GNU bug report logs - #27325
Using '&rest' without a trailing parameter causes an error in emacs 26.0.50

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: isaac lewis <isaac.b.lewis <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Using '&rest' without a trailing parameter causes an error in emacs
 26.0.50
Date: Sun, 11 Jun 2017 03:22:56 -0400

If my understanding is correct, the functions (lambda (&rest) t)
and (lambda () t) should behave similarly.

In emacs 25:

(equal (apply (lambda (&rest) t) nil)
           (apply (lambda () t) nil))
=>
t

as expected.  But evaluating the same sexp in emacs 26.0.50
causes an error.

--
Isaac Lewis

Message #8 received at 27325 <at> debbugs.gnu.org (full text, mbox):

From: Philipp Stephani <p.stephani2 <at> gmail.com>
To: isaac lewis <isaac.b.lewis <at> gmail.com>, 27325 <at> debbugs.gnu.org
Subject: Re: bug#27325: Using '&rest' without a trailing parameter causes an
 error in emacs 26.0.50
Date: Sun, 11 Jun 2017 08:15:27 +0000

[Message part 1 (text/plain, inline)]

isaac lewis <isaac.b.lewis <at> gmail.com> schrieb am So., 11. Juni 2017 um
09:24 Uhr:

> If my understanding is correct, the functions (lambda (&rest) t)
> and (lambda () t) should behave similarly.
>

From where did you get this understanding? The Elisp manual says about
&rest:
"To specify a list of zero or more extra arguments, include the
keyword &rest before one final argument."
and
"The keyword &rest (which must be followed by a single
argument name) indicates that any number of arguments can follow."
i.e. the parameter after &rest isn't optional.

[Message part 2 (text/html, inline)]

Message #11 received at 27325 <at> debbugs.gnu.org (full text, mbox):

From: npostavs <at> users.sourceforge.net
To: Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: isaac lewis <isaac.b.lewis <at> gmail.com>, 27325 <at> debbugs.gnu.org
Subject: Re: bug#27325: Using '&rest' without a trailing parameter causes an
 error in emacs 26.0.50
Date: Thu, 22 Jun 2017 06:52:10 -0400

tags 27325 notabug wontfix
close 27325
quit

Philipp Stephani <p.stephani2 <at> gmail.com> writes:

> "The keyword &rest (which must be followed by a single
> argument name) indicates that any number of arguments can follow."
> i.e. the parameter after &rest isn't optional.

I'm therefore closing this bug.  Note that omitting the parameter
doesn't work with edebug even in Emacs versions 25 and earlier (which
was the main motivation to make Emacs 26 more strict about this, if I
remember correctly).

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