Eli Zaretskii <eliz@gnu.org> writes:

> > The code wants to do this in `dired-rename-subdir-1':
> >
> >     (if (equal dir default-directory)
> > 	;; if top level directory was renamed, lots of things have to be
> > 	;; updated:
> >
> > DIR is the old directory name.  But the `equality' test fails simply
> > because default-directory is "~/test/" but DIR has the tilde expanded.
>
> So all we need to do is call expand-file-name on both of them?  Or do
> we need also to call file-truename?

A sign of life with intermediate results:

Turns out this is a difficult and not even the only question (see
below).  It looks to me like this branch of the code (after the always
failing test) was never in use, or only a very long time ago.  Because
that unreachable branch is broken in several ways.

I needed to add a `file-name-as-directory' wrapper, else dired wouldn't
recognize the new directory as a directory and treats the file name as a
wildcard instead.

I would also add `abbreviate-file-name' calls so that the format of the
file names is like before (abbreviated).  Finally I don't understand why
the existing code computes `default-directory' and `dired-directory'
differently, so I reduced that to one computation for now, but also see
below for more.

This took me to this first actually working version for the
simplest case: