regex-syntax: escape ASCII whitespace in escape() and escape_into()#1353
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regex-syntax: escape ASCII whitespace in escape() and escape_into()#1353tryHivemind wants to merge 1 commit into
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escape() documents that its output "may be safely used as a literal in
a regular expression", but unescaped whitespace characters break that
guarantee when the result is embedded in a verbose-mode group (?x:...),
where ASCII whitespace is treated as insignificant and ignored:
let lit = regex_syntax::escape(" "); // returns " "
Regex::new(&format!("^(?x:{lit})$")).unwrap().is_match(" ") // false!
Fix escape_into() to emit \xNN hex escapes for ASCII whitespace
characters, making the output valid in all regex contexts including
verbose mode. Non-ASCII whitespace (e.g. U+2000 EN QUAD) is not a
concern because verbose mode only ignores ASCII whitespace per the
regex crate's own definition.
Fixes #1323
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escape() output is not safe inside verbose mode (?x:...) where ASCII whitespace is ignored, breaking the documented guarantee. Fix escape_into() to emit hex escapes for ASCII whitespace so output is valid in all regex contexts. Fixes #1323