bug#24368: 25.1; Assertion failure in attach_marker

[martin rudalics <rudalics@gmx.at>]

 > On second thought, I don't think attach_marker should be touched at
 > all.  It is too low-level, and the assertions compile to nothing in a
 > build without --enable-checking, so we will be left without any
 > protection in the production version.

Right.  The init_iterator problem cannot be solved this way.

 > Instead, I think the callers of attach_marker should make sure charpos
 > and bytepos come from the same buffer, and are therefore in sync.  The
 > patch below implements that; WDYT?

It fixes all issues I've encountered so far ;-)

 > I agree that erroring out of goto-char in this case is sub-optimal at
 > best.

Could we drop that restriction with your changes?  I'd rather have this
handled safely at one place only.

 > I chose neither ;-)  The patch below seems to fix all of your test
 > cases, including the original problem with window-state-get, even
 > before it was fixed.  It also lifts the restriction on goto-char.
 >
 > Comments?

Install!

 > P.S. After fixing the crashes and correcting window--state-get-1,
 > running your original test case causes "C-x 1" stop working: it has no
 > effect.  Looks like this is because Emacs thinks the window is the
 > major non-side window, although actually I have *scratch* and *Help*,
 > so the command ought to work.  Is this related or unrelated to the
 > issue at hand?

I'm not sure what you mean with "stop working".  The idea is that C-x 1
when invoked in *scratch* should leave the *Help* window alone.  If you
split *scratch* via C-x 2 and after that you do C-x 1, only the other
*scratch* window should get deleted.  C-x 1 invoked in *Help* should
cause an error.

I'm currently trying to fix errors and write documentation on side
windows - that's how I stumbled into this marker issue in the first
place.

martin