From: "Eregon (Benoit Daloze) via ruby-core" <ruby-core@...>
Date: 2023-01-06T13:59:10+00:00
Subject: [ruby-core:111688] [Ruby master Bug#13671] Regexp with lookbehind and case-insensitivity raises RegexpError only on strings with certain characters

Issue #13671 has been updated by Eregon (Benoit Daloze).





@duerst Could you take a look at this? It's not fixed yet in 3.2.0.



----------------------------------------

Bug #13671: Regexp with lookbehind and case-insensitivity raises RegexpError only on strings with certain characters

https://bugs.ruby-lang.org/issues/13671#change-101088



* Author: dschweisguth (Dave Schweisguth)

* Status: Assigned

* Priority: Normal

* Assignee: duerst (Martin D��rst)

* ruby -v: 2.4.1

* Backport: 2.2: UNKNOWN, 2.3: UNKNOWN, 2.4: UNKNOWN

----------------------------------------

Here is a test program:



~~~ ruby

def test(description)

  begin

    yield

    puts "#{description} is OK"

  rescue RegexpError

    puts "#{description} raises RegexpError"

  end

end



test("ass, case-insensitive, special") { /(?<!ass)/i =~ '���' }

test("bss, case-insensitive, special") { /(?<!bss)/i =~ '���' }

test("as,  case-insensitive, special") { /(?<!as)/i  =~ '���' }

test("ss,  case-insensitive, special") { /(?<!ss)/i  =~ '���' }

test("ass, case-sensitive,   special") { /(?<!ass)/  =~ '���' }

test("ass, case-insensitive, regular") { /(?<!ass)/i =~ 'x' }



~~~



Running the test program with Ruby 2.4.1 (macOS) gives



~~~

ass, case-insensitive, special raises RegexpError

bss, case-insensitive, special raises RegexpError

as,  case-insensitive, special is OK

ss,  case-insensitive, special is OK

ass, case-sensitive,   special is OK

ass, case-insensitive, regular is OK



~~~



The RegexpError is "invalid pattern in look-behind: /(?<!ass)/i (RegexpError)"



Side note: in the real code in which I found this error I was able to work around the error by using (?i) after the lookbehind instead of //i.



Running the test program with Ruby 2.3.4 does not report any RegexpErrors.



I think this is a regression, although I might be wrong and it might be saving me from an incorrect result with certain strings.



---Files--------------------------------

test.rb (531 Bytes)





-- 

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