GNU bug report logs - #27016
possible bug in `defsetf'

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From: Rafael D Sorkin <rsorkin <at> perimeterinstitute.ca>
To: 27016 <at> debbugs.gnu.org
Cc: Rafael D Sorkin <rsorkin <at> perimeterinstitute.ca>
Subject: bug#27016: possible bug in `defsetf'
Date: Mon, 22 May 2017 02:39:28 -0400

Hi, 

The second behavior below seems like a bug to me.  It was not
present in emacs 23.1

Best wishes, 
Rafael Sorkin


emacs-version				; 23.1.1
(setq pair (cons 3 4))			; (3 . 4)
(foobar pair)				; Symbol's function definition is void: foobar
(setf (foobar pair) 0)			; No setf-method known for foobar 
(unless t
  (defalias 'foobar 'cons)
  (defsetf foobar setcar))		; nil 
(foobar pair)				; same as above
(setf (foobar pair) 0)			; same as above
pair					; (3 . 4)


emacs-version				; 24.5.1
(setq pair (cons 3 4))			; (3 . 4)
(foobar pair)				; Symbol's function definition is void: foobar
(setf (foobar pair) 0)			; (foobar pair) is not a valid place expression 
(unless t
  (defalias 'foobar 'cons)
  (defsetf foobar setcar))		; nil 
(foobar pair)				; same as above
(setf (foobar pair) 0)			; 0       !
pair					; (0 . 4) !


~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-
 Rafael Sorkin
 Perimeter Institute for Theoretical Physics
 31 Caroline Street North
 Waterloo, ON  N2L 2Y5
 Canada
~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-~-

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