bug#71601: 29.1; force-mode-line-update does not refresh names of tab-lines

[Al Haji-Ali]

In an `emacs -Q`, I tried the following code:

(progn
  (tab-line-mode)
  (setq-local tab-line-tab-name-function
              (defun my/tab-name(tab &optional _)
                (with-current-buffer tab
                  (concat (buffer-name) " " (format-time-string "%S"))))))

This works fine and I get the seconds after the buffer-name. However, I seem to 
have no way of updating the tab-line to cause the names to be refreshed (except 
to add or remove a tab).
The documentation of `force-mode-line-update` and the `:set` code of 
`tab-line-tab-name-function` suggest that calling `(force-mode-line-update t)` 
would do the trick, but on my Emacs, this does not work. Is this a bug or am I 
misunderstanding the documentation?

I apologize that I am unable to test this on Emacs 30.

-- Al

In GNU Emacs 29.1 (build 1, aarch64-apple-darwin22.5.0, Carbon Version
 169 AppKit 2299.6) of 2023-09-09 built on m2air.local
Windowing system distributor 'Apple Inc.', version 14.1.2
System Description:  macOS 14.1.2

Configured using:
 'configure --enable-locallisppath=/opt/homebrew/share/emacs/site-lisp
 --infodir=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0/share/info
 --mandir=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0/share/man
 --prefix=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0 --with-mac
 --enable-mac-app=/opt/homebrew/Cellar/emacs-mac/emacs-29.1-mac-10.0
 --with-gnutls --with-modules --with-mac-metal --with-native-compilation
 --with-tree-sitter 'CFLAGS=-I/opt/homebrew/opt/gcc/include
 -I/opt/homebrew/opt/libgccjit/include'
 'LDFLAGS=-L/opt/homebrew/lib/gcc/13 -I/opt/homebrew/opt/gcc/include
 -I/opt/homebrew/opt/libgccjit/include''

Configured features:
ACL GLIB GMP GNUTLS JSON LIBXML2 MODULES NATIVE_COMP NOTIFY KQUEUE
PDUMPER RSVG SQLITE3 THREADS TOOLKIT_SCROLL_BARS TREE_SITTER XIM ZLIB

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

Major mode: Lisp Interaction

Minor modes in effect:
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  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mac-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
  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:
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Memory information:
((conses 16 96353 12870)
 (symbols 48 8005 0)
 (strings 32 24415 2462)
 (string-bytes 1 758586)
 (vectors 16 19730)
 (vector-slots 8 372131 16557)
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