ChangeLog for PCRE
------------------

Version 8.33 28-May-2013
--------------------------

1.  Added 'U' to some constants that are compared to unsigned integers, to
    avoid compiler signed/unsigned warnings. Added (int) casts to unsigned
    variables that are added to signed variables, to ensure the result is
    signed and can be negated.

2.  Applied patch by Daniel Richard G for quashing MSVC warnings to the
    CMake config files.

3.  Revise the creation of config.h.generic so that all boolean macros are
    #undefined, whereas non-boolean macros are #ifndef/#endif-ed. This makes
    overriding via -D on the command line possible.

4.  Changing the definition of the variable "op" in pcre_exec.c from pcre_uchar
    to unsigned int is reported to make a quite noticeable speed difference in
    a specific Windows environment. Testing on Linux did also appear to show
    some benefit (and it is clearly not harmful). Also fixed the definition of
    Xop which should be unsigned.

5.  Related to (4), changing the definition of the intermediate variable cc
    in repeated character loops from pcre_uchar to pcre_uint32 also gave speed
    improvements.

6.  Fix forward search in JIT when link size is 3 or greater. Also removed some
    unnecessary spaces.

7.  Adjust autogen.sh and configure.ac to lose warnings given by automake 1.12
    and later.

8.  Fix two buffer over read issues in 16 and 32 bit modes. Affects JIT only.

9.  Optimizing fast_forward_start_bits in JIT.

10. Adding support for callouts in JIT, and fixing some issues revealed
    during this work. Namely:

    (a) Unoptimized capturing brackets incorrectly reset on backtrack.

    (b) Minimum length was not checked before the matching is started.

11. The value of capture_last that is passed to callouts was incorrect in some
    cases when there was a capture on one path that was subsequently abandoned
    after a backtrack. Also, the capture_last value is now reset after a
    recursion, since all captures are also reset in this case.

12. The interpreter no longer returns the "too many substrings" error in the
    case when an overflowing capture is in a branch that is subsequently
    abandoned after a backtrack.

13. In the pathological case when an offset vector of size 2 is used, pcretest
    now prints out the matched string after a yield of 0 or 1.

14. Inlining subpatterns in recursions, when certain conditions are fulfilled.
    Only supported by the JIT compiler at the moment.

15. JIT compiler now supports 32 bit Macs thanks to Lawrence Velazquez.

16. Partial matches now set offsets[2] to the "bumpalong" value, that is, the
    offset of the starting point of the matching process, provided the offsets
    vector is large enough.

17. The \A escape now records a lookbehind value of 1, though its execution
    does not actually inspect the previous character. This is to ensure that,
    in partial multi-segment matching, at least one character from the old
    segment is retained when a new segment is processed. Otherwise, if there
    are no lookbehinds in the pattern, \A might match incorrectly at the start
    of a new segment.

18. Added some #ifdef __VMS code into pcretest.c to help VMS implementations.

19. Redefined some pcre_uchar variables in pcre_exec.c as pcre_uint32; this
    gives some modest performance improvement in 8-bit mode.

20. Added the PCRE-specific property \p{Xuc} for matching characters that can
    be expressed in certain programming languages using Universal Character
    Names.

21. Unicode validation has been updated in the light of Unicode Corrigendum #9,
    which points out that "non characters" are not "characters that may not
    appear in Unicode strings" but rather "characters that are reserved for
    internal use and have only local meaning".

22. When a pattern was compiled with automatic callouts (PCRE_AUTO_CALLOUT) and
    there was a conditional group that depended on an assertion, if the
    assertion was false, the callout that immediately followed the alternation
    in the condition was skipped when pcre_exec() was used for matching.

23. Allow an explicit callout to be inserted before an assertion that is the
    condition for a conditional group, for compatibility with automatic
    callouts, which always insert a callout at this point.

24. In 8.31, (*COMMIT) was confined to within a recursive subpattern. Perl also
    confines (*SKIP) and (*PRUNE) in the same way, and this has now been done.

25. (*PRUNE) is now supported by the JIT compiler.

26. Fix infinite loop when /(?<=(*SKIP)ac)a/ is matched against aa.

27. Fix the case where there are two or more SKIPs with arguments that may be
    ignored.

28. (*SKIP) is now supported by the JIT compiler.

29. (*THEN) is now supported by the JIT compiler.

