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-revision 459 by ph10,
Sun Oct  4 09:21:39 2009 UTC
+revision 742 by zherczeg,
Sun Nov  6 08:05:33 2011 UTC
 Line 1
  ChangeLog for PCRE
  ------------------
- Version 8.00 ??-???-??
+ Version 8.21
+ ------------
+.  Updating the JIT compiler.
+.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
+     are added as well.
+.  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.
+ Version 8.20 21-Oct-2011
+ ------------------------
+.  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.
+.  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.
+.  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.
+.  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.
+.  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.
+.  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.
+.  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.
+.  If (*THEN) was present in the first (true) branch of a conditional group,
+     it was not handled as intended. [But see 16 below.]
+.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
+     Sheri Pierce.
+. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
+     the first byte in a match must be "a".
+. 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.
+. 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.
+. 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.
+. If (*THEN) appeared in a group that was called recursively or as a
+     subroutine, it did not work as intended. [But see next item.]
+. 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 :-).
+. 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.
+. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
+     RunGrepTest script failed.
+. 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.
+. 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.)
+. 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.
+. 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
+ ------------------------
+.  The Unicode data tables have been updated to Unicode 6.0.0.
+.  Two minor typos in pcre_internal.h have been fixed.
+.  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).
+.  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
+-byte code at the end of the subject (it thought there wasn't enough data
+     left).
+.  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.
+.  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().
+.  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.
+.  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.
+.  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 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.
+. More internal refactoring has drastically reduced the number of recursive
+     calls to match() for possessively repeated groups such as (abc)++ when
+     using pcre_exec().
+. 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.
+. 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.
+. 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.
+. 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).
+. 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.
+. 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.
+. 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.]
+. 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.
+. If a pattern containing (*ACCEPT) was studied, the minimum subject length
+     was incorrectly computed.
+. 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.
+. 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.
+. 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.
+. 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.
+. 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.
+. 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.
+. 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
+). A stack overflow occurred in this case. I have fixed this by limiting
+     the recursion depth to 10.
+. 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.
+. An instance of \X with an unlimited repeat could fail if at any point the
+     first character it looked at was a mark character.
+. Some minor code refactoring concerning Unicode properties and scripts
+     should reduce the stack requirement of match() slightly.
+. 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.
+. 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).
+. A *MARK encountered during the processing of a positive assertion is now
+     recorded and passed back (compatible with Perl).
+. 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.
+. 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.
+. A minor code tidy in pcre_compile() when checking options for \R usage.
+. \g was being checked for fancy things in a character class, when it should
+     just be a literal "g".
+. 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.)
+. 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).
+. Add minix to OS list not supporting the -S option in pcretest.
+. 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.
+. 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).
+. 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.
+. 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).
+. 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
+K to 20K. (The actual buffer used is three times this size.)
+     (b) The default can be changed by ./configure --with-pcregrep-bufsize when
+         PCRE is built.
+     (c) A --buffer-size=n option has been added to pcregrep, to allow the size
+         to be set at run time.
+     (d) Numerical values in pcregrep options can be followed by K or M, for
+         example --buffer-size=50K.
+     (e) If a line being scanned overflows pcregrep's buffer, an error is now
+         given and the return code is set to 2.
+. Add a pointer to the latest mark to the callout data block.
+. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
+     partial match of an empty string instead of no match. This was specific to
+     the use of ".".
+. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
+     complete match instead of a partial match. This bug was dependent on both
+     the PCRE_UTF8 and PCRE_DOTALL options being set.
+. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
+     starting byte set, because \b was not being ignored.
+ Version 8.12 15-Jan-2011
+ ------------------------
+.  Fixed some typos in the markup of the man pages, and wrote a script that
+     checks for such things as part of the documentation building process.
+.  On a big-endian 64-bit system, pcregrep did not correctly process the
+     --match-limit and --recursion-limit options (added for 8.11). In
+     particular, this made one of the standard tests fail. (The integer value
+     went into the wrong half of a long int.)
