28.0.50; Proposal: slightly more efficient package-quickstart.el

[Arthur Miller <arthur.miller@live.com>]

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The puropose of "quickstart" file is to perform some calculations
offline to speed up startup time, and what I see in generated code that
every package is added to load-path with `add-to-list' function, which
will ensure that each object is added only once.

Since quickstart file is created by iterating through each and one
installed package whose path is already known, this calculation can be
performed once at generation time, rather than every time when Emacs
starts. It is relatively simple to alter the generator routine for this,
I have included patch. I have been doing something similar in my
personal init file since quite some time now and have not had problems,
but I am not that sofisticated user.

I guess this won't speed thing much, maybe people who use large number
of packages could see some difference. Regardless it is still an
unnecessary computation and thus waste of cpu (and battery) to do this
every startup if it can be done only once when package-quickstart.el is
generated.


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--- ../emacs/lisp/emacs-lisp/package.el	2021-07-11 12:20:59.257657537 +0200
+++ ./package.el	2021-07-20 02:01:38.050169037 +0200
@@ -4137,7 +4137,8 @@
         (package-activated-list ())
         ;; Make sure we can load this file without load-source-file-function.
         (coding-system-for-write 'emacs-internal)
-        (Info-directory-list '("")))
+        (Info-directory-list '(""))
+        paths)
     (dolist (elt package-alist)
       (condition-case err
           (package-activate (car elt))
@@ -4155,6 +4156,7 @@
                 (let ((load-suffixes '(".el" ".elc")))
                   (locate-library (package--autoloads-file-name pkg))))
                (pfile (prin1-to-string file)))
+          (push (package-desc-dir pkg) paths)
           (insert "(let ((load-true-file-name " pfile ")\
 (load-file-name " pfile "))\n")
           (insert-file-contents file)
@@ -4164,6 +4166,10 @@
               (replace-match (if (match-end 1) "" pfile) t t)))
           (unless (bolp) (insert "\n"))
           (insert ")\n")))
+      (goto-char (point-min))
+      (while (re-search-forward "^(add-to-list.*load-path" nil t)
+        (goto-char (line-beginning-position))
+        (kill-sexp))
       (pp `(setq package-activated-list
                  (append ',(mapcar #'package-desc-name package--quickstart-pkgs)
                          package-activated-list))
@@ -4175,6 +4181,10 @@
                       (setq Info-directory-list
                             (append ',info-dirs Info-directory-list)))
               (current-buffer))))
+      (goto-char (point-min))
+      (forward-line 3)
+      (insert (concat "\n(nconc load-path '" (prin1-to-string paths) ")\n"))
+      (goto-char (point-max))
       ;; Use `\s' instead of a space character, so this code chunk is not
       ;; mistaken for an actual file-local section of package.el.
       (insert "\f