* lisp/emacs-lisp/package.el: New "external" package status

An external package is any installed package that's not built-in
and not from `package-user-dir', which usually means it's from an
entry in `package-directory-list'.  They are treated much like
built-in packages, in that they cannot be through the Package Menu
deleted and are not considered for upgrades.

(package-desc-status): Identify if a package is installed outside
`package-user-dir'.
(package-menu--print-info-simple)
(package-menu--status-predicate): Add support for it.

* etc/NEWS: Document it.

2 files changed, 17 insertions, 1 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 3ab1f4b963d..48c3a2a5d2e 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -255,6 +255,17 @@ by default at least in Debian, for security reasons).
 
 ** package.el
 
+*** New "external" package status.
+An external package is any installed package that's not built-in and
+not from `package-user-dir', which usually means it's from an entry in
+`package-directory-list'.  They are treated much like built-in
+packages, in that they cannot be through the Package Menu deleted and
+are not considered for upgrades.
+
+The effect, is that a user can manually place a specific version of a
+package inside `package-directory-list' and the Package Menu will
+always respect that.
+
 *** If a package is available on multiple archives and one has higher
 priority (as per `package-archive-priorities') only that one is
 listed. This can be configured with `package-menu-hide-low-priority'.
diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 7968ecde127..615631383e7 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -2457,7 +2457,9 @@ of these dependencies, similar to the list returned by
          (t "disabled"))))
      (dir                               ;One of the installed packages.
       (cond
-       ((not (file-exists-p (package-desc-dir pkg-desc))) "deleted")
+       ((not (file-exists-p dir)) "deleted")
+       ;; Not inside `package-user-dir'.
+       ((not (file-in-directory-p dir package-user-dir)) "external")
        ((eq pkg-desc (cadr (assq name package-alist)))
         (if (not signed) "unsigned"
           (if (package--user-selected-p name)
@@ -2662,6 +2664,7 @@ Return (PKG-DESC [NAME VERSION STATUS DOC])."
   (let* ((status  (package-desc-status pkg))
          (face (pcase status
                  (`"built-in"  'font-lock-builtin-face)
+                 (`"external"  'font-lock-builtin-face)
                  (`"available" 'default)
                  (`"avail-obso" 'font-lock-comment-face)
                  (`"new"       'bold)
@@ -2977,6 +2980,8 @@ Optional argument NOQUERY non-nil means do not ask the user to confirm."
           ((string= sB "unsigned") nil)
           ((string= sA "held") t)
           ((string= sB "held") nil)
+          ((string= sA "external") t)
+          ((string= sB "external") nil)
           ((string= sA "built-in") t)
           ((string= sB "built-in") nil)
           ((string= sA "obsolete") t)