+.  If the --colour option was given to pcregrep with -v (invert match), it
+     did strange things, either producing crazy output, or crashing. It should,
+     of course, ignore a request for colour when reporting lines that do not
+     match.
+.  Another pcregrep bug caused similar problems if --colour was specified with
+     -M (multiline) and the pattern match finished with a line ending.
+.  In pcregrep, when a pattern that ended with a literal newline sequence was
+     matched in multiline mode, the following line was shown as part of the
+     match. This seems wrong, so I have changed it.
+.  Another pcregrep bug in multiline mode, when --colour was specified, caused
+     the check for further matches in the same line (so they could be coloured)
+     to overrun the end of the current line. If another match was found, it was
+     incorrectly shown (and then shown again when found in the next line).
+.  If pcregrep was compiled under Windows, there was a reference to the
+     function pcregrep_exit() before it was defined. I am assuming this was
+     the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
+     reported by a user. I've moved the definition above the reference.
+ Version 8.11 10-Dec-2010
+ ------------------------
+.  (*THEN) was not working properly if there were untried alternatives prior
+     to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
+     backtracked to try for "b" instead of moving to the next alternative branch
+     at the same level (in this case, to look for "c"). The Perl documentation
+     is clear that when (*THEN) is backtracked onto, it goes to the "next
+     alternative in the innermost enclosing group".
+.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
+     such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
+     result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
+     (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
+     (*THEN).
+.  If \s appeared in a character class, it removed the VT character from
+     the class, even if it had been included by some previous item, for example
+     in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
+     of \s, but is part of the POSIX "space" class.)
+.  A partial match never returns an empty string (because you can always
+     match an empty string at the end of the subject); however the checking for
+     an empty string was starting at the "start of match" point. This has been
+     changed to the "earliest inspected character" point, because the returned
+     data for a partial match starts at this character. This means that, for
+     example, /(?<=abc)def/ gives a partial match for the subject "abc"
+     (previously it gave "no match").
+.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
+     of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
+     previously a full match would be given. However, setting PCRE_PARTIAL_HARD
+     has an implication that the given string is incomplete (because a partial
+     match is preferred over a full match). For this reason, these items now
+     give a partial match in this situation. [Aside: previously, the one case
+     /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
+     match rather than a full match, which was wrong by the old rules, but is
+     now correct.]
+.  There was a bug in the handling of #-introduced comments, recognized when
+     PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
+     If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
+     UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
+     scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
+     but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
+     places in pcre_compile().
+.  Related to (6) above, when pcre_compile() was skipping #-introduced
+     comments when looking ahead for named forward references to subpatterns,
+     the only newline sequence it recognized was NL. It now handles newlines
+     according to the set newline convention.
+.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
+     former, but used strtoul(), whereas pcretest avoided strtoul() but did not
+     cater for a lack of strerror(). These oversights have been fixed.
+.  Added --match-limit and --recursion-limit to pcregrep.
+. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
+. When the -o option was used, pcregrep was setting a return code of 1, even
+     when matches were found, and --line-buffered was not being honoured.
+. Added an optional parentheses number to the -o and --only-matching options
+     of pcregrep.
+. Imitating Perl's /g action for multiple matches is tricky when the pattern
+     can match an empty string. The code to do it in pcretest and pcredemo
+     needed fixing:
+     (a) When the newline convention was "crlf", pcretest got it wrong, skipping
+         only one byte after an empty string match just before CRLF (this case
+         just got forgotten; "any" and "anycrlf" were OK).
+     (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
+         mode when an empty string match preceded an ASCII character followed by
+         a non-ASCII character. (The code for advancing by one character rather
+         than one byte was nonsense.)
+     (c) The pcredemo.c sample program did not have any code at all to handle
+         the cases when CRLF is a valid newline sequence.
+. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
+     as a starting offset was within the subject string. There is now a new
+     error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
+     negative or greater than the length of the string. In order to test this,
+     pcretest is extended to allow the setting of negative starting offsets.
+. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
+     starting offset points to the beginning of a UTF-8 character was
+     unnecessarily clumsy. I tidied it up.
+. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
+     bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
+. Nobody had reported that the --include_dir option, which was added in
+     release 7.7 should have been called --include-dir (hyphen, not underscore)
+     for compatibility with GNU grep. I have changed it to --include-dir, but
+     left --include_dir as an undocumented synonym, and the same for
+     --exclude-dir, though that is not available in GNU grep, at least as of
+     release 2.5.4.
+. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
+     characters from a string of bytes) have been redefined so as not to use
+     loops, in order to improve performance in some environments. At the same
+     time, I abstracted some of the common code into auxiliary macros to save
+     repetition (this should not affect the compiled code).
+. If \c was followed by a multibyte UTF-8 character, bad things happened. A
+     compile-time error is now given if \c is not followed by an ASCII
+     character, that is, a byte less than 128. (In EBCDIC mode, the code is
+     different, and any byte value is allowed.)
+. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
+     START_OPTIMIZE option, which is now allowed at compile time - but just
+     passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
+     to pcregrep and other applications that have no direct access to PCRE
+     options. The new /Y option in pcretest sets this option when calling
+     pcre_compile().
+. Change 18 of release 8.01 broke the use of named subpatterns for recursive
+     back references. Groups containing recursive back references were forced to
+     be atomic by that change, but in the case of named groups, the amount of
+     memory required was incorrectly computed, leading to "Failed: internal
+     error: code overflow". This has been fixed.
+. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
+     pcretest.c, to avoid build problems in some Borland environments.
+ Version 8.10 25-Jun-2010
+ ------------------------
+.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
+     THEN.
+.  (*ACCEPT) was not working when inside an atomic group.
+.  Inside a character class, \B is treated as a literal by default, but
+     faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
+     causes the error). The code is unchanged, but I tidied the documentation.
+.  Inside a character class, PCRE always treated \R and \X as literals,
+     whereas Perl faults them if its -w option is set. I have changed PCRE so
+     that it faults them when PCRE_EXTRA is set.
+.  Added support for \N, which always matches any character other than
+     newline. (It is the same as "." when PCRE_DOTALL is not set.)
+.  When compiling pcregrep with newer versions of gcc which may have
+     FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
+     declared with attribute warn_unused_result" were given. Just casting the
+     result to (void) does not stop the warnings; a more elaborate fudge is
+     needed. I've used a macro to implement this.
+.  Minor change to pcretest.c to avoid a compiler warning.
+.  Added four artifical Unicode properties to help with an option to make
+     \s etc use properties (see next item). The new properties are: Xan
+     (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
+.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
+     use Unicode properties. (*UCP) at the start of a pattern can be used to set
+     this option. Modified pcretest to add /W to test this facility. Added
+     REG_UCP to make it available via the POSIX interface.
+. Added --line-buffered to pcregrep.
+. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
+     studied, and the match started with a letter with a code point greater than
+whose first byte was different to the first byte of the other case of
+     the letter, the other case of this starting letter was not recognized
+     (#976).
+. If a pattern that was studied started with a repeated Unicode property
+     test, for example, \p{Nd}+, there was the theoretical possibility of
+     setting up an incorrect bitmap of starting bytes, but fortunately it could
+     not have actually happened in practice until change 8 above was made (it
+     added property types that matched character-matching opcodes).
+. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
+     possible starting bytes for non-anchored patterns.
+. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
+     \R, and also a number of cases that involve Unicode properties, both
+     explicit and implicit when PCRE_UCP is set.
+. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
+     input, it could crash or give wrong results if characters with values
+     greater than 0xc0 were present in the subject string. (Detail: it assumed
+     UTF-8 input when processing these items.)
+. Added a lot of (int) casts to avoid compiler warnings in systems where
+     size_t is 64-bit (#991).
+. Added a check for running out of memory when PCRE is compiled with
+     --disable-stack-for-recursion (#990).
+. If the last data line in a file for pcretest does not have a newline on
+     the end, a newline was missing in the output.
