bug#56203: 28.1; completing-read-multiple fails from inside the completion table

[Harald Judt]

Hi,

Am 24.06.22 um 23:25 schrieb Lars Ingebrigtsen:
> Harald Judt <h.judt@gmx.at> writes:
>
> > Thanks! I can confirm this on Emacs 28.1. This is an upstream
> > bug. Please report it upstream via report-emacs-bug (maybe cc Stefan
> > Monnier who is the expert on the table quotation mechanism).
> >
> >      1. I argue that Vertico calls the API completion-all-completions
> >      in the correct way.
> >      2. Icomplete use the API completion-all-completions in the same
> >      way and fails too.
> >      3. Default completion fails too if you enter ~, M-x
> >      minibuffer-complete RET. Note that completing-read-multiple
> >      overrides minibuffer-complete with crm-complete which shadows the
> >     underlying bug in the completion table.
> >      4. The error occurs from inside the completion table, and not from
> >      Vertico code.
>
> Do you have a recipe to reproduce the problem without Vertico?  I tried:
>
> (completing-read-multiple "Directories: " #'read-file-name-internal #'file-directory-p t 
> nil nil "~/")
>
> And I didn't see any obvious failures.

Number 2:
emacs -Q
Evaluate the following:
(icomplete-mode)
(completing-read-multiple "Directories: " #'read-file-name-internal 
#'file-directory-p t nil nil "~/")
Enter "~/," and behold the debugger chiming in.

Number 3 is an easy one to replicate too, but you have to enable recursive 
mini-buffers:

emacs -Q
Evaluate the following:
(setq enable-recursive-minibuffers t)
(completing-read-multiple "Directories: " #'read-file-name-internal 
#'file-directory-p t nil nil "~/")

Enter "~, " at the prompt (without quotes), then hit M-x minibuffer-complete 
RET.

Debugger entered--Lisp error: (args-out-of-range "" 0 2)
  completion--file-name-table("" 2 completion--unquote)
  complete-with-action(completion--unquote completion--file-name-table "" 2)
  #f(compiled-function (table) #<bytecode 
0x17ee37158998d04e>)(completion--file-name-table)
  completion--some(#f(compiled-function (table) #<bytecode 
0x17ee37158998d04e>) (completion--embedded-envvar-table 
completion--file-name-table))
  read-file-name-internal("" 2 completion--unquote)
[...]


--
`Experience is the best teacher.'

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