To fix it the following code can be copied in a file e.g. "~/.emacs.d/fix-copy-directory.el" and make the var async-child-init point to this file. Here the code that advice copy-directory:
;; Fix bug in copy-directory
(defun dired-async--copy-directory (directory newname &optional keep-time parents copy-contents)
(interactive
(let ((dir (read-directory-name
"Copy directory: " default-directory default-directory t nil)))
(list dir
(read-directory-name
(format "Copy directory %s to: " dir)
default-directory default-directory nil nil)
current-prefix-arg t nil)))
(when (file-in-directory-p newname directory)
(error "Cannot copy `%s' into its subdirectory `%s'"
directory newname))
;; If default-directory is a remote directory, make sure we find its
;; copy-directory handler.
(let ((handler (or (find-file-name-handler directory 'copy-directory)
(find-file-name-handler newname 'copy-directory)))
(follow parents))
(if handler
(funcall handler 'copy-directory directory
newname keep-time parents copy-contents)
;; Compute target name.
(setq directory (directory-file-name (expand-file-name directory))
newname (expand-file-name newname))
;; If DIRECTORY is a symlink, create a symlink with the same target.
(if (and (file-symlink-p directory)
copy-directory-create-symlink)
(let ((target (car (file-attributes directory))))
(if (directory-name-p newname)
(make-symbolic-link target
(concat newname
(file-name-nondirectory directory))
t)
(make-symbolic-link target newname t)))
;; Else proceed to copy as a regular directory
(cond ((not (directory-name-p newname))
;; If NEWNAME is not a directory name, create it;
;; that is where we will copy the files of DIRECTORY.
(make-directory newname parents))
;; NEWNAME is a directory name. If COPY-CONTENTS is non-nil,
;; create NEWNAME if it is not already a directory.
((and copy-contents
(or parents (not (file-directory-p newname))))
(make-directory (directory-file-name newname) parents))
;; Otherwise, create NEWNAME/[DIRECTORY-BASENAME].
((not copy-contents)
(setq newname (concat newname
(file-name-nondirectory directory)))
(let ((newname-isdir (file-directory-p newname)))
;; This is needed only when running copy-directory
;; interactively. When called from dired, error happens
;; directly in first clause when trying to create a
;; directory that have the same name as file NEWNAME.
(and (file-exists-p newname)
(not newname-isdir)
(error "Cannot overwrite non-directory %s with a directory"
newname))
(unless newname-isdir (make-directory newname t))))
(t (setq follow t)))
;; Copy recursively.
(dolist (file
;; We do not want to copy "." and "..".
(directory-files directory 'full
directory-files-no-dot-files-regexp))
(let ((target (concat (file-name-as-directory newname)
(file-name-nondirectory file)))
(filetype (car (file-attributes file))))
(cond
((eq filetype t) ; Directory but not a symlink.
(copy-directory file target keep-time parents t))
((stringp filetype) ; Symbolic link
(make-symbolic-link filetype target t))
((copy-file file target t keep-time)))))
;; Set directory attributes.
(let ((modes (file-modes directory))
(times (and keep-time (file-attribute-modification-time
(file-attributes directory))))
(follow-flag (unless follow 'nofollow)))
(if modes (set-file-modes newname modes follow-flag))
(if times (set-file-times newname times follow-flag)))))))
(advice-add 'copy-directory :override #'dired-async--copy-directory)
There is actually a bug in copy-directory which is still not yet fixed in Emacs and affect of course dired-async when copying a directory to another directory that contain this same directory (overwrite directory to make it short). See https://www.reddit.com/r/emacs/comments/yha104/merging_directories_in_dired_am_i_doing_it_wrong/ https://yhetil.org/emacs-bugs/878rkw8nin.fsf@void.mail-host-address-is-not-set/T/ and https://yhetil.org/emacs-bugs/83wn8gdu4k.fsf@gnu.org/T/
To fix it the following code can be copied in a file e.g. "~/.emacs.d/fix-copy-directory.el" and make the var
async-child-initpoint to this file. Here the code that advice copy-directory: