bug#32637: 27.0.50; window-size-change-functions not run from local hook

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 05 Sep 2018 09:47:24 +0200
> From: martin rudalics <rudalics@gmx.at>
> 
>  > window-size-change-functions needs to notify the buffer
>  > that requested such notifications via this hook.
> 
> This is a legitimate request but I'm not sure whether we should do
> that for two reasons:
> 
> The first reason is that we already run a buffer-local part of
> 'window-configuration-change-hook' and I dislike it.  Selecting a
> window and making its buffer current for the sake of running a hook is
> a bad idea IMO because both, selected window and current buffer, are
> vital informations and a function run by a hook should be aware of
> them.  Worse even, we already make the selected window's buffer
> current first which might defeat the expectations of a function run by
> the global hook.
> 
> Also the window in question might not have changed at all.  The thing
> that did change is the window configuration of a frame and it would be
> much more interesting if the hook told me what really has changed
> instead of telling me that a buffer's window might have changed.
> 
> The second reason is a purely technical one: We'd have to walk the
> window tree to find out which buffer may have been affected.  However,
> the function run by the local hook would still have to find out which
> window(s) shouwing the buffer was (were) potentially affected.  This
> means that the buffer-local function would have to walk the window
> tree a second time anyway.

I actually don't understand why we need to support buffer-local hooks
in window-size-change-functions.  This hook clearly applies to the
entire frame, so anything buffer-local sounds inappropriate there.