globset: use non-capture groups in regex transform #2577
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We currently implement globs by converting them to regexes, and in doing so, sometimes use grouping. In all but one case, we used non-capturing groups. But for alternations, we used capturing groups, which was likely just an oversight. We don't make use of capture groups at all, and while they usually don't have any overhead, they lead to weird cases like this one: rust-lang/regex#1059 That particular issue is also a bug in the regex crate itself, which is fixed in rust-lang/regex#1062. Note though that the bug fix in the regex crate is required. Even with this patch to globset, memory usage is reduced (by about half in rust-lang/regex#1059) but is not returned to where it was prior to the regex 1.9 release.
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We currently implement globs by converting them to regexes, and in doing so, sometimes use grouping. In all but one case, we used non-capturing groups. But for alternations, we used capturing groups, which was likely just an oversight. We don't make use of capture groups at all, and while they usually don't have any overhead, they lead to weird cases like this one: rust-lang/regex#1059
That particular issue is also a bug in the regex crate itself, which is fixed in rust-lang/regex#1062. Note though that the bug fix in the regex crate is required. Even with this patch to globset, memory usage is reduced (by about half in rust-lang/regex#1059) but is not returned to where it was prior to the regex 1.9 release.