Log Message:
re2c: update to 3.0.

3.0 (2022-01-27)
~~~~~~~~~~~~~~~~

- Added code generation backend for Rust:

  + Enabled with ``--lang rust`` option.
  + A new ``re2rust`` binary (built by default, or configured with
    ``--enable-rust`` Autoconf option and ``RE2C_BUILD_RE2RUST`` CMake option).

- Added options:

  + ``--loop-switch``
  + ``--no-unsafe``

- Added configurations;

  + ``re2c:label:yyloop``
  + ``re2c:unsafe``

- Renamed options to use common naming scheme. The old names are supported as
  aliases, so the change does not break existing code. Documentation has been
  updated to use new names.

  + ``--api`` is a new alias for ``--input``
  + ``--ebcdic`` is a new alias for ``--ecb``
  + ``--ucs2`` is a new alias for ``--wide-chars``
  + ``--utf32`` is a new alias for ``--unicode``
  + ``--utf16`` is a new alias for ``--utf-16``
  + ``--utf8`` is a new alias for ``--utf-8``
  + ``--header`` is a new alias for ``--type-header``

- Renamed configurations to use common naming scheme and support proper scoping
  under subcategories such as ``:define``, ``:label``, ``:variable``, etc. The
  old names are supported as aliases, so the change does not break existing
  code. Documentation has been updated to use new names.

  + ``re2c:api`` is a new alias for ``re2c:flags:input``
  + ``re2c:bit-vectors`` is a new alias for ``re2c:flags:bit-vectors``
  + ``re2c:case-insensitive`` is a new alias for ``re2c:flags:case-insensitive``
  + ``re2c:case-inverted`` is a new alias for ``re2c:flags:case-inverted``
  + ``re2c:case-ranges`` is a new alias for ``re2c:flags:case-ranges``
  + ``re2c:cond:prefix`` is a new alias for ``re2c:condprefix``
  + ``re2c:cond:enumprefix`` is a new alias for ``re2c:condenumprefix``
  + ``re2c:computed-gotos`` is a new alias for ``re2c:flags:computed-gotos``
  + ``re2c:computed-gotos:threshold`` is a new alias for ``re2c:cgoto:threshold``
  + ``re2c:debug-output`` is a new alias for ``re2c:flags:debug-output``
  + ``re2c:encoding:ebcdic`` is a new alias for ``re2c:flags:ecb``
  + ``re2c:encoding:utf32`` is a new alias for ``re2c:flags:unicode``
  + ``re2c:encoding:ucs2`` is a new alias for ``re2c:flags:wide-chars``
  + ``re2c:encoding:utf16`` is a new alias for ``re2c:flags:utf-16``
  + ``re2c:encoding:utf8`` is a new alias for ``re2c:flags:utf-8``
  + ``re2c:encoding-policy`` is a new alias for ``re2c:flags:encoding-policy``
  + ``re2c:empty-class`` is a new alias for ``re2c:flags:empty-class``
  + ``re2c:header`` is a new alias for ``re2c:flags:type-header``
  + ``re2c:label:prefix`` is a new alias for ``re2c:labelprefix``
  + ``re2c:label:yyfill`` is a new alias for ``re2c:label:yyFillLabel``
  + ``re2c:label:start`` is a new alias for ``re2c:startlabel``
  + ``re2c:nested-ifs`` is a new alias for ``re2c:flags:nested-ifs``
  + ``re2c:posix-captures`` is a new alias for ``re2c:flags:posix-captures``
  + ``re2c:tags`` is a new alias for ``re2c:flags:tags``
  + ``re2c:variable:yych:conversion`` is a new alias for ``re2c:yych:conversion``
  + ``re2c:variable:yych:emit`` is a new alias for ``re2c:yych:emit``
  + ``re2c:variable:yybm:hex`` is a new alias for ``re2c:yybm:hex``
  + ``re2c:unsafe`` is a new alias for ``re2c:flags:unsafe``

- Added directive alias ``conditions:re2c`` for ``types:re2c``.

- Multiple small changes in code generation, including some formatting changes
  that result in large diffs in the generated code:

  + Do not allocate indices for unused state labels (this results in a change in
    state enumeration), commits
    `919570c4 <https://github.com/skvadrik/re2c/commit/919570c4>`_ and
    `82b704f6 <https://github.com/skvadrik/re2c/commit/82b704f6>`_.
  + Do not generate redundant ``YYPEEK`` statements, commit
    `cca31d22 <https://github.com/skvadrik/re2c/commit/cca31d22>`_.
  + Do not generate ``YYDEBUG`` statements for unused states labels, commit
    `a46f01e6 <https://github.com/skvadrik/re2c/commit/a46f01e6>`_.
  + C backend: change formatting of switch statements, commit
    `ed88e12e <https://github.com/skvadrik/re2c/commit/ed88e12e>`_.
  + Go backend: render continuous character ranges in compact form, commit
    `09161b14 <https://github.com/skvadrik/re2c/commit/09161b14>`_.
  + Mark start and end of included .re files with line directives, commit
    `48e83fca <https://github.com/skvadrik/re2c/commit/48e83fca>`_.

- A fix to limit maximum allowed NFA and DFA size (to avoid out of memory
  crashes and stack overflows), commit
  `a3473fd7 <https://github.com/skvadrik/re2c/commit/a3473fd7>`_.

- A fix to correctly compute fixed tags in trailing context, commit
  `68e1ab71 <https://github.com/skvadrik/re2c/commit/68e1ab71>`_.

- A fix to generate non-overlapping names for s-tag and m-tag variables, commit
  `7c6b5c95 <https://github.com/skvadrik/re2c/commit/7c6b5c95>`_.

- Infrastructural: added support for CMake presets.

- Updated documentation.

- Backwards-incompatible changes that are unlikely to affect any users:

  + Restrict lexical contexts where ``%{`` is recognized as a block start,
    commit `dba7d055 <https://github.com/skvadrik/re2c/commit/dba7d055>`_.
  + Emit an error when repetition lower bound exceeds upper bound, commit
    `039c1894 <https://github.com/skvadrik/re2c/commit/039c1894>`_.