bug#81516: 31.0.91; delete-file-local-variable(-prop-line) should delete "Local Variables" block (prop-line)

Eli Zaretskii <[email protected]> writes:

>> From: Daniel Mendler <[email protected]>
>> Cc: [email protected],  [email protected],  [email protected]
>> Date: Thu, 30 Jul 2026 08:45:23 +0200
>> 
>> Eli Zaretskii <[email protected]> writes:
>> 
>> >> > The patch looks OK to me, and indeed the most important aspect is to
>> >> > remove this error.  But I think it's also a good idea to remove the
>> >> > overall block in `delete-file-local-variable(-prop-line)` when that
>> >> > block becomes empty, as a matter of aesthetics.
>> >> 
>> >> Granted, I'm not opposed to removing those, in addition to fixing the
>> >> error.
>> >
>> > I've now installed my patch on the master branch.
>> >
>> > Should we close this bug, or does anyone want to work on removing the
>> > local vars block and the prop line when they become empty?
>> 
>> Thanks. I would like to see this change. Patch attached.
>
> Thanks.  Could we please have tests for this, including in cases where
> the prop line doesn't exist, or looks similar, but isn't a prop line?

I have not found tests for file local variables. Are there any? I can
write a bunch of basic tests but this will take a little more time.

>> +      ;; Delete empty prop-line.
>> +      (when (and (eq op 'delete) deleted (= beg end))
>> +	(save-excursion
>> +	  (delete-region
>> +	   (progn
>> +	     (goto-char beg)
>> +	     (search-backward "-*-" (line-beginning-position))
>> +	     (point))
>> +	   (progn
>> +	     (goto-char end)
>> +	     (search-forward "-*-" (line-end-position))
>> +	     (point)))
>> +	  (goto-char (line-beginning-position))
>> +	  (when (looking-at-p
>> +		 (concat "^[ \t]*" (regexp-quote comment-start)
>> +			 "[ \t]*" (regexp-quote comment-end) "[ \t]*$"))
>> +	    (delete-region (point) (progn (forward-line 1) (point))))))
>
> Is this robust enough?  Wouldn't it be better to compare the entire
> line with a fixed string ";; -*- -*-" ?

I think so. Note that the first delete-region deletes only the empty -*-
-*-, since there could be other text in the comment. After that we check
if the line is empty, and in that case delete the entire line.

Daniel