30. Update RunTest with additional test selector options.

31. The way PCRE handles backtracking verbs has been changed in two ways.

    (1) Previously, in something like (*COMMIT)(*SKIP), COMMIT would override
    SKIP. Now, PCRE acts on whichever backtracking verb is reached first by
    backtracking. In some cases this makes it more Perl-compatible, but Perl's
    rather obscure rules do not always do the same thing.

    (2) Previously, backtracking verbs were confined within assertions. This is
    no longer the case for positive assertions, except for (*ACCEPT). Again,
    this sometimes improves Perl compatibility, and sometimes does not.

32. A number of tests that were in test 2 because Perl did things differently
    have been moved to test 1, because either Perl or PCRE has changed, and
    these tests are now compatible.

32. Backtracking control verbs are now handled in the same way in JIT and
    interpreter.

33. An opening parenthesis in a MARK/PRUNE/SKIP/THEN name in a pattern that
    contained a forward subroutine reference caused a compile error.

34. Auto-detect and optimize limited repetitions in JIT.

35. Implement PCRE_NEVER_UTF to lock out the use of UTF, in particular,
    blocking (*UTF) etc.

36. In the interpreter, maximizing pattern repetitions for characters and
    character types now use tail recursion, which reduces stack usage.

37. The value of the max lookbehind was not correctly preserved if a compiled
    and saved regex was reloaded on a host of different endianness.

38. Implemented (*LIMIT_MATCH) and (*LIMIT_RECURSION). As part of the extension
    of the compiled pattern block, expand the flags field from 16 to 32 bits
    because it was almost full.

39. Try madvise first before posix_madvise.

40. Change 7 for PCRE 7.9 made it impossible for pcregrep to find empty lines
    with a pattern such as ^$. It has taken 4 years for anybody to notice! The
    original change locked out all matches of empty strings. This has been
    changed so that one match of an empty string per line is recognized.
    Subsequent searches on the same line (for colouring or for --only-matching,
    for example) do not recognize empty strings.

41. Applied a user patch to fix a number of spelling mistakes in comments.

42. Data lines longer than 65536 caused pcretest to crash.

43. Clarified the data type for length and startoffset arguments for pcre_exec
    and pcre_dfa_exec in the function-specific man pages, where they were
    explicitly stated to be in bytes, never having been updated. I also added
    some clarification to the pcreapi man page.

44. A call to pcre_dfa_exec() with an output vector size less than 2 caused
    a segmentation fault.


Version 8.32 30-November-2012
-----------------------------

1.  Improved JIT compiler optimizations for first character search and single
    character iterators.

2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
    Patch by Daniel Richard G.

3.  Single character iterator optimizations in the JIT compiler.

4.  Improved JIT compiler optimizations for character ranges.

5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
    Reported by Giuseppe D'Angelo.

6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
    of a line, was being set incorrectly in cases where .* appeared inside
    atomic brackets at the start of a pattern, or where there was a subsequent
    *PRUNE or *SKIP.

7.  Improved instruction cache flush for POWER/PowerPC.
    Patch by Daniel Richard G.

8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
    grep:

    (a) There is now no limit to the number of patterns to be matched.

    (b) An error is given if a pattern is too long.

    (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
        are now supported.

    (d) --exclude-from and --include-from (multiple use) have been added.

    (e) Exclusions and inclusions now apply to all files and directories, not
        just to those obtained from scanning a directory recursively.

    (f) Multiple uses of -f and --file-list are now supported.

    (g) In a Windows environment, the default for -d has been changed from
        "read" (the GNU grep default) to "skip", because otherwise the presence
        of a directory in the file list provokes an error.

    (h) The documentation has been revised and clarified in places.

9.  Improve the matching speed of capturing brackets.

10. Changed the meaning of \X so that it now matches a Unicode extended
    grapheme cluster.

11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
    out POSIX threads when JIT support is configured.

12. Added support for PCRE_STUDY_EXTRA_NEEDED.

13. In the POSIX wrapper regcomp() function, setting re_nsub field in the preg
    structure could go wrong in environments where size_t is not the same size
    as int.

14. Applied user-supplied patch to pcrecpp.cc to allow PCRE_NO_UTF8_CHECK to be
    set.

15. The EBCDIC support had decayed; later updates to the code had included
    explicit references to (e.g.) \x0a instead of CHAR_LF. There has been a
    general tidy up of EBCDIC-related issues, and the documentation was also
    not quite right. There is now a test that can be run on ASCII systems to
    check some of the EBCDIC-related things (but is it not a full test).

