GNU bug report logs - #33731
26.1; cl-make-random-state copying not working

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Package: emacs;

Reported by: Xu Chunyang <mail <at> xuchunyang.me>

Date: Thu, 13 Dec 2018 21:13:02 UTC

Severity: normal

Found in version 26.1

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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From: Xu Chunyang <mail <at> xuchunyang.me>
To: 33731 <at> debbugs.gnu.org
Subject: bug#33731: 26.1; cl-make-random-state copying not working
Date: Fri, 14 Dec 2018 05:12:35 +0800

Hi,

I am reading (info "(cl) Random Numbers") on cl-make-random-state. I
expect the following returns two equal numbers, because s should be a
copy of cl--random-state thus two cl-random should use two equal
state.

(let ((s (cl-make-random-state)))
  (list (cl-random 10000)
        (cl-random 10000 s)))
;; => (6955 916)

If I didn't misunderstand this, I think it is because
cl-make-random-state uses copy-tree, however it doesn't work for
cl-structure at least in Emacs 26.1, it doesn't copy at all.

(eq (cl-make-random-state 123)
    (cl-make-random-state 123))
;; => nil

(let* ((s1 (cl-make-random-state 123))
       (s2 (cl-make-random-state s1)))
  (eq s1 s2))
;; => t
This bug report was last modified 6 years and 156 days ago.

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