bug#50470: 27.1; 'company-mode' 'eshell'

[Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Hi John,

Could you explain to me some of the code of `pcomplete-parse-arguments`?
I know that was many years ago but hopefully there's still some fond
memories of how you designed it.

To be honest, the only part I sort-of understand are the first
5-6 lines.  Then comes the `(let ((begin (pcomplete-begin 'last)))` and
after that I'm lost: it doesn't look like we're parsing arguments
any more.

E.g. Why/when would pcomplete-stub contain a list rather than a string?


        Stefan


Dmitry Gutov [2022-01-24 03:50:59] wrote:

> Hi Stefan,
>
> On 23.01.2022 05:23, Stefan Monnier wrote:
>> And the 100% untested patch below is a suggestion for how to try and fix
>> those kinds of bugs.
>> Can someone try and maybe make it work?
>
> I've tried the patch, and it seems to work already, as well as fix this
> particular scenario. (Thanks!)
>
> Might as well install it, I think.
>
> There is a scenario that is more noticeably broken (yet actually better with
> this patch): a modification of bug#18951. Instead of
>
>   ls *
>
> try
>
>   ls ~/Docu*
>
> ...and [on master] the result is that the asterisk is replaced with the
>  "common part" of the possible completions automatically. If there is
>  nothing to expand with, the asterisk is similarly deleted.
>
> With your patch, we get the "Buffer is read-only" error in *Messages*
> instead, which is probably an improvement. Because it doesn't modify the
> input, nor break Company completions long-term (after the asterisk is
> removed).
>
> The offending functions is pcomplete-parse-arguments. There is some complex
> global state going on there, but the following addition seems to fix the
> problem:
>
> @@ -790,6 +804,9 @@ pcomplete-parse-arguments
>  		   (common-stub (car completions))
>  		   (c completions)
>  		   (len (length common-stub)))
> +              (unless pcomplete-allow-modifications
> +                (setq pcomplete-stub (buffer-substring begin (point)))
> +                (throw 'pcomplete-completions completions))
>  	      (while (and c (> len 0))
>  		(while (and (> len 0)
>  			    (not (string=
>
>
> Not sure if this new value of pcomplete-stub is always TRT, but it has
> passed a bunch of my experiments successfully.