bug#74590: 31.0.50 [scratch/igc branch]; key input sometimes skip fcitx input method preedit box

[Yikai Zhao <yikai@z1k.dev>]

I encountered this bug while testing the mps (scratch/igc) branch. I
cannot reproduce this with the current master branch.

I'm running Linux, X11, fcitx chinese input method.

Fcitx input method is popular among CJK users. When it's enabled, all
character inputs should be displayed in the "fcitx preedit box"; until a
confirmation key (e.g. space) is pressed, the composed characters should
then be inserted into the application (e.g. emacs).

Now, with the mps branch, occasinoally, some key input would NOT go to
the fcitx preedit box; instead, it goes into emacs directly. It happens
regardless of whether the fcitx preedit box is currently active. (aka,
both first-chars and non-first-chars may have this problem). If the
fcitx preedit box is active when is happens, it would remain active.

For example, when I type "niha", it starts at this:

+----------emacs buffer---------------+
| xxxxxx|                             |
|       +-----fcitx box-------+       |
|       | niha                |       |
|       | 你好 你哈 你害 ..   |       |
|       +---------------------+       |
|                                     |
+-------------------------------------+

Then I type "o", the expected behavior is:

+----------emacs buffer---------------+
| xxxxxx|                             |
|       +-----fcitx box-------+       |
|       | nihao               |       |
|       | 你好 你哈 你害 ..   |       |
|       +---------------------+       |
|                                     |
+-------------------------------------+

But instead, what I get is:

+----------emacs buffer---------------+
| xxxxxxo|                             |
|       +-----fcitx box-------+       |
|       | niha                |       |
|       | 你好 你哈 你害 ..   |       |
|       +---------------------+       |
|                                     |
+-------------------------------------+


In GNU Emacs 31.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.22.30, cairo version 1.15.10) of 2024-11-24 built on f2908c960c38
Repository revision: 0756b1f2f5452d715396f66d887c137776e360ca
Repository branch: scratch/igc
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Ubuntu 22.04.5 LTS

Configured using:
 'configure --prefix=/work/dist/AppDir --disable-locallisppath
 --with-native-compilation=aot --with-json --with-threads --with-sqlite3
 --with-tree-sitter --with-dbus --with-xml2 --with-modules --with-libgmp
 --with-gpm --with-lcms2 --with-mps --with-x --without-pgtk
 --without-gconf --with-x-toolkit=gtk3 --with-xft --without-tiff
 --without-imagemagick --with-gif --with-png --with-rsvg --with-webp
 --with-harfbuzz --with-cairo --with-libotf --without-m17n-flt
 --with-jpeg emacs_cv_jpeglib=/usr/lib/x86_64-linux-gnu/libjpeg.a
 CPPFLAGS=-I/work/dist/AppDir/include LDFLAGS=-L/work/dist/AppDir/lib'

