bug#56865: M-x find-dired fails with "Wrong type: processp, nil"

[Paul Pogonyshev]

Seems so. I guess with the way Elisp works it is even correct, because (as I understand) Elisp has no way to notice that process has died if there are no IO calls between `shell-process' and `set-process-*'. But it does feel dirty. (Also that `(sit-for 1)'  a few lines above feels dirty.)

Paul

On Tue, 2 Aug 2022 at 12:35, Lars Ingebrigtsen <larsi@gnus.org> wrote:

Paul Pogonyshev <pogonyshev@gmail.com> writes:

> Tested also with `emacs -Q', so this is not a problem of my configuration.
>
> 1. Open (a slow) remote connection, with TRAMP
> 2. Run M-x find-dired RET, arguments not important
> 3. Internal error "Wrong type: processp, nil" appears
>
> Debugging suggests that it happens in `find-dired-with-command' when calling
> `set-process-filter'. Apparently the asynchronously started shell command started ~
> 30 lines above counts as having finished (?) by then.

The proper fix here would be to have a way to specify the
filter/sentinel in `shell-command', since that's the only way to really
guarantee that we'll be getting the output here.

But some testing seems to indicate that just moving the settings up
until right after the `shell-command' makes things work, so I've now
made that trivial fix in Emacs 29.  Does this fix this issue for you,
too?