GNU bug report logs - #71116
30.0.50; comp-normalize-valset doesn't sort consistently

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Package: emacs;

Reported by: Daniel Clemente <n142857 <at> gmail.com>

Date: Wed, 22 May 2024 13:28:01 UTC

Severity: normal

Found in version 30.0.50

Done: Andrea Corallo <acorallo <at> gnu.org>

Bug is archived. No further changes may be made.

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From: Daniel Clemente <n142857 <at> gmail.com>
To: 71116 <at> debbugs.gnu.org
Cc: acorallo <at> gnu.org
Subject: bug#71116: 30.0.50; comp-normalize-valset doesn't sort consistently
Date: Wed, 22 May 2024 13:27:15 +0000
[Message part 1 (text/plain, inline)]
Current code from comp-cstr.el:

(defun comp-normalize-valset (valset)
  "Sort and remove duplicates from VALSET then return it."
  (cl-sort (cl-remove-duplicates valset :test #'eq)
           (lambda (x y)
             (cond
              ((and (symbolp x) (symbolp y))
               (string< x y))
              ((and (symbolp x) (not (symbolp y)))
               t)
              ((and (not (symbolp x)) (symbolp y))
               nil)
              ((or (consp x) (consp y)
                   nil))
              (t
               (< (sxhash-equal x)
                  (sxhash-equal y)))))))


This part:
              ((or (consp x) (consp y)
                   nil))

Seems like a typo; as if this was intended:
              ((or (consp x) (consp y))
                   nil)


In practice, it means it's not sorting well. The presence of a cons can
even change how the other elements are sorted:

;; This produces: ((a . 1) 2 3)
(comp-normalize-valset '(
  2
  3
  (a . 1)
))

;; This produces: (2 3 (a . 1))
(comp-normalize-valset '(
  (a . 1)
  2
  3
))

;; This produces: (3 (a . 1) 2)
(comp-normalize-valset '(
  2
  (a . 1)
  3
))

Since all three examples use a list with the same elements, I would expect
the same result after sorting: a sorted list (by some definition of
sorted). Otherwise the function documentation must be adjusted.

I'm just reporting this because I was reading new code and found this part
hard to understand. I'm not familiar with the comp-cstr.el code or with how
this affects native compilation, or whether there's any bug. My example
doesn't represent how the actual code is used.

For context, the original intention was to avoid comparing conses with
sxhash-equal.
https://lists.gnu.org/archive/html/emacs-devel/2024-02/msg00406.html
[Message part 2 (text/html, inline)]

This bug report was last modified 1 year and 28 days ago.

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