GNU bug report logs - #70524
[PATCH] Fix `map-elt` with `setf` for subplaces

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Okamsn <okamsn <at> protonmail.com>
Subject: bug#70524: closed (Re: bug#70524: [PATCH] Fix `map-elt` with
 `setf` for subplaces)
Date: Mon, 06 May 2024 14:02:02 +0000

[Message part 1 (text/plain, inline)]

Your bug report

#70524: [PATCH] Fix `map-elt` with `setf` for subplaces

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 70524 <at> debbugs.gnu.org.

-- 
70524: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=70524
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

[Message part 2 (message/rfc822, inline)]

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: 70524-done <at> debbugs.gnu.org
Subject: Re: bug#70524: [PATCH] Fix `map-elt` with `setf` for subplaces
Date: Mon, 06 May 2024 16:02:01 +0200

Hello,

It seems the discussion has come to an end, and we have not decided to
do anything, so I'm closing this report for now.

Feel free to reopen when there is something new, or to continue
discussing other aspects in this or other/new bug reports.


Thank you,

Michael.

[Message part 3 (message/rfc822, inline)]

From: Okamsn <okamsn <at> protonmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: [PATCH] Fix `map-elt` with `setf` for subplaces
Date: Tue, 23 Apr 2024 02:10:42 +0000

[Message part 4 (text/plain, inline)]

Hello,

Currently, the use

     (let ((arr (vector 0 1 2 3 4 5 6)))
       (setf (map-elt (cl-subseq arr 3) 0)
             27)
       arr)

expands to

     (let ((arr (vector 0 1 2 3 4 5 6)))
       (let* ((v arr))
         (condition-case nil
             (with-no-warnings
               (map-put! (cl-subseq v 3) 0 27 nil))
           (map-not-inplace
            (let* ((new (map-insert (cl-subseq v 3) 0 27)))
              (progn
                (cl-replace v new :start1 3 :end1 nil)
                new))
            27)))
       arr)

which does not modify the original variable `arr` due to how `map-put!` 
is being used. With the attached patch, it would expand to

     (let ((arr (vector 0 1 2 3 4 5 6)))
       (let* ((v arr))
         (condition-case nil
             (with-no-warnings
               (let* ((m (cl-subseq v 3)))
                 (progn
                   (map-put! m 0 27 nil)
                   (let* ((new m))
                     (progn
                       (cl-replace v new :start1 3 :end1 nil)
                       new))
                   27)))
           (map-not-inplace
            (let* ((new (map-insert (cl-subseq v 3) 0 27)))
              (progn
                (cl-replace v new :start1 3 :end1 nil)
                new))
            27)))
       arr)

which correctly sets the value using `cl-replace` as the setter for 
`cl-subseq`.

Thank you.

[0001-Make-setf-with-map-elt-work-with-subplaces.patch (text/x-patch, attachment)]

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