Issue #10891 has been updated by Yui NARUSE. Status changed from Open to Feedback It follows UTR#18's Standard Recommendation. http://www.unicode.org/reports/tr18/#punct ---------------------------------------- Bug #10891: /[[:punct:]]/ POSIX group broken (with string literals?) https://bugs.ruby-lang.org/issues/10891#change-55149 * Author: Tom Lord * Status: Feedback * Priority: Normal * Assignee: Yui NARUSE * ruby -v: ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux] * Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN ---------------------------------------- The regular expression: `/[[:punct:]]/` should match the following characters: ! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { | } ~ However, it only works for these characters: ! " # % & ' ( ) * , - . / : ; ? @ [ \\ ] _ { } And does not work for these characters: $ + < = > ^ ` | ~ However, this is where it gets really weird... Consider the following: 60.chr == "<" # true 60.chr =~ /[[:punct:]]/ # => 0 "<" =~ /[[:punct:]]/ # => nil So, it seems that the regular expression only fails for string literals! -- https://bugs.ruby-lang.org/