GNU bug report logs - #17761
24.3.91; smie-for-sexp and parentheses of-by-one bug?

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

From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.91; smie-for-sexp and parentheses of-by-one bug?
Date: Thu, 12 Jun 2014 19:58:20 +0800

1. Open a buffer in octave mode and insert ( ) with point between the
   parentheses

2. Eval (smie-forward-sexp) which should give back something like
   (t 2 ")")

POS is before the token ")" instead of the end position of the token. Is
this a bug? This can often cause infinite loop if one is not careful.

BTW, although smie-config-guess's return value is not documented, it
seems no harm to do something like the following:

=== modified file 'lisp/emacs-lisp/smie.el'
--- lisp/emacs-lisp/smie.el	2014-03-04 08:35:11 +0000
+++ lisp/emacs-lisp/smie.el	2014-06-12 11:20:38 +0000
@@ -2156,7 +2156,7 @@
       (user-error "This buffer does not seem to be using SMIE"))
   (let ((config (smie-config--guess (point-min) (point-max))))
     (cond
-     ((null config) (message "Nothing to change"))
+     ((null config) (message "Nothing to change") nil)
      ((null smie-config--buffer-local)
       (message "Local rules set")
       (setq smie-config--buffer-local config))

Thanks,
Leo

Message #8 received at 17761 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Leo Liu <sdl.web <at> gmail.com>
Cc: 17761 <at> debbugs.gnu.org
Subject: Re: bug#17761: 24.3.91; smie-for-sexp and parentheses of-by-one bug?
Date: Fri, 13 Jun 2014 11:33:44 -0400

> 1. Open a buffer in octave mode and insert ( ) with point between the
>    parentheses
> 2. Eval (smie-forward-sexp) which should give back something like
>    (t 2 ")")
> POS is before the token ")" instead of the end position of the token. Is
> this a bug?

Indeed, thanks.  I installed a patch into `emacs-24' which should
fix this.  As you can see, SMIE is mostly used to parse backward!

> BTW, although smie-config-guess's return value is not documented, it
> seems no harm to do something like the following:

Using its return value is an error, so I'd rather not encourage this error.


        Stefan

Message #13 received at 17761-done <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 17761-done <at> debbugs.gnu.org
Subject: Re: bug#17761: 24.3.91; smie-for-sexp and parentheses of-by-one bug?
Date: Sat, 14 Jun 2014 00:14:34 +0800

Fixed 24.4

On 2014-06-13 11:33 -0400, Stefan Monnier wrote:
> Indeed, thanks.  I installed a patch into `emacs-24' which should
> fix this.  As you can see, SMIE is mostly used to parse backward!

Indeed and thanks for the fix.

Leo

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