bug#74090: 31.0.50; Problems with dabbrev-expand

[Eli Zaretskii <eliz@gnu.org>]

> From: Juri Linkov <juri@linkov.net>
> Cc: Eli Zaretskii <eliz@gnu.org>,  74090@debbugs.gnu.org
> Date: Sat, 30 Nov 2024 19:51:38 +0200
> 
> >>> 1. C-x b foo RET
> >>> 2. Type: abc SPC abd
> >>> 3. C-x b *scratch* RET
> >>> 4. Type: ab M-/
> >>> 5. C-x k foo RET
> >>> 6. Type: SPC ab M-/
> >>
> >> Sorry, I meant emacs-30, not emacs-29.
> >
> > Thanks, I can reproduce it.  With the attached patch (against emacs-30)
> > I don't get the error; instead, at step 6 "ab" expands to "abc", which I
> > suppose is what's expected, and then typing `M-/' again shows the
> > message "No further dynamic expansion for ‘ab’ found", which also seems
> > as expected.  And with the patch, all current dabbrev regression tests
> > pass with ert-run-tests-batch-and-exit.  Does anyone see a problem with
> > the patch?
> 
> Thanks, I confirm it works now.

Thanks for testing.  Stephen, you have green light for installing this
on the emacs-30 branch.

> Would it be nice to have a new test that covers this case?

Definitely.  But it is less urgent than fixing the bug itself.