[Issue 9211] regex lookahead, (?=(\d\d\d)+\b) failed

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=9211


Dmitry Olshansky <dmitry.olsh at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dmitry.olsh at gmail.com


--- Comment #1 from Dmitry Olshansky <dmitry.olsh at gmail.com> 2012-12-27 08:15:19 PST ---
Now that was neasty.
The bug lurked in a branch-test code of *-repetition. It was too optimistic
optimization and it was curbed down back then. Looks like one case slipped
through.

The reduced test case doesn't require lookahead at all: 

version A1 prints [["123", "12", "3"]] (!!)
version A2 prints [["1234", "3", "4"]]

The bug is triggered in a specific scenarios but is quite deadly.

import std.regex, std.stdio;

int main(string[] args)
{
    version(A1)
    {
      auto rx_1 =  regex(r"^(\w)*(\d)");
      auto m = match("1234", rx_1);  
      auto captures = m.front;
      writefln("%s", captures);
    }
    version(A2)
    {
      auto rx_2 = regex(r"^([0-9])*(\d)");
      auto m2 = match("1234", rx_2);
      auto captures2 = m2.front;
      writefln("%s", captures2);
    }
    return 0;
}

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------