scripts: refresh: Add -m manifest option.

* guix/scripts/refresh.scm (%options): Add -m option,
(show-help): document it,
(packages-from-manifest): new procedure,
(guix-refresh): use packages from manifest if specified, otherwise
keep the previous behaviour.
* doc/guix.texi (Invoking guix refresh): document new option.

doc/guix.texi

@@ -5875,6 +5875,11 @@ The @code{non-core} subset refers to the remaining packages.  It is
 typically useful in cases where an update of the core packages would be
 inconvenient.
 
+@item --manifest=@var{file}
+@itemx -m @var{file}
+Select all the packages from the manifest in @var{file}. This is useful to
+check if any packages of the user manifest can be updated.
+
 @item --type=@var{updater}
 @itemx -t @var{updater}
 Select only packages handled by @var{updater} (may be a comma-separated

guix/scripts/refresh.scm

@@ -4,6 +4,7 @@
 ;;; Copyright © 2014 Eric Bavier <bavier@member.fsf.org>
 ;;; Copyright © 2015 Alex Kost <alezost@gmail.com>
 ;;; Copyright © 2016 Ben Woodcroft <donttrustben@gmail.com>
+;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -27,6 +28,7 @@
   #:use-module (guix store)
   #:use-module (guix utils)
   #:use-module (guix packages)
+  #:use-module (guix profiles)
   #:use-module (guix upstream)
   #:use-module (guix discovery)
   #:use-module (guix graph)
@@ -79,6 +81,9 @@
         (option '(#\L "list-updaters") #f #f
                 (lambda args
                   (list-updaters-and-exit)))
+        (option '(#\m "manifest") #t #f
+                (lambda (opt name arg result)
+                  (alist-cons 'manifest arg result)))
         (option '(#\e "expression") #t #f
                 (lambda (opt name arg result)
                   (alist-cons 'expression arg result)))
@@ -125,6 +130,8 @@ specified with `--select'.\n"))
   -s, --select=SUBSET    select all the packages in SUBSET, one of
                          `core' or `non-core'"))
   (display (G_ "
+  -m, --manifest=FILE    select all the packages from the manifest in FILE"))
+  (display (G_ "
   -t, --type=UPDATER,... restrict to updates from the specified updaters
                          (e.g., 'gnu')"))
   (display (G_ "
@@ -306,6 +313,24 @@ dependent packages are rebuilt: ~{~a~^ ~}~%"
                  (map full-name covering))))
       (return #t))))
 
+
+;;;
+;;; Manifest.
+;;;
+
+(define (manifest->packages manifest)
+  "Return the list of packages in MANIFEST."
+  (filter-map (lambda (entry)
+                (let ((item (manifest-entry-item entry)))
+                  (if (package? item) item #f)))
+              (manifest-entries manifest)))
+
+(define (packages-from-manifest manifest)
+  "Return the list of packages in loaded MANIFEST."
+  (let* ((user-module (make-user-module '((guix profiles) (gnu))))
+         (manifest    (load* manifest user-module)))
+    (manifest->packages manifest)))
+
 
 ;;;
 ;;; Entry point.
@@ -378,8 +403,7 @@ update would trigger a complete rebuild."
          ;; the command line.
          (warn?           (or (assoc-ref opts 'argument)
                               (assoc-ref opts 'expression)))
-
+         (args-packages
-         (packages
           (match (filter-map (match-lambda
                                (('argument . spec)
                                 ;; Take either the specified version or the
@@ -400,7 +424,11 @@ update would trigger a complete rebuild."
                                     result))
                               '())))
             (some                                 ; user-specified packages
-             some))))
+             some)))
+         (packages
+          (match (assoc-ref opts 'manifest)
+            (#f args-packages)
+            ((? string? file) (packages-from-manifest file)))))
     (with-error-handling
       (with-store store
         (run-with-store store