compile: make Regex::new(r"(?-u:\B)") fail again #1007
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This regex failed to compile in `regex <1.8`, but the migration to regex-automata tweaked the rules in a subtle way that permitted it to compile despite the fact that the old/status-quo matching engines can't handle it correctly. By that, I mean that they may permit the \B to match between code units. That in turn results in panicking when slicing a &str. In `regex 1.9`, this regex will actually be able to be compiled, but the matching engines will correctly and robustly never report matches that split UTF-8 code units. For now, we just add code that causes `regex 1.8` to have the same behavior as previous releases. Fixes #1006
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This regex failed to compile in
regex <1.8, but the migration to regex-automata tweaked the rules in a subtle way that permitted it to compile despite the fact that the old/status-quo matching engines can't handle it correctly. By that, I mean that they may permit the \B to match between code units. That in turn results in panicking when slicing a &str.In
regex 1.9, this regex will actually be able to be compiled, but the matching engines will correctly and robustly never report matches that split UTF-8 code units. For now, we just add code that causesregex 1.8to have the same behavior as previous releases.Fixes #1006