bug#58921: Tab completion hangs in eshell

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

> So we just need to fix the case where the argument matches "\\`--.*=". I'm
> still not really clear on all the details of how Pcomplete works, but
> I think case (2) works because of this code just before my diff:
>
>   (if (pcomplete-match "^--\\([^= \t\n\f]*\\)\\'" 0)
>       ;; FIXME: Extract this list from "tar --help".
>       (pcomplete-here*
>        '("--absolute-names"
>          ;; ...
>          "--volno-file=")))
>
> That is, if we have an arg starting with "--" and without an "=", call
> 'pcomplete-here*'. Even the arg doesn't match anything in that list, it
> should still move forward (I think). However, when we have an "=" in the
> arg, the function instead evaluates the 'cond' block that I modified, so it
> needs to be sure to call 'pcomplete-here*' (or some other function) to make
> forward progress.

The way I see it, either we still have an inf-loop or your
(pcomplete-match "\\`--.*=" 0) condition is redundant.

From what you say the inf-loop should only manifest if we match neither

    (pcomplete-match "^--\\([^= \t\n\f]*\\)\\'" 0)

nor

    (pcomplete-match "\\`--.*=" 0)

and indeed:

    tar --pot\ <TAB>

seems to hang.


        Stefan