+. The default pcre_chartables.c file recognizes only ASCII characters (values
+     less than 128) in its various bitmaps. However, there is a facility for
+     generating tables according to the current locale when PCRE is compiled. It
+     turns out that in some environments, 0x85 and 0xa0, which are Unicode space
+     characters, are recognized by isspace() and therefore were getting set in
+     these tables, and indeed these tables seem to approximate to ISO 8859. This
+     caused a problem in UTF-8 mode when pcre_study() was used to create a list
+     of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
+     which of course cannot start UTF-8 characters. I have changed the code so
+     that only real ASCII characters (less than 128) and the correct starting
+     bytes for UTF-8 encodings are set for characters greater than 127 when in
+     UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
+     altogether.)
+. Added the /T option to pcretest so as to be able to run tests with non-
+     standard character tables, thus making it possible to include the tests
+     used for 19 above in the standard set of tests.
+. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
+     reference to a subpattern the other side of a comment that contains an
+     opening parenthesis caused either an internal compiling error, or a
+     reference to the wrong subpattern.
+ Version 8.02 19-Mar-2010
+ ------------------------
+.  The Unicode data tables have been updated to Unicode 5.2.0.
+.  Added the option --libs-cpp to pcre-config, but only when C++ support is
+     configured.
+.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
+     original author of that file, following a query about its status.
+.  On systems that do not have stdint.h (e.g. Solaris), check for and include
+     inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
+.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
+     quantifier applied to a forward-referencing subroutine call, could compile
+     incorrect code or give the error "internal error: previously-checked
+     referenced subpattern not found".
+.  Both MS Visual Studio and Symbian OS have problems with initializing
+     variables to point to external functions. For these systems, therefore,
+     pcre_malloc etc. are now initialized to local functions that call the
+     relevant global functions.
+.  There were two entries missing in the vectors called coptable and poptable
+     in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
+     I've fixed the data, and added a kludgy way of testing at compile time that
+     the lengths are correct (equal to the number of opcodes).
+.  Following on from 7, I added a similar kludge to check the length of the
+     eint vector in pcreposix.c.
+.  Error texts for pcre_compile() are held as one long string to avoid too
+     much relocation at load time. To find a text, the string is searched,
+     counting zeros. There was no check for running off the end of the string,
+     which could happen if a new error number was added without updating the
+     string.
+. \K gave a compile-time error if it appeared in a lookbehind assersion.
+. \K was not working if it appeared in an atomic group or in a group that
+     was called as a "subroutine", or in an assertion. Perl 5.11 documents that
+     \K is "not well defined" if used in an assertion. PCRE now accepts it if
+     the assertion is positive, but not if it is negative.
+. Change 11 fortuitously reduced the size of the stack frame used in the
+     "match()" function of pcre_exec.c by one pointer. Forthcoming
+     implementation of support for (*MARK) will need an extra pointer on the
+     stack; I have reserved it now, so that the stack frame size does not
+     decrease.
+. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
+     item in branch that calls a recursion is a subroutine call - as in the
+     second branch in the above example - was incorrectly given the compile-
+     time error "recursive call could loop indefinitely" because pcre_compile()
+     was not correctly checking the subroutine for matching a non-empty string.
+. The checks for overrunning compiling workspace could trigger after an
+     overrun had occurred. This is a "should never occur" error, but it can be
+     triggered by pathological patterns such as hundreds of nested parentheses.
+     The checks now trigger 100 bytes before the end of the workspace.
+. Fix typo in configure.ac: "srtoq" should be "strtoq".
+ Version 8.01 19-Jan-2010
+ ------------------------
+.  If a pattern contained a conditional subpattern with only one branch (in
+     particular, this includes all (*DEFINE) patterns), a call to pcre_study()
+     computed the wrong minimum data length (which is of course zero for such
+     subpatterns). This could cause incorrect "no match" results.
+.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
+     the pattern is reset in the first branch, pcre_compile() failed with
+     "internal error: code overflow at offset...". This happened only when
+     the reset was to the original external option setting. (An optimization
+     abstracts leading options settings into an external setting, which was the
+     cause of this.)
