Subject: bug#27016: possible bug in `defsetf'

From: [email-masked]
Date: Mon, 22 May 2017 08:11:25 -0400

tags 27016 unreproducible
quit

Rafael D Sorkin <[email-masked]> writes:

> 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) !

I'm not able to reproduce this behaviour on 24.5, the second setf throws
an error just like the first.  How are you evaluating these exactly
(starting from emacs -Q)?  I tried C-x C-e on each sexp in turn.