bug#67706: 30.0.50; timer-next-integral-multiple-of-time does not account for different time-zones

[Bruno Boal]

Dear maintainers,

While trying the following snippet in both Lisbon and Athens, we
get the same timer object as showed in list-timers.

(run-at-time t 14400 #'message "Testing")

What we would expect, is two different timer objects accounting for the
different time zones.

We did a edebug and found out that the function aforementioned on the
subject is always returning the same value despite of the different
local times.

Are we missing something obvious or is this a bug?

Best regards and thank you in advanced,
Bruno and Protesilaos



In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw3d
 scroll bars) of 2023-11-28 built on bb-hp-tiny
Repository revision: 7a5c91a2831602c3cd961158cf0b6a876852d7ac
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101009
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-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
LIBOTF 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