bug#71401: dired-async-mode breaks dired-vc-rename-file

[Juri Linkov <juri@linkov.net>]

tags 71401 wontfix
close 71401 30.0.50
thanks

>> **** Title
>> dired-async-mode breaks dired-vc-rename-file
>>
>> **** Description
>> If dired-vc-rename-file is t and dired-async-mode is enabled, then
>> renaming a version controlled file such that the version control
>> software is aware of it will fail.
>>
>> **** Environment
>> Emacs 29.3
>>
>> **** Steps to Reproduce
>> 1. Set dired-vc-rename-file to t
>> 2. Enable dired-async-mode.
>> 3. With a git repo, rename a file via Dired.
>>
>> **** Expected Result
>> The renamed file should be reflected in git.
>>
>> **** Actual Result
>> The file is renamed and considered deleted by git.
>
> Juri, could you please look into this?

It took me a while to find that dired-async-mode is implemented
in the package emacs-async.  Then tried to rename with Wdired,
and it works.  Then tried to rename with R, and it fails with:

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  make-process(:name "emacs" :buffer #<buffer *emacs*> :stderr #<buffer *emacs:err*> ...
  async-start-process("emacs" ...
  apply(async-start-process "emacs" ...
  async-start((lambda nil (require 'cl-lib) (require 'dired-aux) ...
  dired-async-create-files(dired-rename-file "Move" ...
  dired-async--smart-create-files(...
  dired-create-files(dired-rename-file "Move" ...
  dired-do-create-files(move dired-rename-file "Move" nil t "Rename")
  dired-do-rename(nil)
  funcall-interactively(dired-do-rename nil)
  command-execute(dired-do-rename)

Then noticed that this backtrace doesn't include the function
that uses dired-vc-rename-file.  So I disabled dired-vc-rename-file,
and got the same error.

This means that the bug is not in Emacs and should be reported to the
maintainers of the emacs-async package.