16. The new PCRE_STUDY_EXTRA_NEEDED option is now used by pcregrep, resulting
    in a small tidy to the code.

17. Fix JIT tests when UTF is disabled and both 8 and 16 bit mode are enabled.

18. If the --only-matching (-o) option in pcregrep is specified multiple
    times, each one causes appropriate output. For example, -o1 -o2 outputs the
    substrings matched by the 1st and 2nd capturing parentheses. A separating
    string can be specified by --om-separator (default empty).

19. Improving the first n character searches.

20. Turn case lists for horizontal and vertical white space into macros so that
    they are defined only once.

21. This set of changes together give more compatible Unicode case-folding
    behaviour for characters that have more than one other case when UCP
    support is available.

    (a) The Unicode property table now has offsets into a new table of sets of
        three or more characters that are case-equivalent. The MultiStage2.py
        script that generates these tables (the pcre_ucd.c file) now scans
        CaseFolding.txt instead of UnicodeData.txt for character case
        information.

    (b) The code for adding characters or ranges of characters to a character
        class has been abstracted into a generalized function that also handles
        case-independence. In UTF-mode with UCP support, this uses the new data
        to handle characters with more than one other case.

    (c) A bug that is fixed as a result of (b) is that codepoints less than 256
        whose other case is greater than 256 are now correctly matched
        caselessly. Previously, the high codepoint matched the low one, but not
        vice versa.

    (d) The processing of \h, \H, \v, and \ in character classes now makes use
        of the new class addition function, using character lists defined as
        macros alongside the case definitions of 20 above.

    (e) Caseless back references now work with characters that have more than
        one other case.

    (f) General caseless matching of characters with more than one other case
        is supported.

22. Unicode character properties were updated from Unicode 6.2.0

23. Improved CMake support under Windows. Patch by Daniel Richard G.

24. Add support for 32-bit character strings, and UTF-32

25. Major JIT compiler update (code refactoring and bugfixing).
    Experimental Sparc 32 support is added.

26. Applied a modified version of Daniel Richard G's patch to create
    pcre.h.generic and config.h.generic by "make" instead of in the
    PrepareRelease script.

27. Added a definition for CHAR_NULL (helpful for the z/OS port), and use it in
    pcre_compile.c when checking for a zero character.

28. Introducing a native interface for JIT. Through this interface, the compiled
    machine code can be directly executed. The purpose of this interface is to
    provide fast pattern matching, so several sanity checks are not performed.
    However, feature tests are still performed. The new interface provides
    1.4x speedup compared to the old one.

29. If pcre_exec() or pcre_dfa_exec() was called with a negative value for
    the subject string length, the error given was PCRE_ERROR_BADOFFSET, which
    was confusing. There is now a new error PCRE_ERROR_BADLENGTH for this case.

30. In 8-bit UTF-8 mode, pcretest failed to give an error for data codepoints
    greater than 0x7fffffff (which cannot be represented in UTF-8, even under
    the "old" RFC 2279). Instead, it ended up passing a negative length to
    pcre_exec().

31. Add support for GCC's visibility feature to hide internal functions.

32. Running "pcretest -C pcre8" or "pcretest -C pcre16" gave a spurious error
    "unknown -C option" after outputting 0 or 1.

33. There is now support for generating a code coverage report for the test
    suite in environments where gcc is the compiler and lcov is installed. This
    is mainly for the benefit of the developers.

34. If PCRE is built with --enable-valgrind, certain memory regions are marked
    unaddressable using valgrind annotations, allowing valgrind to detect
    invalid memory accesses. This is mainly for the benefit of the developers.

25. (*UTF) can now be used to start a pattern in any of the three libraries.

26. Give configure error if --enable-cpp but no C++ compiler found.


Version 8.31 06-July-2012
-------------------------

1.  Fixing a wrong JIT test case and some compiler warnings.

2.  Removed a bashism from the RunTest script.

3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
    to unsigned type, result still unsigned" that was given by an MS compiler
    on encountering the code "-sizeof(xxx)".

4.  Partial matching support is added to the JIT compiler.

5.  Fixed several bugs concerned with partial matching of items that consist
    of more than one character:

    (a) /^(..)\1/ did not partially match "aba" because checking references was
        done on an "all or nothing" basis. This also applied to repeated
        references.

    (b) \R did not give a hard partial match if \r was found at the end of the
        subject.

