Subject: bug#16762: Installed packages are not considered part of the archive contents

From: Dmitry Gutov <[email-masked]>
Date: Mon, 24 Mar 2014 08:20:48 +0200

On 24.03.2014 02:55, Stefan wrote:

> Does it affect the output of M-x package-list RET?

It's identical (checked with diff).

> What about the package-menu-mark-upgrades?

It works. Don't see any problems.

> If we can keep the already installed packages, couldn't we also keep the
> already built-in packages?

Yes, seems so. I hadn't tried this before because the previous behavior 
was to omit them (I think), but the patch below seems to work fine WRT 
the questions above.

=== modified file 'lisp/emacs-lisp/package.el'
--- lisp/emacs-lisp/package.el	2014-03-23 08:35:56 +0000
+++ lisp/emacs-lisp/package.el	2014-03-24 06:11:52 +0000
@@ -1047,14 +1047,9 @@
           (existing-packages (assq name package-archive-contents))
           (pinned-to-archive (assoc name package-pinned-packages)))
      (cond
-     ;; Skip entirely if pinned to another archive or already installed.
-     ((or (and pinned-to-archive
-               (not (equal (cdr pinned-to-archive) archive)))
-          (let ((bi (assq name package--builtin-versions)))
-            (and bi (version-list-= version (cdr bi))))
-          (let ((ins (cdr (assq name package-alist))))
-            (and ins (version-list-= version
-                                     (package-desc-version (car ins))))))
+     ;; Skip entirely if pinned to another archive.
+     ((and pinned-to-archive
+           (not (equal (cdr pinned-to-archive) archive)))
        nil)
       ((not existing-packages)
        (push (list name pkg-desc) package-archive-contents))
@@ -1090,8 +1085,11 @@
         (package-refresh-contents))
       (list (intern (completing-read
                      "Install package: "
-                    (mapcar (lambda (elt) (symbol-name (car elt)))
-                            package-archive-contents)
+                    (delq nil
+                          (mapcar (lambda (elt)
+                                    (unless (package-installed-p (car elt))
+                                      (symbol-name (car elt))))
+                                  package-archive-contents))
                      nil t)))))
    (package-download-transaction
     (if (package-desc-p pkg)