Issue #19292 has been updated by nobu (Nobuyoshi Nakada). https://github.com/ruby/ruby/pull/7051 ---------------------------------------- Bug #19292: Time object's wday, yday, and isdst returns broken value (and so does to_a) when kwarg in: 'UTC' was given https://bugs.ruby-lang.org/issues/19292#change-100922 * Author: matsuda (Akira Matsuda) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0dev (2022-12-30T15:31:50Z master 0bb07e5ba4) +YJIT [arm64-darwin21] * Backport: 2.7: DONTNEED, 3.0: DONTNEED, 3.1: UNKNOWN, 3.2: REQUIRED ---------------------------------------- $ ruby -e "p Time.new(2023, 1, 1, 0, 0, 0, in: 'UTC').wday" 7 $ ruby -e "p Time.new(2023, 1, 1, 0, 0, 0, in: 'UTC').yday" 0 $ ruby -e "p Time.new(2023, 1, 1, 0, 0, 0, in: 'UTC').isdst" -e:1:in `isdst': isdst is not set yet (RuntimeError) from -e:1:in `<main>' $ ruby -e "p Time.new(2023, 1, 1, 0, 0, 0, in: 'UTC').to_a" [0, 0, 0, 1, 1, 2023, 7, 0, true, "UTC"] where the expected `to_a` value should be: [0, 0, 0, 1, 1, 2023, 0, 1, false, "UTC"] This bug seems to be happening on the following conditions: - On any given date and time, regardless of past or future - Either on `Time.new(Integer, Integer, ...)` style or `Time.new(String)` style - Only when `in: 'UTC'` kwarg was given. Other formats like `in: '+0000'` or `in: 0` seems to be OK - On all Ruby versions that accept kwarg `in:` (3.1, 3.2, and 3.3) -- https://bugs.ruby-lang.org/