bug#62194: 30.0.50; Two Eglot-over-Tramp tests are failing on master, passing on emacs-29

[miha]

Eli Zaretskii <eliz@gnu.org> writes:

>> Cc: Michael Albinus <michael.albinus@gmx.de>, 62194@debbugs.gnu.org
>> Date: Fri, 17 Mar 2023 17:45:43 +0100
>> From: miha--- via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> 
>> Though I do think that if a function that calls a-p-o with
>> JUST-THIS-ONE=nil isn't internal, it should mention that it can run
>> timers in its doc string.
>
> I don't see why: timers can run in Emacs almost anywhere, so
> mentioning that in doc strings of every function makes little sense.

I'm not completely sure how timers work, but

>> But here we are talking about 'expand-file-name' and other functions
>> from tramp-sh-file-name-handler. For these, I disagree that we want them
>> to accept output from other processes and call their filters.
>> 'expand-file-name' and others are used often and, for most of the
>> existence of Emacs, they did not call proc filters. I think it's
>> dangerous to have them do it now.
>
> Process filters can be also called at any time, because they basically
> depend on when the output from a subprocess arrives.  Why would you
> want that to stop while Emacs processes expand-file-name?

From '(elisp) Output from Processes':

   Output from a subprocess can arrive only while Emacs is waiting: when
reading terminal input, in ‘sit-for’ and ‘sleep-for’, in
‘accept-process-output’, and in functions which send data to processes.

From my understanding of process.c, wait_reading_process_output normally
needs to be in the call stack in order for process filters to run.

>> 'expand-file-name' is synchronous, therefore tramp has to make it use
>> accept-process-filter (tell me if there's another way). It can use it in
>> roughly two ways: with JUST-THIS-ONE=t or JUST-THIS-ONE=nil. In the
>> first case, we hit the eglot-over-ssh freeze problem and in the second
>> case, we'll have 'expand-file-name' call timers and process filters,
>> which I explained above why I don't like.
>
> I think you should teach yourself to like that.

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