Issue #4044 has been updated by akr (Akira Tanaka).


Interesting example:

  % ruby -ve '("a".."z").each {|ch| p(/[\W]/i.match(ch)) }'
  ruby 2.0.0dev (2012-03-16 trunk 35049) [x86_64-linux]
  -e:1: warning: character class has duplicated range: /[\W]/
  nil
  nil
  nil
  nil
  nil
  nil
  nil
  nil
  nil
  nil
  #<MatchData "k">
  nil
  nil
  nil
  nil
  nil
  nil
  nil
  #<MatchData "s">
  nil
  nil
  nil
  nil
  nil
  nil
  nil


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Bug #4044: Regex matching errors when using \W character class and /i option
https://bugs.ruby-lang.org/issues/4044#change-25104

Author: ben_h (Ben Hoskings)
Status: Feedback
Priority: Normal
Assignee: naruse (Yui NARUSE)
Category: core
Target version: 1.9.2
ruby -v: ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-darwin10.4.0]


=begin
 Hi all,
 
 Josh Bassett and I just discovered an issue with regex matches on ruby-1.9.2p0. (We reduced it while we were hacking on gemcutter.)
 
 The case-insensitive (/i) option together with the non-word character class (\W) match inconsistently against the alphabet. Specifically the regex doesn't match properly against the letters 'k' and 's'.
 
 The following expression demonstrates the problem in irb:
 
     puts ('a'..'z').to_a.map {|c| [c, c.ord, c[/[^\W]/i] ].inspect }
 
 As a reference, the following two expressions are working properly:
 
     puts ('a'..'z').to_a.map {|c| [c, c.ord, c[/[^\W]/] ].inspect }
     puts ('a'..'z').to_a.map {|c| [c, c.ord, c[/[\w]/i] ].inspect }
 
 Cheers
 Ben Hoskings & Josh Bassett
=end



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