bug#19576: write-file writes the wrong buffer

[Alan Mackenzie]

Hello, Eli.

On Sat, Nov 21, 2015 at 01:35:02PM +0200, Eli Zaretskii wrote:
> > Date: Thu, 19 Nov 2015 18:03:39 +0200
> > From: Eli Zaretskii <eliz@gnu.org>
> > Cc: 19576@debbugs.gnu.org, andlind@gmail.com, juri@linkov.net

> > > Date: Wed, 18 Nov 2015 23:23:04 +0000
> > > Cc: martin rudalics <rudalics@gmx.at>, juri@linkov.net, andlind@gmail.com,
> > >   19576@debbugs.gnu.org
> > > From: Alan Mackenzie <acm@muc.de>

> > > > Could you try a simpler patch below?  It seems to fix both your test
> > > > case and the one originally reported in bug#21333.

> > > It does indeed fix my test case (I haven't tried it on #21333).  However
> > > it violates the specification of window-size-change-functions, which
> > > says that the hook is called _before_ redisplay, not after it has
> > > started.  I suppose one could argue over what "redisplay" means here,
> > > but intuitively I would say it is the putting of glyphs into matrices.

> > "Redisplay" is indeed not defined well enough, but the only reasonable
> > interpretation of "before redisplay" is that it happens before the
> > call to redisplay_internal.  And this is false for your suggested
> > solution as well.  It is false even by your definition, because
> > prepare_menu_bars already manipulates the glyph matrices, the ones it
> > creates for the tool bar (and also menu bar on some display types).
> > And display_echo_area also manipulates glyph matrices (it calls
> > try_window).

> > Which is only logical for an event that by itself is triggered as part
> > of redisplay!  It's redisplay that decides to resize the mini-window,
> > so calling the hook after that decision _cannot_ possibly count as
> > being "before redisplay".

> > IOW, once we, by popular demand, decided to call
> > window-size-change-functions when the mini-window is resized, we
> > invalidated that specification.  All the other callers of this hook
> > are not part of a redisplay cycle, but this one is, and cannot be
> > anywhere else.

> > So no matter what change we eventually install, the documentation of
> > the hook needs to be amended to say that it's called "before redisplay
> > or at the beginning of a redisplay cycle", and maybe also mention that
> > the second case is when the mini-window is resized.

> No further comments, so I've committed the changes I posted here
> earlier.  I also modified the documentation to be consistent with what
> the code does.

Thanks.

> Please tell me if this bug and bug#21333 could now be closed, or if
> there are any leftovers.

I don't think this fix concerns #19576.  The discussion of #21869 seems,
somehow, to have moved to here.

But I think that #21333 can be closed, and #21869 certainly can be; both
of these were about window-size-change-functions not getting called for
echo area size changes.

> Thanks.

Ditto!

-- 
Alan Mackenzie (Nuremberg, Germany).