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG LCMS2
LIBOTF LIBXML2 MODULES MPS NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11
XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
  value of $EMACSDATA: /tmp/.mount_emacsCDP179/share/emacs/31.0.50/etc
  value of $EMACSDOC: /tmp/.mount_emacsCDP179/share/emacs/31.0.50/etc
  value of $EMACSLOADPATH: /tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp
  value of $EMACSPATH:
/tmp/.mount_emacsCDP179/libexec/emacs/31.0.50/x86_64-pc-linux-gnu
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=fcitx
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  evil-vimish-fold-mode: t
  vimish-fold-mode: t
  diff-hl-mode: t
  flycheck-posframe-mode: t
  flycheck-mode: t
  ligature-mode: t
  whitespace-mode: t
  electric-pair-mode: t
  hl-todo-mode: t
  dtrt-indent-mode: t
  projectile-mode: t
  tempel-abbrev-mode: t
  company-mode: t
  global-git-commit-mode: t
  magit-auto-revert-mode: t
  hl-line-mode: t
  display-line-numbers-mode: t
  windmove-mode: t
  recentf-mode: t
  pixel-scroll-precision-mode: t
  server-mode: t
  winner-mode: t
  global-auto-revert-mode: t
  save-place-mode: t
  vertico-mode: t
  which-key-mode: t
  global-evil-visualstar-mode: t
  evil-visualstar-mode: t
  evil-snipe-override-mode: t
  evil-snipe-override-local-mode: t
  evil-owl-mode: t
  global-evil-surround-mode: t
  evil-surround-mode: t
  evil-commentary-mode: t
  evil-mode: t
  evil-local-mode: t
  override-global-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  minibuffer-regexp-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/home/yikai/.emacs.d/lib/which-key/which-key hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/which-key
/home/yikai/.emacs.d/lib/transient/lisp/transient hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/transient
/home/yikai/.emacs.d/lib/editorconfig/editorconfig hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/editorconfig
/home/yikai/.emacs.d/lib/editorconfig/editorconfig-tools hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/editorconfig-tools
/home/yikai/.emacs.d/lib/editorconfig/editorconfig-fnmatch hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/editorconfig-fnmatch
/home/yikai/.emacs.d/lib/editorconfig/editorconfig-core hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/editorconfig-core
/home/yikai/.emacs.d/lib/editorconfig/editorconfig-core-handle hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/editorconfig-core-handle
/home/yikai/.emacs.d/lib/editorconfig/editorconfig-conf-mode hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/editorconfig-conf-mode
/home/yikai/.emacs.d/lib/compat/compat hides
/tmp/.mount_emacsCDP179/share/emacs/31.0.50/lisp/emacs-lisp/compat

