bug#55491: All completion fragments get added to obarray

[JD Smith]

In Emacs 27 or 28, each and every partial fragment of text introduced to the completion system gets put into obarray.  From emacs -Q:

(intern-soft "ohno") <C-M-x> -> nil

(ohno <M-TAB>                -> No match

(intern-soft "ohno") <C-M-x> -> ohno :(

This has the result that, e.g.:

(test-completion "ohno" obarray nil) <C-M-x> ; t!  Sigh

will always return t during completion, for any completed fragment.  For completion systems that complete against obarray (e.g. emacs-lisp), this is obviously undesirable.  Tracing intern doesn’t reveal any obvious places where completion fragments are being captured into the symbol array. 

In GNU Emacs 27.2 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 Version 10.14.6 (Build 18G95))

 of 2021-03-27 built on builder10-14.porkrind.org

Windowing system distributor 'Apple', version 10.3.2113

System Description:  macOS 12.3.1

Recent messages:

For information about GNU Emacs and the GNU system, type C-h C-a.

Quit

Mark set

nil

No match [2 times]

ohno

next-line: End of buffer

next-line: End of buffer

Configured using:

 'configure --with-ns '--enable-locallisppath=/Library/Application

 Support/Emacs/${version}/site-lisp:/Library/Application

 Support/Emacs/site-lisp' --with-modules'

Configured features:

NOTIFY KQUEUE ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES

THREADS JSON PDUMPER GMP

Important settings:

  value of $LANG: en_US.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

  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

  auto-composition-mode: t

  auto-encryption-mode: t

  auto-compression-mode: t

  line-number-mode: t

  transient-mark-mode: t

Load-path shadows:

None found.

Features:

(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs

format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg

epg-config gnus-util rmail rmail-loaddefs text-property-search time-date

subr-x seq byte-opt gv bytecomp byte-compile cconv 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

apropos tooltip eldoc electric uniquify ediff-hook vc-hooks

lisp-float-type mwheel term/ns-win ns-win ucs-normalize mule-util

term/common-win tool-bar dnd fontset image regexp-opt fringe

tabulated-list replace newcomment text-mode elisp-mode lisp-mode

prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer

select scroll-bar mouse jit-lock font-lock syntax facemenu font-core

term/tty-colors frame minibuffer cl-generic 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 charscript charprop case-table epa-hook

jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice loaddefs

button faces cus-face macroexp files text-properties overlay sha1 md5

base64 format env code-pages mule custom widget hashtable-print-readable

backquote threads kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:

((conses 16 46191 5995)

 (symbols 48 6035 1)

 (strings 32 15585 1651)

 (string-bytes 1 518510)

 (vectors 16 10357)

 (vector-slots 8 129155 12342)

 (floats 8 20 45)

 (intervals 56 196 0)

 (buffers 1000 12))