Update Rust crate regex to 1.10 - autoclosed

Kevin Coxrequested to merge
renovate/regex-1.x into master

This MR contains the following updates:

Package Type Update Change
regex dependencies minor 1.8 -> 1.10

Release Notes

rust-lang/regex (regex)

v1.10.2

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=================== This is a new patch release that fixes a search regression where incorrect matches could be reported.

Bug fixes:

  • BUG #​1110: Revert broadening of reverse suffix literal optimization introduced in 1.10.1.

v1.10.1

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=================== This is a new patch release with a minor increase in the number of valid patterns and a broadening of some literal optimizations.

New features:

  • FEATURE 04f5d7be: Loosen ASCII-compatible rules such that regexes like (?-u:☃) are now allowed.

Performance improvements:

  • PERF 8a8d599f: Broader the reverse suffix optimization to apply in more cases.

v1.10.0

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=================== This is a new minor release of regex that adds support for start and end word boundary assertions. That is, \< and \>. The minimum supported Rust version has also been raised to 1.65, which was released about one year ago.

The new word boundary assertions are:

  • \< or \b{start}: a Unicode start-of-word boundary (\W|\A on the left, \w on the right).
  • \> or \b{end}: a Unicode end-of-word boundary (\w on the left, \W|\z on the right)).
  • \b{start-half}: half of a Unicode start-of-word boundary (\W|\A on the left).
  • \b{end-half}: half of a Unicode end-of-word boundary (\W|\z on the right).

The \< and \> are GNU extensions to POSIX regexes. They have been added to the regex crate because they enjoy somewhat broad support in other regex engines as well (for example, vim). The \b{start} and \b{end} assertions are aliases for \< and \>, respectively.

The \b{start-half} and \b{end-half} assertions are not found in any other regex engine (although regex engines with general look-around support can certainly express them). They were added principally to support the implementation of word matching in grep programs, where one generally wants to be a bit more flexible in what is considered a word boundary.

New features:

Performance improvements:

  • PERF #​1051: Unicode character class operations have been optimized in regex-syntax.
  • PERF #​1090: Make patterns containing lots of literal characters use less memory.

Bug fixes:

  • BUG #​1046: Fix a bug that could result in incorrect match spans when using a Unicode word boundary and searching non-ASCII strings.
  • BUG(regex-syntax) #​1047: Fix panics that can occur in Ast->Hir translation (not reachable from regex crate).
  • BUG(regex-syntax) #​1088: Remove guarantees in the API that connect the u flag with a specific HIR representation.

regex-automata breaking change release:

This release includes a regex-automata 0.4.0 breaking change release, which was necessary in order to support the new word boundary assertions. For example, the Look enum has new variants and the LookSet type now uses u32 instead of u16 to represent a bitset of look-around assertions. These are overall very minor changes, and most users of regex-automata should be able to move to 0.4 from 0.3 without any changes at all.

regex-syntax breaking change release:

This release also includes a regex-syntax 0.8.0 breaking change release, which, like regex-automata, was necessary in order to support the new word boundary assertions. This release also includes some changes to the Ast type to reduce heap usage in some cases. If you are using the Ast type directly, your code may require some minor modifications. Otherwise, users of regex-syntax 0.7 should be able to migrate to 0.8 without any code changes.

regex-lite release:

The regex-lite 0.1.1 release contains support for the new word boundary assertions. There are no breaking changes.

v1.9.6

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================== This is a patch release that fixes a panic that can occur when the default regex size limit is increased to a large number.

  • BUG aa4e4c71: Fix a bug where computing the maximum haystack length for the bounded backtracker could result underflow and thus provoke a panic later in a search due to a broken invariant.

v1.9.5

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================== This is a patch release that hopefully mostly fixes a performance bug that occurs when sharing a regex across multiple threads.

Issue #​934 explains this in more detail. It is also noted in the crate documentation. The bug can appear when sharing a regex across multiple threads simultaneously, as might be the case when using a regex from a OnceLock, lazy_static or similar primitive. Usually high contention only results when using many threads to execute searches on small haystacks.

One can avoid the contention problem entirely through one of two methods. The first is to use lower level APIs from regex-automata that require passing state explicitly, such as meta::Regex::search_with. The second is to clone a regex and send it to other threads explicitly. This will not use any additional memory usage compared to sharing the regex. The only downside of this approach is that it may be less convenient, for example, it won't work with things like OnceLock or lazy_static or once_cell.

With that said, as of this release, the contention performance problems have been greatly reduced. This was achieved by changing the free-list so that it was sharded across threads, and that ensuring each sharded mutex occupies a single cache line to mitigate false sharing. So while contention may still impact performance in some cases, it should be a lot better now.

Because of the changes to how the free-list works, please report any issues you find with this release. That not only includes search time regressions but also significant regressions in memory usage. Reporting improvements is also welcome as well! If possible, provide a reproduction.

Bug fixes:

  • BUG #​934: Fix a performance bug where high contention on a single regex led to massive slow downs.

v1.9.4

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================== This is a patch release that fixes a bug where RegexSet::is_match(..) could incorrectly return false (even when RegexSet::matches(..).matched_any() returns true).

Bug fixes:

  • BUG #​1070: Fix a bug where a prefilter was incorrectly configured for a RegexSet.

v1.9.3

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================== This is a patch release that fixes a bug where some searches could result in incorrect match offsets being reported. It is difficult to characterize the types of regexes susceptible to this bug. They generally involve patterns that contain no prefix or suffix literals, but have an inner literal along with a regex prefix that can conditionally match.