Features:
(shadow sort mail-extr emacsbug evil-vimish-fold vimish-fold f s
git-gutter-fringe fringe-helper git-gutter evil-collection-diff-hl
diff-hl evil-collection-log-view log-view evil-collection-vc-dir vc-dir
ewoc vc vc-dispatcher flycheck-posframe posframe flycheck-google-cpplint
evil-collection-flycheck flycheck ligature whitespace elec-pair hl-todo
dtrt-indent company-keywords company-dabbrev-code company-dabbrev
company-files projectile evil-collection-grep grep ibuf-ext
evil-collection-ibuffer ibuffer ibuffer-loaddefs url-queue
pr-review-search tempel company-abbrev company-emoji company-emoji-list
company-capf company bazel evil-collection-xref xref which-func
testcover evil-collection-edebug edebug evil-collection-debug debug
backtrace evil-collection-python python treesit project
evil-collection-imenu imenu ffap cc-mode cc-fonts cc-guess cc-menus
cc-cmds textsec uni-scripts idna-mapping ucs-normalize uni-confusable
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evil-collection-log-edit log-edit message sendmail yank-media
evil-collection-dired dired dired-loaddefs rfc822 mml mml-sec
evil-collection-epa epa derived epg rfc6068 epg-config gnus-util
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magit-process with-editor magit-mode transient browse-url benchmark
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markdown-mode evil-collection-outline noutline outline mule-util pulse
mail-utils network-stream url-cache hl-line display-line-numbers
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mailcap let-alist gnutls puny pr-review-common
evil-collection-magit-section magit-section dash windmove cl-print igc
vertico-directory orderless recentf tree-widget wid-edit
evil-collection-consult consult cursor-sensor help-fns time pixel-scroll
cua-base auth-source-pass url-parse url-vars server fcitx dbus xml
winner evil-collection-vterm vterm evil-collection-bookmark bookmark pp
face-remap evil-collection-compile compile text-property-search
evil-collection-term term disp-table ehelp find-func vterm-module
term/xterm xterm cc-styles cc-align cc-engine cc-vars cc-defs
google-c-style midnight autorevert filenotify saveplace tramp-cache
time-stamp tramp-sh tramp trampver tramp-integration files-x
tramp-message tramp-compat xdg shell pcomplete evil-collection-comint
comint ansi-osc parse-time iso8601 time-date auth-source eieio
eieio-core password-cache json map ansi-color tramp-loaddefs cus-load
evil-collection-vertico vertico compat solarized-light-theme
solarized-theme solarized solarized-faces color
evil-collection-which-key which-key fringe-scale switch-buffer-functions
evil-visualstar evil-snipe evil-owl format-spec evil-surround
evil-commentary evil-commentary-integration
evil-collection-tabulated-list evil-collection-tab-bar
evil-collection-simple evil-collection-replace
evil-collection-process-menu evil-collection-kmacro evil-collection-info
evil-collection-indent evil-collection-help evil-collection-elisp-mode
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evil evil-integration evil-maps evil-commands evil-digraphs reveal
evil-jumps evil-command-window evil-types evil-search evil-ex
evil-macros evil-repeat evil-states evil-core advice evil-common
thingatpt rect evil-vars ring edmacro kmacro byte-opt delight comp-run
use-package use-package-ensure use-package-delight use-package-diminish
use-package-bind-key bind-key easy-mmode use-package-core
yaml-mode-autoloads xonsh-mode-autoloads with-editor-autoloads
which-key-autoloads wgrep-autoloads vterm-autoloads vimrc-mode-autoloads
vimish-fold-autoloads vertico-autoloads treesit-auto-autoloads
treepy-autoloads transient-autoloads tempel-autoloads
switch-buffer-functions-autoloads suggest-autoloads sudo-edit-autoloads
spinner-autoloads solarized-theme-autoloads s-autoloads
rust-mode-autoloads rg-autoloads rainbow-mode-autoloads pydoc-autoloads
protobuf-mode-autoloads projectile-autoloads pr-review-autoloads
posframe-autoloads popup-autoloads pkg-info-autoloads php-mode-autoloads
package-lint-autoloads org2elcomment-autoloads org-tree-slide-autoloads
orderless-autoloads markdown-mode-autoloads magit-autoloads lv-autoloads
lua-mode-autoloads lsp-pyright-autoloads lsp-mode-autoloads
lsp-haskell-autoloads loop-autoloads llama-autoloads ligature-autoloads
kotlin-mode-autoloads just-mode-autoloads jsonnet-mode-autoloads
jinx-autoloads jinja2-mode-autoloads ht-autoloads hl-todo-autoloads
haskell-mode-autoloads groovy-mode-autoloads gptel-autoloads
goto-chg-autoloads google-c-style-autoloads go-mode-autoloads
gn-mode-autoloads git-link-autoloads git-gutter-fringe-autoloads
git-gutter-autoloads ghub-autoloads fringe-helper-autoloads
flycheck-posframe-autoloads flycheck-package-autoloads
flycheck-google-cpplint-autoloads flycheck-autoloads fish-mode-autoloads
fcitx-autoloads f-autoloads explain-pause-mode-autoloads
expand-region-autoloads exec-path-from-shell-autoloads
evil-visualstar-autoloads evil-vimish-fold-autoloads
evil-surround-autoloads evil-snipe-autoloads evil-owl-autoloads
evil-commentary-autoloads evil-collection-autoloads evil-autoloads
epl-autoloads epkg-autoloads embark-autoloads emacsql-autoloads
emacs-fringe-scale-autoloads editorconfig-autoloads
ebuild-mode-autoloads dumb-jump-autoloads dtrt-indent-autoloads
dockerfile-mode-autoloads diff-hl-autoloads devdocs-browser-autoloads
delight-autoloads dash-autoloads cuda-mode-autoloads copilot-autoloads
consult-flycheck-autoloads consult-autoloads compat-autoloads
company-emoji-autoloads company-autoloads codeium-autoloads cl-macs
cmake-mode-autoloads closql-autoloads bpftrace-mode-autoloads
borg-autoloads bazel-autoloads avy-autoloads annalist-autoloads
add-node-modules-path-autoloads borg loaddefs-gen generate-lisp-file
lisp-mnt radix-tree pcase info comp cl-seq comp-cstr cl-extra help-mode
comp-common warnings icons subr-x rx gv cl-loaddefs cl-lib bytecomp
byte-compile 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
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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 lcms2 dynamic-setting system-font-setting
font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
make-network-process native-compile mps emacs)

Memory information:
((conses 24 0 0) (symbols 56 0 0) (strings 40 0 0) (string-bytes 1 0)
 (vectors 24 0) (vector-slots 8 0 0) (floats 24 0 0)
 (intervals 64 0 0) (buffers 1000 0))