    (c) \X did not give a hard partial match after matching one or more
        characters at the end of the subject.

    (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
        a partial match for the string "\r".

    (e) When newline was set to CRLF, the metacharacter "." did not recognize
        a partial match for a CR character at the end of the subject string.

6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
    running pcretest, the text "(JIT)" added to the output whenever JIT is
    actually used to run the match.

7.  Individual JIT compile options can be set in pcretest by following -s+[+]
    or /S+[+] with a digit between 1 and 7.

8.  OP_NOT now supports any UTF character not just single-byte ones.

9.  (*MARK) control verb is now supported by the JIT compiler.

10. The command "./RunTest list" lists the available tests without actually
    running any of them. (Because I keep forgetting what they all are.)

11. Add PCRE_INFO_MAXLOOKBEHIND.

12. Applied a (slightly modified) user-supplied patch that improves performance
    when the heap is used for recursion (compiled with --disable-stack-for-
    recursion). Instead of malloc and free for each heap frame each time a
    logical recursion happens, frames are retained on a chain and re-used where
    possible. This sometimes gives as much as 30% improvement.

13. As documented, (*COMMIT) is now confined to within a recursive subpattern
    call.

14. As documented, (*COMMIT) is now confined to within a positive assertion.

15. It is now possible to link pcretest with libedit as an alternative to
    libreadline.

16. (*COMMIT) control verb is now supported by the JIT compiler.

17. The Unicode data tables have been updated to Unicode 6.1.0.

18. Added --file-list option to pcregrep.

19. Added binary file support to pcregrep, including the -a, --binary-files,
    -I, and --text options.

20. The madvise function is renamed for posix_madvise for QNX compatibility
    reasons. Fixed by Giuseppe D'Angelo.

21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.

22. Changed the option for creating symbolic links for 16-bit man pages from
    -s to -sf so that re-installing does not cause issues.

23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.

24. Fixed a very old bug in pcretest that caused errors with restarted DFA
    matches in certain environments (the workspace was not being correctly
    retained). Also added to pcre_dfa_exec() a simple plausibility check on
    some of the workspace data at the beginning of a restart.

25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
    was not doing so when it should - probably a typo introduced by SVN 528
    (change 8.10/14).

26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
    \w+ when the character tables indicated that \x{c4} was a word character.
    There were several related cases, all because the tests for doing a table
    lookup were testing for characters less than 127 instead of 255.

27. If a pattern contains capturing parentheses that are not used in a match,
    their slots in the ovector are set to -1. For those that are higher than
    any matched groups, this happens at the end of processing. In the case when
    there were back references that the ovector was too small to contain
    (causing temporary malloc'd memory to be used during matching), and the
    highest capturing number was not used, memory off the end of the ovector
    was incorrectly being set to -1. (It was using the size of the temporary
    memory instead of the true size.)

28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
    ovector size, it uses memory at the end of the block that it has got.

29. Check for an overlong MARK name and give an error at compile time. The
    limit is 255 for the 8-bit library and 65535 for the 16-bit library.

30. JIT compiler update.

31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
    Rill for the patch.

32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.

33. Variable renamings in the PCRE-JIT compiler. No functionality change.

34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
    SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
    was enabled.

35. Improve JIT code generation for greedy plus quantifier.

36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
    1 to "aa" instead of to an empty string. The bug affected repeated groups
    that could potentially match an empty string.

37. Optimizing single character iterators in JIT.

38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
    the same checks as \x{...} characters in non-JavaScript mode. Specifically,
    codepoints that are too big for the mode are faulted, and in a UTF mode,
    disallowed codepoints are also faulted.

39. If PCRE was compiled with UTF support, in three places in the DFA
    matcher there was code that should only have been obeyed in UTF mode, but
    was being obeyed unconditionally. In 8-bit mode this could cause incorrect
    processing when bytes with values greater than 127 were present. In 16-bit
    mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
    both cases the values are those that cannot be the first data item in a UTF
    character. The three items that might have provoked this were recursions,
    possessively repeated groups, and atomic groups.

40. Ensure that libpcre is explicitly listed in the link commands for pcretest
    and pcregrep, because some OS require shared objects to be explicitly
    passed to ld, causing the link step to fail if they are not.

41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
    mode, patterns that started with \h* or \R* might be incorrectly matched.


Version 8.30 04-February-2012
-----------------------------

1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
    name is defined in ctype.h.

