> I guess we need to reverse the list of directories, since
> directory-files sorts using string-lessp as the predicate?
Unfortunately, `directory-files` order in `package-load-all-descriptors` is
later overlapped by `package--get-activatable-pkg` order which sorts
`package-alist` in-place.

> What does "broken" mean in this case?  I fear that your patch just
> changes what is necessary to resolve the issue in your case, but the
> underlying problem (the destructive modification of `package-list')
> still persists?

"Broken" means wrong order of versions.
As you can see in `package-process-define-package`

           (old-pkgs (assq name package-alist)))
...
              (push new-pkg-desc (cdr old-pkgs))

gives destructive modification of `package-alist` too.
We can put this destructive modification in one place, as Stefan noted,
like this

diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index ba0e3618f28..c184625d754 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -686,7 +686,7 @@ Convert EXP into a `package-desc' object using the

 If there already exists a package by the same name in
 `package-alist', insert this object there such that the packages
-are sorted with the highest version first."
+are sorted with VC and builtin packages first and the highest version
second."
   (when (eq (car-safe exp) 'define-package)
     (let* ((new-pkg-desc (apply #'package-desc-from-define (cdr exp)))
            (name (package-desc-name new-pkg-desc))
@@ -696,13 +696,29 @@ are sorted with the highest version first."
           ;; If there's no old package, just add this to `package-alist'.
           (push (list name new-pkg-desc) package-alist)
         ;; If there is, insert the new package at the right place in the
list.
-        (while
-            (if (and (cdr old-pkgs)
-                     (version-list-< version
-                                     (package-desc-version (cadr
old-pkgs))))
-                (setq old-pkgs (cdr old-pkgs))
-              (push new-pkg-desc (cdr old-pkgs))
-              nil)))
+        (progn
+          ;; Prefer newer packages
+          (while
+              (if (and (cdr old-pkgs)
+                       (version-list-< version
+                                       (package-desc-version (cadr
old-pkgs))))
+                  (setq old-pkgs (cdr old-pkgs))
+                (push new-pkg-desc (cdr old-pkgs))
+                nil))
+          (let ((pkg-desc (sort (cdr (assq name package-alist))
+                                (lambda (p1 p2)
+                                  (let ((v1 (package-desc-version p1))
+                                        (v2 (package-desc-version p2)))
+                                    (or
+                                     (and
+                                      ;; Prefer VC packages.
+                                      (package-vc-p p1)
+                                      (not (package-vc-p p2)))
+                                     ;; Prefer builtin packages.
+                                     (and
+                                      (package-built-in-p p1 v1)
+                                      (not (package-built-in-p p2
v2)))))))))
+            (setq new-pkg-desc (car pkg-desc)))))
       new-pkg-desc)))

 (declare-function package-vc-commit "package-vc" (pkg))
@@ -916,17 +932,7 @@ correspond to previously loaded files."

 (defun package--get-activatable-pkg (pkg-name)
   ;; Is "activatable" a word?
-  (let ((pkg-descs (sort (cdr (assq pkg-name package-alist))
-                         (lambda (p1 p2)
-                           (let ((v1 (package-desc-version p1))
-                                 (v2 (package-desc-version p2)))
-                             (or
-                              ;; Prefer VC packages.
-                              (package-vc-p p1)
-                              (package-vc-p p2)
-                              ;; Prefer builtin packages.
-                              (package-disabled-p p1 v1)
-                              (not (package-disabled-p p2 v2))))))))
+  (let ((pkg-descs (cdr (assq pkg-name package-alist))))
     ;; Check if PACKAGE is available in `package-alist'.
     (while
         (when pkg-descs


On Mon, Jun 5, 2023 at 12:29 AM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Евгений Бойков <artscan@list.ru>
> > Date: Mon, 5 Jun 2023 00:03:48 +1000
> > Cc: Eli Zaretskii <eliz@gnu.org>, monnier@iro.umontreal.ca,
> 63757@debbugs.gnu.org
> >
> > > Done.  Should we close the issue then, or wait for more feedback?
> >
> > fa8135f8916 * emacs-29 origin/emacs-29 Revert changes to the order in
> which package descs are
> > loaded
> > -      (dolist (pkg-dir (directory-files dir t "\\`[^.]" t))
> > +      (dolist (pkg-dir (directory-files dir t "\\`[^.]"))
> >
> > it doesn't fix the initial problem: `load-path` and `package-alist` are
> still broken in my test.
> >
> > Test:
> > To reproduce the case we need emacs 29.0.91 + fa8135f8916 fix  and
> >     ~/.emacs.d/elpa/go-mode-20170726.555/...
> >     ~/.emacs.d/elpa/go-mode-20220114.2239/...
> > Run `emacs -Q` and `M-x package-initialize`. After that `package-alist`
> and `load-path` contain the
> > 2017 version as the first item in the list (instead of 2022).
>
> I guess we need to reverse the list of directories, since
> directory-files sorts using string-lessp as the predicate?
>


-- 
__________________________

С уважением,
Бойков Евгений Алексеевич
сот. 8-924-202-25-65
e-mail: artscan@list.ru