NEWS

                          xr version history
                          ==================

Version 2.1

- Elide useless empty strings in translation to xr. For example,
  translate ^\(?:\) to bol instead of (seq bol "").

- Better empty string subset/superset check

Version 2.0

- Compatibility break: `xr-lint` and `xr-skip-set-lint` now return a
  two-level list of diagnostics, each of which now include an endpoint
  and severity field. The diagnostics are grouped so that messages
  that apply to the same problem are in the same middle-level list.

- Most warnings are now accompanied by info-level messages that point out
  related parts of the input string.

- `xr-lint` and `xr-skip-set-lint` no longer signal errors for invalid
  syntax; they are now returned as error-level messages. Other
  functions such as `xr` now signal `xr-parse-error` when the input
  string contains something that Emacs would not accept.

- Emacs version 27 or later now required

- Further performance improvements

Version 1.25
- Effective repetition of repetition check now always enabled
- Some performance improvements

Version 1.24
- \w and \W are now translated to (syntax word) and (not (syntax word)),
  instead of [[:word:]] and [^[:word:]] which are not exact equivalents.
- Repetition operators are now literals after \`. For example,
  \`* is now (seq bos "*"), not (* bos), because this is how Emacs works.
- New lint check: find [A-z] (range between upper and lower case)
- New `checks' argument to xr-lint, used to enable these new checks:
  - Detect [+-X] and [X-+] (range to/from '+')
  - Detect [\\t] etc (escape sequences in character alternative)
  - Detect \(:?...\), as a possible typo for \(?:...\)
  - Detect a\|b that could be [ab] which is more efficient
  - Detect effective repetition of repetition such as \(A+B*\)*

Version 1.23
- Represent explicitly the gap in ranges from ASCII to raw bytes:
  "[A-\xbb]" becomes (any "A-\x7f\x80-\xbb") because that is how
  Emacs regexps work. This also suppresses some false positives
  in `xr-lint' and `xr-skip-set-lint'.

Version 1.22
- More compact distribution

Version 1.21
- Suppress false complaint about (? (+ X))

Version 1.20
- Fix duplication removal in character alternatives, like [aaa]
- All diagnostics are now described in the README file
- Improved anchor conflict checks

Version 1.19
- Added filename-specific checks; new PURPOSE argument to `xr-lint'
- Warn about wrapped subsumption, like \(A*C[AB]*\)+
- Improved scope and accuracy of all subsumption checks
- Warn about anchors in conflict with other expressions, like \(A$\)B

Version 1.18
- Fix test broken in Emacs 26

Version 1.17
- Performance improvements

Version 1.16
- Translate [^\n] into nonl
- Better character class subset/superset analysis
- More accurate repetition subsumption check
- Use text quoting for messages

Version 1.15
- Warn about subsuming repetitions in sequence, like [AB]+A*

Version 1.14
- Warn about repetition of grouped repetition

Version 1.13
- More robust pretty-printing, especially for characters
- Generate (category CHAR) for unknown categories

Version 1.12
- Warn about branch subsumption, like [AB]\|A

Version 1.11
- Warn about repetition of empty-matching expressions
- Detect `-' not first or last in char alternatives or skip-sets
- Stronger ad-hoc [...] check in skip-sets

Version 1.10
- Warn about [[:class:]] in skip-sets
- Warn about two-character ranges like [*-+] in regexps

Version 1.9
- Don't complain about [z-a] and [^z-a] specifically
- Improved skip set checks

Version 1.8
- Improved skip set checks

Version 1.7
- Parse skip-sets, adding `xr-skip-set', `xr-skip-set-pp' and
  `xr-skip-set-lint'
- Ad-hoc check for misplaced `]' in regexps

Version 1.6
- Detect duplicated branches like A\|A

Version 1.5
- Add dialect option to `xr' and `xr-pp'
- Negative empty sets, [^z-a], now become `anything'

Version 1.4
- Detect overlap in character alternatives

Version 1.3
- Improved xr-lint warnings

Version 1.2
- `xr-lint' added