2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
    only in quite long subpatterns.

3.  Removed the function pcre_info(), which has been obsolete and deprecated
    since it was replaced by pcre_fullinfo() in February 2000.

4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
    match a (*MARK), and the match failed at the start of the subject, a
    reference to memory before the start of the subject could occur. This bug
    was introduced by fix 17 of release 8.21.

5.  A reference to an unset group with zero minimum repetition was giving
    totally wrong answers (in non-JavaScript-compatibility mode). For example,
    /(another)?(\1?)test/ matched against "hello world test". This bug was
    introduced in release 8.13.

6.  Add support for 16-bit character strings (a large amount of work involving
    many changes and refactorings).

7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
    command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
    from a file.

8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
    rounding is not applied in this particular case).

9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
    if they appear, or are escaped, in patterns.

10. Get rid of a number of -Wunused-but-set-variable warnings.

11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
    "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
    Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
    also returns the mark "x". This bug applied to capturing parentheses,
    non-capturing parentheses, and atomic parentheses. It also applied to some
    assertions.

12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
    information out of configure.ac instead of relying on pcre.h.generic, which
    is not stored in the repository.

13. Applied Dmitry V. Levin's patch for a more portable method for linking with
    -lreadline.

14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.

15. Applied Graycode's patch to put the top-level frame on the stack rather
    than the heap when not using the stack for recursion. This gives a
    performance improvement in many cases when recursion is not deep.

16. Experimental code added to "pcretest -C" to output the stack frame size.


Version 8.21 12-Dec-2011
------------------------

1.  Updating the JIT compiler.

2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
    are added as well.

3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
    PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
    calling _pcre_jit_exec. Some extra comments are added.

4.  (*MARK) settings inside atomic groups that do not contain any capturing
    parentheses, for example, (?>a(*:m)), were not being passed out. This bug
    was introduced by change 18 for 8.20.

5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
    ECMA-262 standard.

6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
    erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
    This bug was probably introduced by change 9 of 8.13.

7.  While fixing 6 above, I noticed that a number of other items were being
    incorrectly rejected as "not fixed length". This arose partly because newer
    opcodes had not been added to the fixed-length checking code. I have (a)
    corrected the bug and added tests for these items, and (b) arranged for an
    error to occur if an unknown opcode is encountered while checking for fixed
    length instead of just assuming "not fixed length". The items that were
    rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
    (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
    repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.

8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
    being incorrectly compiled and would have given unpredicatble results.

9.  A possessively repeated subpattern with minimum repeat count greater than
    one behaved incorrectly. For example, (A){2,}+ behaved as if it was
    (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
    the first (A) could occur when it should not.

10. Add a cast and remove a redundant test from the code.

11. JIT should use pcre_malloc/pcre_free for allocation.

12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
    best practice nowadays, and helps with cross-compiling. (If the exec_prefix
    is anything other than /usr, -L is still shown).

13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.

14. Perl does not support \N without a following name in a [] class; PCRE now
    also gives an error.

15. If a forward reference was repeated with an upper limit of around 2000,
    it caused the error "internal error: overran compiling workspace". The
    maximum number of forward references (including repeats) was limited by the
    internal workspace, and dependent on the LINK_SIZE. The code has been
    rewritten so that the workspace expands (via pcre_malloc) if necessary, and
    the default depends on LINK_SIZE. There is a new upper limit (for safety)
    of around 200,000 forward references. While doing this, I also speeded up
    the filling in of repeated forward references.

16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
    incorrectly expecting the subject to contain another "a" after the start.

17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
    in the match, the SKIP should be ignored. This was not happening; instead
    the SKIP was being treated as NOMATCH. For patterns such as
    /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
    tested.

18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
    now much more compatible with Perl, in particular in cases where the result
    is a non-match for a non-anchored pattern. For example, if
    /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
    "m", where previously it did not return a name. A side effect of this
    change is that for partial matches, the last encountered mark name is
    returned, as for non matches. A number of tests that were previously not
    Perl-compatible have been moved into the Perl-compatible test files. The
    refactoring has had the pleasing side effect of removing one argument from
    the match() function, thus reducing its stack requirements.

19. If the /S+ option was used in pcretest to study a pattern using JIT,
    subsequent uses of /S (without +) incorrectly behaved like /S+.

21. Retrieve executable code size support for the JIT compiler and fixing
    some warnings.

22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
    not work when the shorter character appeared right at the end of the
    subject string.

