Thom Brown <thom@linux.com> writes:
> Hmmm... curiously, lazy (non-greedy) quantifiers are stable, such as: ((a))*?
I've found it. The triggering conditions are (1) more than one set of
capturing parens in a substring() pattern, and (2) at least one trial
midpoint failing in ccondissect() or one of its siblings. That results
in zaptreesubs() trying to clear an array entry that isn't there...
trivial to fix fortunately. So it's not so much what the quantifiers
are as whether the first attempted match succeeds.
regards, tom lane