bug#63676: cancelling editable dired causes UI problems with dired

[Michael Heerdegen <michael_heerdegen@web.de>]

Eli Zaretskii <eliz@gnu.org> writes:

> Are we sure this is the _only_ thing that needs to be updated?
> dired-revert does much more, so we should audit what it does carefully
> to determine which parts may need re-doing here.

Ok, I now had another look.  The only thing that aborting does not
100%-cleanly revert is: if option `wdired-search-replace-filenames' is
non-nil, wdired does some setup for isearch to enable the user to
query-replace only in filenames (and ignore other buffer parts).  If the
user disables that option after entering wdired, but before aborting,
the current code doesn't revert those modifications to isearch
functions.  [ Note that calling dired-revert does not help here because
it doesn't touch buffer local variables ].  I think that needs fixing,
although it is unlikely that somebody does that.

The other modifications to the dired buffer are all restored carefully.

What's left are effects that could be caused by restoring the buffer
contents with the old contents when reverting (like this issue here).

`dired-build-subdir-alist' is the only thing in dired that uses markers
not only temporarily.  All other markers are used to ease operations and
are thrown away after the operation is finished.  Overlays are not used
at all.

Text properties and file marks (those like "*") are part of the saved
buffer contents and are restored along with the contents.

Things like re-registering the dired buffer are done (`dired-advertize')
accordingly.

Some things also have already been fixed AFAIR (like the cooperation of
dired-hide-details-mode and wdired).  People have been using and testing
aborting for a long time.  I think nearly everything would have been
uncovered until now: recent related bug reports mostly discovered
problems related to recent changes to dired that not yet had been
handled by the wdired code.

It's a complex matter but I don't have more useful ideas what else could
go wrong that a `dired-revert' would fix (or not; in general).  From my
perspective my suggested change and the quality of dired and wdired wrt
this change is quite safe.


Michael.