23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
    systems.

24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
    output it when the /M option is used in pcretest.

25. The CheckMan script was not being included in the distribution. Also, added
    an explicit "perl" to run Perl scripts from the PrepareRelease script
    because this is reportedly needed in Windows.

26. If study data was being save in a file and studying had not found a set of
    "starts with" bytes for the pattern, the data written to the file (though
    never used) was taken from uninitialized memory and so caused valgrind to
    complain.

27. Updated RunTest.bat as provided by Sheri Pierce.

28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.

29. Computation of memory usage for the table of capturing group names was
    giving an unnecessarily large value.


Version 8.20 21-Oct-2011
------------------------

1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
    a POSIX class. After further experiments with Perl, which convinced me that
    Perl has bugs and confusions, a closing square bracket is no longer allowed
    in a POSIX name. This bug also affected patterns with classes that started
    with full stops.

2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
    captured substring, but while checking the failing first alternative,
    substring 1 is temporarily captured. If the output vector supplied to
    pcre_exec() was not big enough for this capture, the yield of the function
    was still zero ("insufficient space for captured substrings"). This cannot
    be totally fixed without adding another stack variable, which seems a lot
    of expense for a edge case. However, I have improved the situation in cases
    such as /(a)(b)x|abc/ matched against "abc", where the return code
    indicates that fewer than the maximum number of slots in the ovector have
    been set.

3.  Related to (2) above: when there are more back references in a pattern than
    slots in the output vector, pcre_exec() uses temporary memory during
    matching, and copies in the captures as far as possible afterwards. It was
    using the entire output vector, but this conflicts with the specification
    that only 2/3 is used for passing back captured substrings. Now it uses
    only the first 2/3, for compatibility. This is, of course, another edge
    case.

4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
    main code base, and can be used by building with --enable-jit. When this is
    done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
    runtime --no-jit option is given.

5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
    ovector, the return from the function was zero, implying that there were
    other matches that did not fit. The correct "exactly full" value is now
    returned.

6.  If a subpattern that was called recursively or as a subroutine contained
    (*PRUNE) or any other control that caused it to give a non-standard return,
    invalid errors such as "Error -26 (nested recursion at the same subject
    position)" or even infinite loops could occur.

7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
    computing the minimum length on reaching *ACCEPT, and so ended up with the
    wrong value of 1 rather than 0. Further investigation indicates that
    computing a minimum subject length in the presence of *ACCEPT is difficult
    (think back references, subroutine calls), and so I have changed the code
    so that no minimum is registered for a pattern that contains *ACCEPT.

8.  If (*THEN) was present in the first (true) branch of a conditional group,
    it was not handled as intended. [But see 16 below.]

9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
    Sheri Pierce.

10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
    the first byte in a match must be "a".

11. Change 17 for 8.13 increased the recursion depth for patterns like
    /a(?:.)*?a/ drastically. I've improved things by remembering whether a
    pattern contains any instances of (*THEN). If it does not, the old
    optimizations are restored. It would be nice to do this on a per-group
    basis, but at the moment that is not feasible.

12. In some environments, the output of pcretest -C is CRLF terminated. This
    broke RunTest's code that checks for the link size. A single white space
    character after the value is now allowed for.

13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
    For "fr", it uses the Windows-specific input and output files.

14. If (*THEN) appeared in a group that was called recursively or as a
    subroutine, it did not work as intended. [But see next item.]

15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
    pattern fragments (but not containing any | characters). If A and B are
    matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
    was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
    D. In other words, Perl considers parentheses that do not contain any |
    characters to be part of a surrounding alternative, whereas PCRE was
    treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
    differently. PCRE now behaves in the same way as Perl, except in the case
    of subroutine/recursion calls such as (?1) which have in any case always
    been different (but PCRE had them first :-).

16. Related to 15 above: Perl does not treat the | in a conditional group as
    creating alternatives. Such a group is treated in the same way as an
    ordinary group without any | characters when processing (*THEN). PCRE has
    been changed to match Perl's behaviour.

17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
    RunGrepTest script failed.

18. Change 22 for version 13 caused atomic groups to use more stack. This is
    inevitable for groups that contain captures, but it can lead to a lot of
    stack use in large patterns. The old behaviour has been restored for atomic
    groups that do not contain any capturing parentheses.

19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
    suppress the check for a minimum subject length at run time. (If it was
    given to pcre_exec() or pcre_dfa_exec() it did work.)

