From: Michael Klishin <michael.s.klishin@...>
Date: 2008-11-29T08:14:36+09:00
Subject: [ruby-core:20161] \Z? in regular expression in 1.9.1

I noticed that the following reg exp causes syntax error in 1.9.1 (I  
use tip of the branch):

/\n(\.\/)?(.*spec\.rb):[\d]+:\Z?/

To reproduce, just fire up irb of 1.9.1 and try to assign this literal  
to some variable.

The problem is with ? quantifier following \Z. I could not find any  
information about this
restriction on the web and have no Mastering regular expressions book  
at hand.

Could someone shed some light on whether it is 1.9.1 engine  
restriction, general regular expressions
restriction or possible 1.9.1 bug?

Just in case: this regexp comes from autospec in RSpec.

Thank you,

MK