Bug fixes:

  • BUG #​1060: Fix a bug with the reverse inner literal optimization reporting incorrect match offsets.

v1.9.2

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================== This is a patch release that fixes another memory usage regression. This particular regression occurred only when using a RegexSet. In some cases, much more heap memory (by one or two orders of magnitude) was allocated than in versions prior to 1.9.0.

Bug fixes:

  • BUG #​1059: Fix a memory usage regression when using a RegexSet.

v1.9.1

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================== This is a patch release which fixes a memory usage regression. In the regex 1.9 release, one of the internal engines used a more aggressive allocation strategy than what was done previously. This patch release reverts to the prior on-demand strategy.

Bug fixes:

  • BUG #​1027: Change the allocation strategy for the backtracker to be less aggressive.

v1.9.0

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================== This release marks the end of a years long rewrite of the regex crate internals. Since this is such a big release, please report any issues or regressions you find. We would also love to hear about improvements as well.

In addition to many internal improvements that should hopefully result in "my regex searches are faster," there have also been a few API additions:

  • A new Captures::extract method for quickly accessing the substrings that match each capture group in a regex.
  • A new inline flag, R, which enables CRLF mode. This makes . match any Unicode scalar value except for \r and \n, and also makes (?m:^) and (?m:$) match after and before both \r and \n, respectively, but never between a \r and \n.
  • RegexBuilder::line_terminator was added to further customize the line terminator used by (?m:^) and (?m:$) to be any arbitrary byte.
  • The std Cargo feature is now actually optional. That is, the regex crate can be used without the standard library.
  • Because regex 1.9 may make binary size and compile times even worse, a new experimental crate called regex-lite has been published. It prioritizes binary size and compile times over functionality (like Unicode) and performance. It shares no code with the regex crate.

New features:

  • FEATURE #​244: One can opt into CRLF mode via the R flag. e.g., (?mR:$) matches just before \r\n.
  • FEATURE #​259: Multi-pattern searches with offsets can be done with regex-automata 0.3.
  • FEATURE #​476: std is now an optional feature. regex may be used with only alloc.
  • FEATURE #​644: RegexBuilder::line_terminator configures how (?m:^) and (?m:$) behave.
  • FEATURE #​675: Anchored search APIs are now available in regex-automata 0.3.
  • FEATURE #​824: Add new Captures::extract method for easier capture group access.
  • FEATURE #​961: Add regex-lite crate with smaller binary sizes and faster compile times.
  • FEATURE #​1022: Add TryFrom implementations for the Regex type.

Performance improvements:

  • PERF #​68: Added a one-pass DFA engine for faster capture group matching.
  • PERF #​510: Inner literals are now used to accelerate searches, e.g., \w+@&#8203;\w+ will scan for @.
  • PERF #​787, PERF #​891: Makes literal optimizations apply to regexes of the form \b(foo|bar|quux)\b.

(There are many more performance improvements as well, but not all of them have specific issues devoted to them.)

Bug fixes:

  • BUG #​429: Fix matching bugs related to \B and inconsistencies across internal engines.
  • BUG #​517: Fix matching bug with capture groups.
  • BUG #​579: Fix matching bug with word boundaries.
  • BUG #​779: Fix bug where some regexes like (re)+ were not equivalent to (re)(re)*.
  • BUG #​850: Fix matching bug inconsistency between NFA and DFA engines.
  • BUG #​921: Fix matching bug where literal extraction got confused by $.
  • BUG #​976: Add documentation to replacement routines about dealing with fallibility.
  • BUG #​1002: Use corpus rejection in fuzz testing.

v1.8.4

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================== This is a patch release that fixes a bug where (?-u:\B) was allowed in Unicode regexes, despite the fact that the current matching engines can report match offsets between the code units of a single UTF-8 encoded codepoint. That in turn means that match offsets that split a codepoint could be reported, which in turn results in panicking when one uses them to slice a &str.

This bug occurred in the transition to regex 1.8 because the underlying syntactical error that prevented this regex from compiling was intentionally removed. That's because (?-u:\B) will be permitted in Unicode regexes in regex 1.9, but the matching engines will guarantee to never report match offsets that split a codepoint. When the underlying syntactical error was removed, no code was added to ensure that (?-u:\B) didn't compile in the regex 1.8 transition release. This release, regex 1.8.4, adds that code such that Regex::new(r"(?-u:\B)") returns to the regex <1.8 behavior of not compiling. (A bytes::Regex can still of course compile it.)

Bug fixes:

  • BUG #​1006: Fix a bug where (?-u:\B) was allowed in Unicode regexes, and in turn could lead to match offsets that split a codepoint in &str.

v1.8.3

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================== This is a patch release that fixes a bug where the regex would report a match at every position even when it shouldn't. This could occur in a very small subset of regexes, usually an alternation of simple literals that have particular properties. (See the issue linked below for a more precise description.)

Bug fixes:

  • BUG #​999: Fix a bug where a match at every position is erroneously reported.

v1.8.2

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================== This is a patch release that fixes a bug where regex compilation could panic in debug mode for regexes with large counted repetitions. For example, a{2147483516}{2147483416}{5} resulted in an integer overflow that wrapped in release mode but panicking in debug mode. Despite the unintended wrapping arithmetic in release mode, it didn't cause any other logical bugs since the errant code was for new analysis that wasn't used yet.

Bug fixes:

  • BUG #​995: Fix a bug where regex compilation with large counted repetitions could panic.

v1.8.1

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================== This is a patch release that fixes a bug where a regex match could be reported where none was found. Specifically, the bug occurs when a pattern contains some literal prefixes that could be extracted and an optional word boundary in the prefix.

Bug fixes:

  • BUG #​981: Fix a bug where a word boundary could interact with prefix literal optimizations and lead to a false positive match.

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Edited by Kevin Cox

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