Yukihiro "Matz" Matsumoto d21eceb286 mruby-regexp: disable first-byte skip when pattern can match empty ...

first_set_walk returned TRUE when it reached RE_MATCH via epsilon
transitions, but that's exactly the case where the optimization is
wrong: an empty-matchable pattern can start matching at any position,
including bytes that aren't in the computed first-byte set. The
skip-ahead loop in pike_vm then advanced past valid empty-match
positions, producing a match at the wrong offset (e.g. /a?/.match("b")
reported the empty match at index 1 instead of 0).

Co-authored-by: Claude <noreply@anthropic.com>

2026-05-23 09:58:31 +09:00

..

regexp.rb

mruby-regexp: disable first-byte skip when pattern can match empty

2026-05-23 09:58:31 +09:00