+.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
+     of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
+     assertion pattern did not match (meaning that the assertion was true), it
+     was incorrectly treated as false if the SKIP had been reached during the
+     matching. This also applied to assertions used as conditions.
+.  If an item that is not supported by pcre_dfa_exec() was encountered in an
+     assertion subpattern, including such a pattern used as a condition,
+     unpredictable results occurred, instead of the error return
+     PCRE_ERROR_DFA_UITEM.
+.  The C++ GlobalReplace function was not working like Perl for the special
+     situation when an empty string is matched. It now does the fancy magic
+     stuff that is necessary.
+.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
+     removed. (These were left over from very, very early versions of PCRE.)
+.  Some cosmetic changes to the code to make life easier when compiling it
+     as part of something else:
+     (a) Change DEBUG to PCRE_DEBUG.
+     (b) In pcre_compile(), rename the member of the "branch_chain" structure
+         called "current" as "current_branch", to prevent a collision with the
+         Linux macro when compiled as a kernel module.
+     (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
+         prevent a collision with the Linux macro when compiled as a kernel
+         module.
+.  In pcre_compile() there are some checks for integer overflows that used to
+     cast potentially large values to (double). This has been changed to that
+     when building, a check for int64_t is made, and if it is found, it is used
+     instead, thus avoiding the use of floating point arithmetic. (There is no
+     other use of FP in PCRE.) If int64_t is not found, the fallback is to
+     double.
+.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
+(difference between two addresses compared to an unsigned value).
+. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
+     custom one, because of the following reported problem in Windows:
+       - libbz2 uses the Pascal calling convention (WINAPI) for the functions
+           under Win32.
+       - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
+           therefore missing the function definition.
+       - The compiler thus generates a "C" signature for the test function.
+       - The linker fails to find the "C" function.
+       - PCRE fails to configure if asked to do so against libbz2.
+. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
+     messages were output:
+       Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
+       rerunning libtoolize, to keep the correct libtool macros in-tree.
+       Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
+     I have done both of these things.
+. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
+     most of the time, it *can* run out if it is given a pattern that contains a
+     runaway infinite recursion. I updated the discussion in the pcrestack man
+     page.
+. Now that we have gone to the x.xx style of version numbers, the minor
+     version may start with zero. Using 08 or 09 is a bad idea because users
+     might check the value of PCRE_MINOR in their code, and 08 or 09 may be
+     interpreted as invalid octal numbers. I've updated the previous comment in
+     configure.ac, and also added a check that gives an error if 08 or 09 are
+     used.
+. Change 8.00/11 was not quite complete: code had been accidentally omitted,
+     causing partial matching to fail when the end of the subject matched \W
+     in a UTF-8 pattern where \W was quantified with a minimum of 3.
+. There were some discrepancies between the declarations in pcre_internal.h
+     of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
+     their definitions. The declarations used "const uschar *" and the
+     definitions used USPTR. Even though USPTR is normally defined as "const
+     unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
+     reported that: "This difference in casting confuses some C++ compilers, for
+     example, SunCC recognizes above declarations as different functions and
+     generates broken code for hbpcre." I have changed the declarations to use
+     USPTR.
+. GNU libtool is named differently on some systems. The autogen.sh script now
+     tries several variants such as glibtoolize (MacOSX) and libtoolize1x
+     (FreeBSD).
+. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
+     (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
+     comment: "Figure out how to create a longlong from a string: strtoll and
+     equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
+     instance, but it only takes 2 args instead of 3!"
+. A subtle bug concerned with back references has been fixed by a change of
+     specification, with a corresponding code fix. A pattern such as
+     ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
+     refers, was giving matches when it shouldn't. For example, xa=xaaa would
+     match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
+     same bug. Such groups have to be quantified to be useful, or contained
+     inside another quantified group. (If there's no repetition, the reference
+     can never match.) The problem arises because, having left the group and
+     moved on to the rest of the pattern, a later failure that backtracks into
+     the group uses the captured value from the final iteration of the group
+     rather than the correct earlier one. I have fixed this in PCRE by forcing
+     any group that contains a reference to itself to be an atomic group; that
+     is, there cannot be any backtracking into it once it has completed. This is
+     similar to recursive and subroutine calls.
