bug#38255: 27.0.50; Indentation error-out in css-mode

bug#38255: 27.0.50; Indentation error-out in css-mode

[Lars Ingebrigtsen]

Open a.css and type:

foo {
}
}

The following backtrace is triggered.

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  smie-next-sexp(#f(compiled-function () #<bytecode 0x155d7de91a0d>) #f(compiled-function (n) #<bytecode 0x155d7f00a465>) #<subr car> #f(compiled-function (x) "Return the car of the cdr of X." #<bytecode 0x1ffc61806017>) "}")
  smie-backward-sexp("}")
  smie-indent-keyword()
  run-hook-with-args-until-success(smie-indent-keyword)
  smie-indent-calculate()
  smie-indent-line()
  indent-according-to-mode()
  electric-indent-post-self-insert-function()
  self-insert-command(1 125)
  funcall-interactively(self-insert-command 1 125)
  call-interactively(self-insert-command nil nil)
  command-execute(self-insert-command)



In GNU Emacs 27.0.50 (build 52, x86_64-pc-linux-gnu, GTK+ Version 3.24.5)
 of 2019-11-17 built on marnie
Repository revision: 3fdc36eecb3ab468eb0a55cc09a176ab503d31c3
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux 10 (buster)


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

bug#38255: 27.0.50; Indentation error-out in css-mode

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Open a.css and type:
>
> foo {
> }
> }
>
> The following backtrace is triggered.
>
> Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
>   smie-next-sexp(#f(compiled-function () #<bytecode 0x155d7de91a0d>) #f(compiled-function (n) #<bytecode 0x155d7f00a465>) #<subr car> #f(compiled-function (x) "Return the car of the cdr of X." #<bytecode 0x1ffc61806017>) "}")
>   smie-backward-sexp("}")
>   smie-indent-keyword()
>   run-hook-with-args-until-success(smie-indent-keyword)

Stefan, I tried to follow the logic in smie-backward-sexp here, but I'm
somewhat confused.  (More than usual, even.)  Could you have a look at this?

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

bug#38255: 27.0.50; Indentation error-out in css-mode

[Stefan Monnier]

>> foo {
>> }
>> }
>>
>> The following backtrace is triggered.
>>
>> Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
>>   smie-next-sexp(#f(compiled-function () #<bytecode 0x155d7de91a0d>)
>> #f(compiled-function (n) #<bytecode 0x155d7f00a465>) #<subr car>
>> #f(compiled-function (x) "Return the car of the cdr of X." #<bytecode
>> 0x1ffc61806017>) "}")
>>   smie-backward-sexp("}")
>>   smie-indent-keyword()
>>   run-hook-with-args-until-success(smie-indent-keyword)

Thanks for the great recipe.  I pushed the fix below to Emacs's master.


        Stefan


diff --git a/lisp/emacs-lisp/smie.el b/lisp/emacs-lisp/smie.el
index f2163b243e..2c2898ae71 100644
--- a/lisp/emacs-lisp/smie.el
+++ b/lisp/emacs-lisp/smie.el
@@ -702,7 +702,11 @@ smie-next-sexp
   (catch 'return
     (let ((levels
            (if (stringp halfsexp)
-               (prog1 (list (cdr (assoc halfsexp smie-grammar)))
+               (prog1 (list (or (cdr (assoc halfsexp smie-grammar))
+                                (when (string-match "\\`\\s(\\|\\s)\\(\\)\\'"
+                                                    halfsexp)
+                                  (if (match-end 1) '(0 nil) '(nil 0)))
+                                (error "Unknown token: %S" halfsexp)))
                  (setq halfsexp nil)))))
       (while
           (let* ((pos (point))