-error-handling
+    (with-store store
+      (parameterize ((%graft? (assoc-ref opts 'graft?))
+                     (%guile-for-build (package-derivation
+                                        store
+                                        (if (assoc-ref opts 'bootstrap?)
+                                            %bootstrap-guile
+                                            (canonical-package guile-2.2))
+                                        #:graft? (assoc-ref opts 'graft?))))
         (let* ((dry-run?    (assoc-ref opts 'dry-run?))
-           (manifest    (manifest-from-args opts))
+               (manifest    (manifest-from-args store opts))
                (pack-format (assoc-ref opts 'format))
                (name        (string-append (symbol->string pack-format)
                                            "-pack"))
@@ -429,13 +443,6 @@ (define (manifest-from-args opts)
                                (leave (G_ "~a: unknown pack format")
                                       format))))
                (localstatedir? (assoc-ref opts 'localstatedir?)))
-      (with-store store
-        (parameterize ((%graft? (assoc-ref opts 'graft?))
-                       (%guile-for-build (package-derivation
-                                          store
-                                          (if (assoc-ref opts 'bootstrap?)
-                                              %bootstrap-guile
-                                              (canonical-package guile-2.2)))))
           ;; Set the build options before we do anything else.
           (set-build-options-from-command-line store opts)
 

tests/guix-pack.sh

@@ -83,3 +83,10 @@ guix pack --dry-run --bootstrap -f docker -S /opt/gnu=/ guile-bootstrap
 # Build a tarball pack of cross-compiled software.  Use coreutils because
 # guile-bootstrap is not intended to be cross-compiled.
 guix pack --dry-run --bootstrap --target=arm-unknown-linux-gnueabihf coreutils
+
+# Make sure package transformation options are honored.
+mkdir -p "$test_directory"
+drv1="`guix pack -n guile 2>&1 | grep pack.*\.drv`"
+drv2="`guix pack -n --with-source=guile=$test_directory guile 2>&1 | grep pack.*\.drv`"
+test -n "$drv1"
+test "$drv1" != "$drv2"