bug#30132: 27.0.50; scan-sexps and ##

bug#30132: 27.0.50; scan-sexps and ##

[Michael Heerdegen]

Hello,

Insert into *scratch*

  (list ##)

and put point at the beginning of "##".  Then eval M-:

  (goto-char (scan-sexps (point) 1))

and you get

| Debugger entered--Lisp error: (scan-error "Containing expression ends prematurely" 154 155)
|   scan-sexps(152 1)
|   (goto-char (scan-sexps (point) 1))
|   eval((goto-char (scan-sexps (point) 1)) t)
|   eval-expression((goto-char (scan-sexps (point) 1)) nil nil 127)
|   funcall-interactively(eval-expression (goto-char (scan-sexps (point) 1)) nil nil 127)
|   call-interactively(eval-expression nil nil)
|   command-execute(eval-expression)

Expected is that the scan doesn't fail.

## is the rarely used representation of an interned symbol named with
the empty string.  My problem is that where it is used (like in
"org-list.el"), el-search.el gets into trouble.


Thanks in advance,

Michael.


In GNU Emacs 27.0.50 (build 17, x86_64-pc-linux-gnu, GTK+ Version 3.22.26)
 of 2018-01-15 built on drachen
Repository revision: 55a83102629d597eb172e91698578930ff193c5d
Windowing system distributor 'The X.Org Foundation', version 11.0.11905000
System Description: Debian GNU/Linux testing (buster)

bug#30132: 27.0.50; scan-sexps and ##

[Michael Heerdegen]

Michael Heerdegen <michael_heerdegen@web.de> writes:

> Hello,
>
> Insert into *scratch*
>
>   (list ##)
>
> and put point at the beginning of "##".

BTW, this is not the only kind of situation where `scan-sexps' can error
for expressions containing ##.  In particular, point doesn't necessarily
need to be directly before "##" for the problem to occur.


Michael.

bug#30132: 27.0.50; scan-sexps and ##

[Lars Ingebrigtsen]

Noam Postavsky <npostavs@gmail.com> writes:

> * elisp-mode.el (elisp-mode-syntax-propertize): New function.
> (emacs-lisp-mode): Set it as syntax-propertize-function.

I've tried the patch, and it seems to work well.  However, it makes
edebug-tests-dotted-forms hang completely, and breaks other edebug
tests.

I've poked at this briefly, but I've been unable to see what makes
things hang here.  It would be nice to get this to work -- did you get
any further in debugging these test problems, Noam?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#30132: 27.0.50; scan-sexps and ##

[Michael Heerdegen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Lars Ingebrigtsen <larsi@gnus.org> writes:
>
> > I've poked at this briefly, but I've been unable to see what makes
> > things hang here.  It would be nice to get this to work -- did you get
> > any further in debugging these test problems, Noam?
>
> The offending bit was this:
>
> (seq (group-n 1 (+ digit) "="))     ; Object label.

I wonder why.

> Which is something that should never appear in Lisp files anyway.
> [...]
> So I'm pushing Noam's patch to Emacs 29 (with that object label thing
> removed).

Thanks.  My original use case seems to be fixed.

Michael.

bug#30132: 27.0.50; scan-sexps and ##

[Lars Ingebrigtsen]

Michael Heerdegen <michael_heerdegen@web.de> writes:

> Dunno how the Edebug tests are supposed to run...:  When I load
> edebug-tests.el and run those tests with M-x ert-run-tests-interactively
> t RET, I always get lots of fails - also with what is installed now (and
> even without the patch).

I run them with "make check" or "make edebug-tests".  

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no