Issue #21199 has been updated by nobu (Nobuyoshi Nakada). Status changed from Feedback to Third Party's Issue Backport changed from 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN to 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED YAML has no specification of calendar systems. If YAML specifies it, we would obey it of course. Until then, YAML is not suitable for such dates, just don't use such dates. ---------------------------------------- Bug #21199: Psych.dump and load on Date before 1582-10-15 https://bugs.ruby-lang.org/issues/21199#change-112469 * Author: fitmap (Justin Peal) * Status: Third Party's Issue * ruby -v: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x64-mingw-ucrt] * Backport: 3.1: DONTNEED, 3.2: DONTNEED, 3.3: DONTNEED, 3.4: DONTNEED ---------------------------------------- The code is: ```ruby require 'date' require 'psych' date = Date.new(1582, 10, 4) p "date=#{date.inspect}" str = Psych.dump(date, permitted_classes: [Date]) p "str=#{str}" date2 = Psych.load(str, permitted_classes: [Date]) p "date2=#{date2.inspect}" ``` The output is: ``` "date=#<Date: 1582-10-04 ((2299160j,0s,0n),+0s,2299161j)>" "str=--- 1582-10-14\n" "date2=#<Date: 1582-10-14 ((2299160j,0s,0n),+0s,-Infj)>" ``` -- https://bugs.ruby-lang.org/