Clock module shows incorrect time after tzdata upgrade to 2026b (Pacific timezone)

[12Prats]

System:

• OS: Arch Linux
• Waybar: waybar-git 0.15.0.r167.gcca8dc3-1
• GCC: 15.2.1 20260209
• Timezone: America/Vancouver (PDT, -0700)
• Compiled with HAVE_CHRONO_TIMEZONES=1 (C++20 std::chrono)

Problem:
After upgrading tzdata to 2026b, the Waybar clock module shows
time 1 hour behind (PST -0800 instead of PDT -0700). All other
system tools show correct time.

Root cause identified:
tzdata 2026b breaks C++20 std::chrono timezone handling in Waybar
for the Pacific timezone. Downgrading to tzdata 2026a fixes the issue.

Steps to reproduce:

1. Set timezone to America/Vancouver
2. Install tzdata 2026b
3. Launch Waybar — clock shows 1 hour behind

Workaround:
Downgrade tzdata to 2026a and pin it in /etc/pacman.conf:
IgnorePkg = tzdata

[Mrpaoo]

I guess it is std::chrono module to blame, according to this code

#include <ctime>
#include <chrono>
#include <iostream>

int main() {
    auto now = std::chrono::system_clock::now();
    std::time_t t = std::chrono::system_clock::to_time_t(now);


    setenv("TZ", "America/Vancouver", 1);
    tzset();
    std::tm* local = std::localtime(&t);
    std::cout << "libc:   " << std::asctime(local);

  
    const auto* tz = std::chrono::locate_zone("America/Vancouver");
    auto zt = tz->to_local(now);
    
   
    auto days = std::chrono::floor<std::chrono::days>(zt);
    std::chrono::year_month_day ymd{days};
    auto hh = std::chrono::floor<std::chrono::hours>(zt - days);
    auto mm = std::chrono::floor<std::chrono::minutes>(zt - days - hh);
    auto ss = std::chrono::floor<std::chrono::seconds>(zt - days - hh - mm);
    
    std::cout << "chrono: "
              << static_cast<int>(ymd.year()) << "-"
              << static_cast<unsigned>(ymd.month()) << "-"
              << static_cast<unsigned>(ymd.day()) << " "
              << hh.count() << ":"
              << mm.count() << ":"
              << ss.count() << "\n";
}

g++ -std=c++20 time.cc -o time_check

Output:
libc: Mon Apr 27 23:51:34 2026
chrono: 2026-4-27 22:51:34

output of chrono later one hour. I think tzdata just change some format of timezone file, and chrono cant no handle that properly. And waybar just use the chrono instead of libc

A workaround maybe consider fallback to locale time when locale time inequal std::chrono

[Shup04]

I was having this issue since we switched from PST to PDT too.

As a temporary workaround, i just setup a custom clock module that calls the system 'date' command:

"custom/clock": {
  "exec": "date '+ %I:%M %p'",
  "interval": 1,
}