bug#62417: 30.0.50; Regression: 59ecf25fc860 is the first bad commit

[João Távora]

On Fri, Mar 24, 2023 at 4:05 PM Philip Kaludercic <philipk@posteo.net> wrote:
>
> João Távora <joaotavora@gmail.com> writes:
>
> > tag 62417 patch
> >
> > João Távora <joaotavora@gmail.com> writes:
> >
> >> I haven't yet investigated the reason.  There are other use cases inside
> >> SLY that are also failing with similar errors, but they are not as easy
> >> to trigger.
> >
> > The simples way to fix this is to make display-buffer-assq-regexp keep
> > the old protocol before trying `buffer-match-p'.
> >
> > diff --git a/lisp/window.el b/lisp/window.el
> > index 2da2f8bb2c8..0932a05aabf 100644
> > --- a/lisp/window.el
> > +++ b/lisp/window.el
> > @@ -7502,8 +7502,13 @@ display-buffer-assq-regexp
> >  the form of the action argument passed to `display-buffer'."
> >    (catch 'match
> >      (dolist (entry alist)
> > -      (when (buffer-match-p (car entry) buffer-name action)
> > -        (throw 'match (cdr entry))))))
> > +      (let ((key (car entry)))
> > +        (when (or (and (stringp key)
> > +                       (string-match-p key buffer-name))
> > +                  (and (functionp key)
> > +                       (funcall key buffer-name action))
> > +                  (buffer-match-p (car entry) buffer-name action))
> > +          (throw 'match (cdr entry)))))))
> >
> >  (defvar display-buffer--same-window-action
> >    '(display-buffer-same-window
> >
> > Another way would be to fix this in buffer-match-p.
>
> I cannot make out what is broken in `buffer-match-p'?  The patch would
> appear to me to be redundant, because both strings and functions are
> handled the same way in that function.  If you could explain the
> background, I think it would be better to fix `buffer-match-p',
> considering that this should be how it behaves.

If you pass a string to buffer-match-p, it will become
a buffer by the time it is passed to the function.  So
functions that expect strings cannot be in
buffer-display-alist after your change, whereas before
they could.

João