bug#19102: 24.4; outline-move-subtree-up/down error at last and second-last subtree

[Stephen Berman <stephen.berman@gmx.net>]

On Fri, 21 Nov 2014 21:56:07 +0200 Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Stephen Berman <stephen.berman@gmx.net>
>> Cc: paul@tilk.co,  19102@debbugs.gnu.org
>> Date: Fri, 21 Nov 2014 18:31:19 +0100
>> 
>> >> But can C-g really take effect here?
>> >> There is no place in the function where execution halts to wait for user
>> >> feedback.
>> >
>> > C-g sets a flag that is checked by evaluation.
>> 
>> I don't understand how this could result in C-g taking effect before the
>> function finishes; could you elaborate?
>
> C-g sets a "quit" flag.  When Lisp evaluation takes place and the quit
> flag is set, the Lisp interpreter throws to top-level, thus
> interrupting whatever function was running.

Thanks for the explanation.

>> I think that, once the non-file buffer case is taken into account (and
>> not doing means moving a subtree can corrupt the outline by putting two
>> headers on the same line), the cleanest fix is basically the one Paul
>> Rankin proposed in his last post.  I've attached it as a diff against
>> emacs-24, where I assume the fix should be committed (I added a comment
>> and tweaked the function Paul posted to avoid irrelevant changes to the
>> current code, and also restricted the error handling by making it a
>> user-error and having it signal only when the user attempts to move over
>> a higher outline level, avoiding an inappropriate message at bob or
>> eob).  Does this patch qualify as a tiny change, or does Paul have a
>> copyright assignment on file (I don't have access to the file)?
>
> I don't see his assignment.  IMO, this patch is borderline wrt being
> "tiny"; I'll let Stefan judge.

Ok.

Steve Berman