bug#19790: [PATCH] destructive splicing in backquote

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Robin Templeton <robin@terpri.org> writes:
>
>> Common Lisp and MACLISP define comma-dot syntax for destructive splicing
>> in backquote expressions. The Elisp reader reads ",.x" as "(\,\. x)"
>> (like ",@"), but the resulting forms are not processed by the backquote
>> library. A patch follows that adds CL-compatible comma-dot support.
>>
>> Originally reported by at Artur Malabarba in
>> <http://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00624.html>.
>
> I think the conclusion to the discussion was that we do not want to
> support the ,. operation in Emacs Lisp.
>
> (setq .foo 1)
>
> `((,.foo))
> => (((\,\. foo)))
>
> So we should remove this feature completely, because that's obviously a
> bug...

Thanks to Michael Heerdegen's pointers, I could come up with a patch.
Would something like the attached do the job?  It simply removes this
feature and adds a test.

Best regards,
Stefan Kangas

0001-Remove-support-for-destructive-splicing-in-elisp.patch
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