bug#64730: 30.0.50; Mark activation doesn't work after insert

[Bruno Boal]

Dear maintainers,

I'm trying to evaluate the following snippet in emacs -Q, however as
soon as I try to insert a character, the region is not highlighted
anymore. `activate- mark' doesn't make it work either. Whereas
interactively with `exchange-point-and-mark' the region gets proper highlight.

       (progn
         (insert "")
         (push-mark (line-beginning-position) :no-message :activate))

       (progn
         (insert "a")
         (push-mark (line-beginning-position) :no-message :activate))

All the best,
Bruno Boal


In GNU Emacs 30.0.50 (build 4, x86_64-pc-linux-gnu, X toolkit, Xaw3d
 scroll bars) of 2023-06-18 built on bb-hp-tiny
Repository revision: 1b0348d95934a66d9991a7331ab55e1b9a6c1367
Repository branch: makepkg
Windowing system distributor 'The X.Org Foundation', version 11.0.12101008
System Description: Manjaro Linux

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
 --with-modules --without-libotf --without-m17n-flt --without-gconf
 --with-native-compilation=yes --with-xinput2 --with-x-toolkit=lucid
 --with-xft --with-xaw3d --without-cairo --with-sound=no
 --with-tree-sitter --without-gpm --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'
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
ACL DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON LCMS2
LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG
SECCOMP SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11
XAW3D XDBE XFT XIM XINPUT2 XPM LUCID ZLIB

Important settings:
  value of $LC_COLLATE: C
  value of $LC_MESSAGES: en_US.UTF-8
  value of $LC_MONETARY: pt_PT.UTF-8
  value of $LC_NUMERIC: pt_PT.UTF-8
  value of $LC_TIME: pt_PT.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix