bug#62732: 29.0.60; uniquify-trailing-separator-p affects any buffer whose name matches a dir in CWD

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: sbaugh@catern.com,  62732@debbugs.gnu.org
> Date: Mon, 10 Jul 2023 22:55:23 -0400
> 
> >> No, `create-file-buffer` used to throw away the trailing slash, rather
> >> than make use of this information.
> 
> [ And instead uniquify had to try and recover that information by checking
>   the file-system.  ]
> 
> >> Not sure why Dired bothered to remove the tailing slash when calling
> >> it, maybe because a long time ago `create-file-buffer` had a bug if
> >> the name had a trailing slash.
> > So why the need for the change in dired.el?
> 
> Because we do want Dired to tell `create-file-buffer` that this is
> a directory and it should thus obey `uniquify-trailing-separator-p`.

When will we NOT want to tell create-file-buffer that the file is a
directory?  Your original response, viz.:

> I think the fact that the callers get to control this regardless of
> whether there is a file or directory by that name is one of the best
> part of this change.

seemed to indicate that there are cases where we would not want
create-file-buffer to know that, but I suspect that we will always
want, because otherwise uniquify will not work in those cases, and
Spencer will report a bug.

My comments assumed that indeed we will (almost) always want to tell
create-file-buffer this is a directory.