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bug#15538: 24.3; Incorrect Expansion of Nested Backquote
From: |
Stefan Monnier |
Subject: |
bug#15538: 24.3; Incorrect Expansion of Nested Backquote |
Date: |
Tue, 08 Oct 2013 00:30:45 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) |
> ``(,,@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