automata: fix incorrect use of Aho-Corasick's "standard" semantics #1072
+50
−15
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This fixes a bug in how prefilters were applied for multi-regexes compiled with "all" semantics. It turns out that this corresponds to the regex crate's RegexSet API, but only its
is_match
routine.See the comment on the regression test added in this PR for an explanation of what happened. Basically, it came down to incorrectly using Aho-Corasick's "standard" semantics, which doesn't necessarily report leftmost matches. Since the regex crate is really all about leftmost matching, this can lead to skipping over parts of the haystack and thus lead to missing matches.
Fixes #1070