Issue #20097 has been updated by tompng (tomoya ishida). Not same. https://bugs.ruby-lang.org/issues/20083 is related to regexp optimization from ruby 3.2. This issue is not because it's same result in older ruby version 3.0 and 3.1 ---------------------------------------- Bug #20097: Regexp#match? with empty capture group repeat is inconsistent https://bugs.ruby-lang.org/issues/20097#change-105926 * Author: tompng (tomoya ishida) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) +MN [arm64-darwin22] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- It sometimes matches and sometimes does not, depend on repeat quantifier number. ~~~ruby # empty capture group repeat p /(a(){1,4}){2}/.match?('aa') #=> true p /(a(){1,5}){2}/.match?('aa') #=> false # repeat of capture group that match to empty string p /(a(|){1,2}){2}/.match?('aa') #=> true p /(a(|){1,3}){2}/.match?('aa') #=> false p /(a(x?y?|z){1,2}){2}/.match?('aa') #=> false ~~~ non-capturing group seems ok. ~~~ruby p /(a(?:){1,4}){2}/.match?('aa') #=> true p /(a(?:){1,5}){2}/.match?('aa') #=> true p /(a(?:|){1,2}){2}/.match?('aa') #=> true p /(a(?:|){1,3}){2}/.match?('aa') #=> true p /(a(?:x?y?|z){1,2}){2}/.match?('aa') #=> true ~~~ Same behavior in ruby 3.0, 3.1, 3.2 -- https://bugs.ruby-lang.org/