GNU bug report logs - #15538
24.3; Incorrect Expansion of Nested Backquote

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Package: emacs;

Reported by: 白井 彰 <okshirai <at> gmail.com>

Date: Sun, 6 Oct 2013 11:24:02 UTC

Severity: normal

Found in version 24.3

Fixed in version 24.4

Done: Glenn Morris <rgm <at> gnu.org>

Bug is archived. No further changes may be made.

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From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: 白井 彰 <okshirai <at> gmail.com>
Cc: 15538 <at> debbugs.gnu.org
Subject: bug#15538: 24.3; Incorrect Expansion of Nested Backquote
Date: Tue, 08 Oct 2013 00:30:45 -0400

> ``(,,@q)
> (\` ((\, r s)))
> ((3 5))                                 ; Incorrect: This should be ((3 5)
> (4 6))

Indeed, it's incorrect, but I think the intention of the current code is
to consider the above expression as invalid, so the error is to return
a value at step 2 (ignoring the second argument `s' to the unquote)
instead of signalling an error.

If you really want that result, you can do

 ``(,@(list ,@q))


> ``(,@,@q)

And here, you'd have to use

  ``(,@(append ,@q))

I installed a patch into trunk which catches the above problems and
signals an error if/when encountering such situations.
Thank you,


        Stefan
This bug report was last modified 11 years and 267 days ago.

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