20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
    fail to work when decoding hex characters in data strings in EBCDIC
    environments.

21. It appears that in at least one Mac OS environment, the isxdigit() function
    is implemented as a macro that evaluates to its argument more than once,
    contravening the C 90 Standard (I haven't checked a later standard). There
    was an instance in pcretest which caused it to go wrong when processing
    \x{...} escapes in subject strings. The has been rewritten to avoid using
    things like p++ in the argument of isxdigit().


Version 8.13 16-Aug-2011
------------------------

1.  The Unicode data tables have been updated to Unicode 6.0.0.

2.  Two minor typos in pcre_internal.h have been fixed.

3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
    pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
    in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).

4.  There were a number of related bugs in the code for matching backrefences
    caselessly in UTF-8 mode when codes for the characters concerned were
    different numbers of bytes. For example, U+023A and U+2C65 are an upper
    and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
    (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
    code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
    2-byte code at the end of the subject (it thought there wasn't enough data
    left).

5.  Comprehensive information about what went wrong is now returned by
    pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
    as the output vector has at least 2 elements. The offset of the start of
    the failing character and a reason code are placed in the vector.

6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
    now returned is for the first byte of the failing character, instead of the
    last byte inspected. This is an incompatible change, but I hope it is small
    enough not to be a problem. It makes the returned offset consistent with
    pcre_exec() and pcre_dfa_exec().

7.  pcretest now gives a text phrase as well as the error number when
    pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
    failure, the offset and reason code are output.

8.  When \R was used with a maximizing quantifier it failed to skip backwards
    over a \r\n pair if the subsequent match failed. Instead, it just skipped
    back over a single character (\n). This seems wrong (because it treated the
    two characters as a single entity when going forwards), conflicts with the
    documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
    behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
    has been changed.

9.  Some internal refactoring has changed the processing so that the handling
    of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
    time (the PCRE_DOTALL option was changed this way some time ago: version
    7.7 change 16). This has made it possible to abolish the OP_OPT op code,
    which was always a bit of a fudge. It also means that there is one less
    argument for the match() function, which reduces its stack requirements
    slightly. This change also fixes an incompatibility with Perl: the pattern
    (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.

10. More internal refactoring has drastically reduced the number of recursive
    calls to match() for possessively repeated groups such as (abc)++ when
    using pcre_exec().

11. While implementing 10, a number of bugs in the handling of groups were
    discovered and fixed:

    (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
    (a|)*(?1) gave a compile-time internal error.
    ((a|)+)+  did not notice that the outer group could match an empty string.
    (^a|^)+   was not marked as anchored.
    (.*a|.*)+ was not marked as matching at start or after a newline.

12. Yet more internal refactoring has removed another argument from the match()
    function. Special calls to this function are now indicated by setting a
    value in a variable in the "match data" data block.

13. Be more explicit in pcre_study() instead of relying on "default" for
    opcodes that mean there is no starting character; this means that when new
    ones are added and accidentally left out of pcre_study(), testing should
    pick them up.

14. The -s option of pcretest has been documented for ages as being an old
    synonym of -m (show memory usage). I have changed it to mean "force study
    for every regex", that is, assume /S for every regex. This is similar to -i
    and -d etc. It's slightly incompatible, but I'm hoping nobody is still
    using it. It makes it easier to run collections of tests with and without
    study enabled, and thereby test pcre_study() more easily. All the standard
    tests are now run with and without -s (but some patterns can be marked as
    "never study" - see 20 below).

15. When (*ACCEPT) was used in a subpattern that was called recursively, the
    restoration of the capturing data to the outer values was not happening
    correctly.

16. If a recursively called subpattern ended with (*ACCEPT) and matched an
    empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
    pattern had matched an empty string, and so incorrectly returned a no
    match.

17. There was optimizing code for the last branch of non-capturing parentheses,
    and also for the obeyed branch of a conditional subexpression, which used
    tail recursion to cut down on stack usage. Unfortunately, now that there is
    the possibility of (*THEN) occurring in these branches, tail recursion is
    no longer possible because the return has to be checked for (*THEN). These
    two optimizations have therefore been removed. [But see 8.20/11 above.]

18. If a pattern containing \R was studied, it was assumed that \R always
    matched two bytes, thus causing the minimum subject length to be
    incorrectly computed because \R can also match just one byte.

19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
    was incorrectly computed.

