Subject: bug#78944: 31.0.50; Minibuffer completion

From: Dani Moncayo <[email-masked]>
Date: Wed, 2 Jul 2025 19:41:30 +0200

Starting from 'emacs -Q', type this:
  M-x a u - f i - m o <TAB>

When I do it here, the minibuffer text completes to 'auto-fil-mode'
and the cursor goes just after the 'l'.

But, if I type '?' at that point, I see that 'auto-fill-mode' is the
only completion alternative available.  And '<TAB>' picks it as
expected.

So, why didn't the initial <TAB> pick the only possible completion alternative?

-- 
Dani Moncayo

In GNU Emacs 31.0.50 (build 44, x86_64-pc-linux-gnu, GTK+ Version
 3.24.41, cairo version 1.18.0) of 2025-07-02 built on C11-Q8YAKWONJX0
Repository revision: f48c283e885bbc5feee0804bc12f1cb633249316
Repository branch: master
Windowing system distributor 'Microsoft Corporation', version 11.0.12010000
System Description: Ubuntu 24.04.2 LTS

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LIBSELINUX LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG SECCOMP SOUND
THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINERAMA
XINPUT2 XPM XRANDR GTK3 ZLIB

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

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  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
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug lisp-mnt message mailcap yank-media puny
dired dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg
rfc6068 epg-config gnus-util text-property-search time-date subr-x
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader cl-loaddefs cl-lib sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils rmc iso-transl tooltip cconv eldoc paren
electric uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd touch-screen tool-bar dnd fontset
image regexp-opt fringe tabulated-list replace newcomment text-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
easymenu timer select scroll-bar mouse jit-lock font-lock syntax
font-core term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads dbusbind inotify
dynamic-setting system-font-setting font-render-setting cairo gtk
x-toolkit xinput2 x multi-tty move-toolbar make-network-process
tty-child-frames emacs)

Memory information:
((conses 16 39832 9463) (symbols 48 5465 0) (strings 32 12884 1934)
 (string-bytes 1 311242) (vectors 16 9587)
 (vector-slots 8 114318 3303) (floats 8 22 2) (intervals 56 243 1)
 (buffers 1064 11))