From: Florian Gross <florgro@...>
Date: 2007-07-02T01:56:22+09:00
Subject: [BUG] String#rindex with Regexp in 1.9

Hi,

in 1.8: (ruby 1.8.4 (2005-12-24))

"blablabla".rindex("bla", 0) # => 0
"blablabla".rindex(/bla/, 0) # => 0

["test1".rindex(/../, 2), Regexp.last_match.to_s] # => [2, "st"]
["test1".rindex(/.../, 2), Regexp.last_match.to_s] # => [2, "st1"]

That is, for both strings and regular expressions a match occurs if
the first matched character's index is <= start_offset.

In 1.9: (ruby 1.9.0 (2007-06-30 patchlevel 0))

"blablabla".rindex("bla", 0) # => 0
"blablabla".rindex(/bla/, 0) # => nil

["test1".rindex(/../, 2), Regexp.last_match.to_s] # => [1, "es"]
["test1".rindex(/.../, 2), Regexp.last_match.to_s] # => [0, "tes"]

For regular expressions a match now occurs if the last matched
character's index is <= start_offset. For strings the behaviour is the
same as in 1.8.

The expectation is that str.rindex(substr, offset) should always be ==
str.rindex(Regexp.new(Regexp.escape(substr)), offset)

Kind regards,
Florian Gross