bug#72018: 30.0.60; [PATCH] Don't emit a prompt when a background Eshell process is killed

[Jim Porter <jporterbugs@gmail.com>]

On 7/10/2024 4:16 AM, Eli Zaretskii wrote:
>> Date: Tue, 9 Jul 2024 11:04:05 -0700
>> From: Jim Porter <jporterbugs@gmail.com>
>>
>> This is a regression from Emacs 29, likely due to some changes I made to
>> improve support for complex background commands. Eli, is this ok to
>> merge to the release branch?
> 
> I don't think I understand the essence of the change, and thus cannot
> appreciate its effects enough to be able to answer this.  What is the
> significance of '(car command)' in this hunk:

'command' is a "command entry", and the result of 
'eshell-commands-for-process', which returns a list of elements of the form:

     (BACKGROUND FORM PROCESSES)

BACKGROUND is non-nil if the command is being run in the background.

>> +          ;; Reset the prompt if the command we just aborted was in the
>> +          ;; foreground.
>> +          (unless (car command)
>> +            (declare-function eshell-reset "esh-mode" (&optional no-hooks))
>> +            (eshell-reset)))))))
> 
> IOW, why '(car command)' is used as an indication of a fore/background
> command?  Also, why does the comment say "foreground" while your text
> says we don't want the prompt if the killed program was in the
> background?

We want to reset the prompt (this just emits a new command prompt) for 
foreground commands, but for background commands, we don't need to do 
anything. Would it be clearer if I inverted the wording in the comment, 
like, "Don't reset the prompt if the command we just aborted was in the 
background"?