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

[Harald Judt]

Hi,

I have posted my initial bug report here, because I first thought this
was a bug in the package vertico though it isn't:
https://github.com/minad/vertico/issues/244

The author of this package says this is an emacs bug, I am going to
quote him here because he gives more examples and in-depth explanation
than I have provided:

---
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.
---

Here is the elisp debugger backtrace for my example:
Debugger entered--Lisp error: (args-out-of-range "" 0 6)
  completion--file-name-table("" 6 completion--unquote)
  complete-with-action(completion--unquote completion--file-name-table "" 6)
  #f(compiled-function (table) #<bytecode 
0x17ceea27424a904e>)(completion--file-name-table)
  completion--some(#f(compiled-function (table) #<bytecode 
0x17ceea27424a904e>) (completion--embedded-envvar-table 
completion--file-name-table))
  read-file-name-internal("" 6 completion--unquote)
  complete-with-action(completion--unquote read-file-name-internal "" 6)
  completion-table-with-context(#("~/tmp," 0 6 (face nil)) 
read-file-name-internal "" 6 completion--unquote)
  crm--collection-fn(#("~/tmp," 0 6 (face nil)) 6 completion--unquote)
  completion--nth-completion(2 #("~/tmp," 0 6 (face nil)) crm--collection-fn 
file-directory-p 6 (metadata (category . file) (completion--unquote-requote . t)))
  #<subr completion-all-completions>(#("~/tmp," 0 6 (face nil)) 
crm--collection-fn file-directory-p 6 (metadata (category . file) 
(completion--unquote-requote . t)))
  apply(#<subr completion-all-completions> (#("~/tmp," 0 6 (face nil)) 
crm--collection-fn file-directory-p 6 (metadata (category . file) 
(completion--unquote-requote . t))))
  completion-all-completions(#("~/tmp," 0 6 (face nil)) crm--collection-fn 
file-directory-p 6 (metadata (category . file) (completion--unquote-requote . t)))
  vertico--all-completions(#("~/tmp," 0 6 (face nil)) crm--collection-fn 
file-directory-p 6 (metadata (category . file) (completion--unquote-requote . t)))
  vertico--recompute-candidates(6 #("~/tmp," 0 6 (face nil)))
  vertico--update-candidates(6 #("~/tmp," 0 6 (face nil)))
  vertico--exhibit()
  #<subr completing-read-multiple>("Directories: " read-file-name-internal 
file-directory-p t nil nil "~/")
  vertico-multiform--advice(#<subr completing-read-multiple> "Directories: " 
read-file-name-internal file-directory-p t nil nil "~/")
  apply(vertico-multiform--advice (#<subr completing-read-multiple> 
"Directories: " read-file-name-internal file-directory-p t nil nil "~/"))
  vertico--advice(#<subr completing-read-multiple> "Directories: " 
read-file-name-internal file-directory-p t nil nil "~/")
  apply(vertico--advice #<subr completing-read-multiple> ("Directories: " 
read-file-name-internal file-directory-p t nil nil "~/"))
  completing-read-multiple("Directories: " read-file-name-internal 
file-directory-p t nil nil "~/")
  elisp--eval-last-sexp(nil)
  eval-last-sexp(nil)
  funcall-interactively(eval-last-sexp nil)
  command-execute(eval-last-sexp)





In GNU Emacs 28.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.34, cairo 
version 1.16.0)
 of 2022-06-01 built on localhost
Windowing system distributor 'The X.Org Foundation', version 11.0.12101003
System Description: Gentoo Linux

Configured using:
 'configure --prefix=/usr --build=x86_64-pc-linux-gnu
 --host=x86_64-pc-linux-gnu --mandir=/usr/share/man
 --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc
 --localstatedir=/var/lib --datarootdir=/usr/share
 --disable-silent-rules --docdir=/usr/share/doc/emacs-28.1
 --htmldir=/usr/share/doc/emacs-28.1/html --libdir=/usr/lib64
 --program-suffix=-emacs-28 --includedir=/usr/include/emacs-28
 --infodir=/usr/share/info/emacs-28 --localstatedir=/var
 --enable-locallisppath=/etc/emacs:/usr/share/emacs/site-lisp
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 -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -Wl,--sort-common
 -Wl,-z,now''

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS HARFBUZZ IMAGEMAGICK JPEG JSON
LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3
ZLIB

Important settings:
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  value of $LANG: de_DE.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
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  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
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  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
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tooltip eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
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x-toolkit x multi-tty make-network-process native-compile emacs)

Memory information:
((conses 16 77319 8541)
 (symbols 48 7849 1)
 (strings 32 22068 4871)
 (string-bytes 1 760949)
 (vectors 16 17362)
 (vector-slots 8 309931 16542)
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 (intervals 56 286 0)
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Kind regards,
Harald Judt

--
`Experience is the best teacher.'

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