20. If /S is present twice on a test pattern in pcretest input, it now
    *disables* studying, thereby overriding the use of -s on the command line
    (see 14 above). This is necessary for one or two tests to keep the output
    identical in both cases.

21. When (*ACCEPT) was used in an assertion that matched an empty string and
    PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.

22. When an atomic group that contained a capturing parenthesis was
    successfully matched, but the branch in which it appeared failed, the
    capturing was not being forgotten if a higher numbered group was later
    captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
    group 1 to "a", when in fact it should be unset. This applied to multi-
    branched capturing and non-capturing groups, repeated or not, and also to
    positive assertions (capturing in negative assertions does not happen
    in PCRE) and also to nested atomic groups.

23. Add the ++ qualifier feature to pcretest, to show the remainder of the
    subject after a captured substring, to make it easier to tell which of a
    number of identical substrings has been captured.

24. The way atomic groups are processed by pcre_exec() has been changed so that
    if they are repeated, backtracking one repetition now resets captured
    values correctly. For example, if ((?>(a+)b)+aabab) is matched against
    "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
    "aaa". Previously, it would have been "a". As part of this code
    refactoring, the way recursive calls are handled has also been changed.

25. If an assertion condition captured any substrings, they were not passed
    back unless some other capturing happened later. For example, if
    (?(?=(a))a) was matched against "a", no capturing was returned.

26. When studying a pattern that contained subroutine calls or assertions,
    the code for finding the minimum length of a possible match was handling
    direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
    group 1 called group 2 while simultaneously a separate group 2 called group
    1). A stack overflow occurred in this case. I have fixed this by limiting
    the recursion depth to 10.

27. Updated RunTest.bat in the distribution to the version supplied by Tom
    Fortmann. This supports explicit test numbers on the command line, and has
    argument validation and error reporting.

28. An instance of \X with an unlimited repeat could fail if at any point the
    first character it looked at was a mark character.

29. Some minor code refactoring concerning Unicode properties and scripts
    should reduce the stack requirement of match() slightly.

30. Added the '=' option to pcretest to check the setting of unused capturing
    slots at the end of the pattern, which are documented as being -1, but are
    not included in the return count.

31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
    compiled something random. Now it gives a compile-time error (as does
    Perl).

32. A *MARK encountered during the processing of a positive assertion is now
    recorded and passed back (compatible with Perl).

33. If --only-matching or --colour was set on a pcregrep call whose pattern
    had alternative anchored branches, the search for a second match in a line
    was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
    matched the line "0102" twice. The same bug affected patterns that started
    with a backwards assertion. For example /\b01|\b02/ also matched "0102"
    twice.

34. Previously, PCRE did not allow quantification of assertions. However, Perl
    does, and because of capturing effects, quantifying parenthesized
    assertions may at times be useful. Quantifiers are now allowed for
    parenthesized assertions.

35. A minor code tidy in pcre_compile() when checking options for \R usage.

36. \g was being checked for fancy things in a character class, when it should
    just be a literal "g".

37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
    appearance of a nested POSIX class supersedes an apparent external class.
    For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
    unescaped square brackets may also appear as part of class names. For
    example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
    more like Perl. (But see 8.20/1 above.)

38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
    was because it thought it was \N{name}, which is not supported).

39. Add minix to OS list not supporting the -S option in pcretest.

40. PCRE tries to detect cases of infinite recursion at compile time, but it
    cannot analyze patterns in sufficient detail to catch mutual recursions
    such as ((?1))((?2)). There is now a runtime test that gives an error if a
    subgroup is called recursively as a subpattern for a second time at the
    same position in the subject string. In previous releases this might have
    been caught by the recursion limit, or it might have run out of stack.

41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
    happen only once. PCRE was, however incorrectly giving a compile time error
    "recursive call could loop indefinitely" because it cannot analyze the
    pattern in sufficient detail. The compile time test no longer happens when
    PCRE is compiling a conditional subpattern, but actual runaway loops are
    now caught at runtime (see 40 above).

42. It seems that Perl allows any characters other than a closing parenthesis
    to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
    has been changed to be the same.

43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
    as not to get warnings when autogen.sh is called. Also changed
    AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).

44. To help people who use pcregrep to scan files containing exceedingly long
    lines, the following changes have been made:

    (a) The default value of the buffer size parameter has been increased from
        8K to 20K. (The actual buffer used is three times this size.)
[--snip--]
