bug#62417: ; Regression: 59ecf25fc860 is the first bad commit

[João Távora]

On Mon, Mar 27, 2023 at 5:33 PM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > Cc: philipk@posteo.net, 62417@debbugs.gnu.org
> > Date: Mon, 27 Mar 2023 18:20:48 +0300
> > From: Eli Zaretskii <eliz@gnu.org>
> >
> > > From: João Távora <joaotavora@gmail.com>
> > > Date: Mon, 27 Mar 2023 14:08:17 +0000
> > > Cc: philipk@posteo.net, 62417@debbugs.gnu.org
> > >
> > > > since buffer-match-p accepts
> > > > both buffers and their names.  Please explain.
> > >
> > > In the patch I showed, which you and Philip approved, the docstring of
> > > the variable display-buffer-alist was clarified to state that it is a 
> > > buffer
> > > name string, and _not_ a buffer object, that is passed to buffer-match-p.
> > > This is absolutely necessary, and we've already been through this.
> >
> > I don't understand why this is necessary, and I didn't intend to limit
> > buffer-match-p to accepting only buffer names.  Please explain why is
> > it necessary.
> >
> > What I did say was that _if_ buffer-match-p will be able to accept
> > _both_ buffer names and objects _and_ will pass to the function
> > exactly the argument it was passed, i.e. either a buffer object or a
> > name of a buffer, _then_ the backward-incompatibility will be solved.
> >
> > The responsibility of making sure buffer-match-p accepts a name when
> > the function expects only names is _on_the_caller_.  And the caller is
> > NOT display-buffer, it's the Lisp code which calls display-buffer or
> > which prepares the alist that will be passed to display-buffer.
>
> To make a long story short: here's how the call to
> display-buffer-assq-regexp looked like in Emacs 28:
>
>       (let* ((user-action
>               (display-buffer-assq-regexp
>                (buffer-name buffer) display-buffer-alist action))
>
> And here's how it looks like in Emacs 29:
>
>     (let* ((user-action
>             (display-buffer-assq-regexp
>              buffer display-buffer-alist action))
>
> Your change modified display-buffer-assq-regexp to pass to
> buffer-match-p the name of the buffer if display-buffer-assq-regexp
> was called with a buffer object.  This is not TRT, since, among other
> issues, it changes the API of display-buffer-assq-regexp, which is a
> public function.

Is it?  Not documented in the manual.  Looked a lot like bog-standard
generic data-accessing implementation detail to me, and I can't
see any advantage of using it directly.

But don't let that stop you from doing this change, which, if it
works (I've given a super simple recipe to check), is 120% percent
fine by me.

João