bug#49215: 28.0.50; 'display-time-mode' and 'which-function-mode' not interacting well with 'tab-bar-format-global'

[Martin Marshall]

I've just noticed that somehow in copying the code into my email
below, a "t" was somehow replaced with a "T".

Please accept my apology. Below is the correction.

    (setq tab-bar-format
     '(tab-bar-format-tabs
      tab-bar-separator
      tab-bar-format-align-right
      tab-bar-format-global))

    (tab-bar-mode t)

    (display-time-mode t)

    (which-function-mode t)

On Thu, Jun 24, 2021 at 8:20 PM Martin Marshall <law@martinmarshall.com> wrote:
>
> Hello, I'm trying use 'which-function-mode' and also have time appear on
> the right end of the tab-bar but not in the modeline per documentation for
> the 'tab-bar-format' variable:
>
>     When you add more items ‘tab-bar-format-align-right’ and
>     ‘tab-bar-format-global’ to the end, then after enabling
>     ‘display-time-mode’ (or any other mode that uses ‘global-mode-string’)
>     it will display time aligned to the right on the tab bar instead of
>     the mode line.
>
> It seems this only works without 'which-function-mode'.  If I enable
> 'which-function-mode' after tab-bar-mode, time unexpectedly reappears in
> the modeline.
>
> Alternatively, if I enable 'which-function-mode' before 'tab-bar-mode',
> then time appears only in the tab-bar, as expected.  But then the
> information provided by 'which-function-mode' also stops appearing in the
> modeline.
>
> Steps to reproduce:
> 1. Start Emacs with "emacs -Q".
> 2. Paste into scratch buffer:
>
>    (setq tab-bar-format
>     '(tab-bar-format-tabs
>      tab-bar-separator
>      tab-bar-format-align-right
>      Tab-bar-format-global))
>
>    (tab-bar-mode t)
>
>    (display-time-mode t)
>
>    (which-function-mode t)
>
> 3. "M-x eval-buffer RET"
>
> To reproduce the other result---wherein 'which-function-mode'
> disappears from the modeline and will not return---simply repeat the
> above steps with the "(which-function-mode t)" line placed above the
> "(tab-bar-mode t)" line instead of beneath it.
>
> With warm regards,
> Martin Marshall
>
>
>
> In GNU Emacs 28.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version
> 3.24.29, cairo version 1.17.4)
>  of 2021-06-24 built on machine
> Repository revision: 1283e1db9b7750a90472e7d557fdd75fcaff6446
> Repository branch: makepkg
> Windowing system distributor 'The X.Org Foundation', version 11.0.12101001
> System Description: EndeavourOS
>
> Configured using:
>  'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
>  --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
>  --with-sound=alsa --with-modules --without-gconf --with-gsettings
>  --enable-link-time-optimization --with-native-compilation
>  --with-x-toolkit=gtk3 --without-xaw3d --with-xwidgets
>  --without-compress-install
>  '--program-transform-name=s/\([ec]tags\)/\1.emacs/'
>  'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions
>  -Wp,-D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security
>  -fstack-clash-protection -fcf-protection -flto -fuse-linker-plugin'
>  LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'
>
> Configured features:
> ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
> JSON LCMS2 LIBOTF LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP NOTIFY
> INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
> X11 XDBE XIM XPM XWIDGETS GTK3 ZLIB
>
> Important settings:
>   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=ibus
>   locale-coding-system: utf-8-unix
>
> Major mode: Lisp Interaction
>
> Minor modes in effect:
>   display-time-mode: t
>   which-function-mode: t
>   tooltip-mode: t
>   global-eldoc-mode: t
>   eldoc-mode: t
>   electric-indent-mode: t
>   mouse-wheel-mode: t
>   tool-bar-mode: t
>   tab-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
> rfc822 mml mml-sec epa derived epg epg-config gnus-util rmail
> rmail-loaddefs auth-source eieio eieio-core cl-macs eieio-loaddefs
> password-cache json map mm-decode mm-bodies mm-encode mail-parse rfc2231
> mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
> mm-util mail-prsvr mail-utils pp cl-print time cl-seq find-func cl-extra
> shortdoc text-property-search seq byte-opt gv bytecomp byte-compile
> cconv help-fns radix-tree help-mode add-log which-func imenu time-date
> subr-x cl-loaddefs cl-lib iso-transl tooltip eldoc electric uniquify
> ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
> term/common-win x-dnd 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 easymenu
> timer select scroll-bar mouse jit-lock font-lock syntax 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 button
> loaddefs faces cus-face macroexp files window text-properties overlay
> sha1 md5 base64 format env code-pages mule custom widget
> hashtable-print-readable backquote threads xwidget-internal dbusbind
> inotify lcms2 dynamic-setting system-font-setting font-render-setting
> cairo move-toolbar gtk x-toolkit x multi-tty make-network-process
> native-compile emacs)
>
> Memory information:
> ((conses 16 85954 5287)
>  (symbols 48 7128 0)
>  (strings 32 21905 1841)
>  (string-bytes 1 724005)
>  (vectors 16 14068)
>  (vector-slots 8 261486 10398)
>  (floats 8 82 28)
>  (intervals 56 621 0)
>  (buffers 992 13))