+ Version 8.00 19-Oct-09
  ----------------------
 .  The table for translating pcre_compile() error codes into POSIX error codes
      was out-of-date, and there was no check on the pcre_compile() error code
      being within the table. This could lead to an OK return being given in
      error.
 .  Changed the call to open a subject file in pcregrep from fopen(pathname,
      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
      in a Windows environment.
 .  The pcregrep --count option prints the count for each file even when it is
      zero, as does GNU grep. However, pcregrep was also printing all files when
      --files-with-matches was added. Now, when both options are given, it prints
      counts only for those files that have at least one match. (GNU grep just
      prints the file name in this circumstance, but including the count seems
      more useful - otherwise, why use --count?) Also ensured that the
      combination -clh just lists non-zero counts, with no names.
 .  The long form of the pcregrep -F option was incorrectly implemented as
      --fixed_strings instead of --fixed-strings. This is an incompatible change,
      but it seems right to fix it, and I didn't think it was worth preserving
      the old behaviour.
 .  The command line items --regex=pattern and --regexp=pattern were not
      recognized by pcregrep, which required --regex pattern or --regexp pattern
      (with a space rather than an '='). The man page documented the '=' forms,
      which are compatible with GNU grep; these now work.
 .  No libpcreposix.pc file was created for pkg-config; there was just
      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
 .  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
      when UCP support is not needed, by modifying the Python script that
      generates it from Unicode data files. This should not matter if the module
      is correctly used as a library, but I received one complaint about 50K of
      unwanted data. My guess is that the person linked everything into his
      program rather than using a library. Anyway, it does no harm.
 .  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
      was a minimum greater than 1 for a wide character in a possessive
      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
      which had an unlimited repeat of a nested, fixed maximum repeat of a wide
      character. Chaos in the form of incorrect output or a compiling loop could
      result.
 .  The restrictions on what a pattern can contain when partial matching is
      requested for pcre_exec() have been removed. All patterns can now be
      partially matched by this function. In addition, if there are at least two
      slots in the offset vector, the offset of the earliest inspected character
      for the match and the offset of the end of the subject are set in them when
      PCRE_ERROR_PARTIAL is returned.
 . Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
      synonymous with PCRE_PARTIAL, for backwards compatibility, and
      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
-     and may be more useful for multi-segment matching, especially with
+     and may be more useful for multi-segment matching.
-     pcre_exec().
+. Partial matching with pcre_exec() is now more intuitive. A partial match
-. Partial matching with pcre_exec() is now more intuitive. A partial match
+     used to be given if ever the end of the subject was reached; now it is
-     used to be given if ever the end of the subject was reached; now it is
+     given only if matching could not proceed because another character was
-     given only if matching could not proceed because another character was
+     needed. This makes a difference in some odd cases such as Z(*FAIL) with the
-     needed. This makes a difference in some odd cases such as Z(*FAIL) with the
+     string "Z", which now yields "no match" instead of "partial match". In the
-     string "Z", which now yields "no match" instead of "partial match". In the
+     case of pcre_dfa_exec(), "no match" is given if every matching path for the
-     case of pcre_dfa_exec(), "no match" is given if every matching path for the
+     final character ended with (*FAIL).
-     final character ended with (*FAIL).
 . Restarting a match using pcre_dfa_exec() after a partial match did not work
      if the pattern had a "must contain" character that was already found in the
      earlier partial match, unless partial matching was again requested. For
      example, with the pattern /dog.(body)?/, the "must contain" character is
      "g". If the first part-match was for the string "dog", restarting with
      "sbody" failed. This bug has been fixed.
 . The string returned by pcre_dfa_exec() after a partial match has been
      changed so that it starts at the first inspected character rather than the
      first character of the match. This makes a difference only if the pattern
      starts with a lookbehind assertion or \b or \B (\K is not supported by
      pcre_dfa_exec()). It's an incompatible change, but it makes the two
      matching functions compatible, and I think it's the right thing to do.
 . Added a pcredemo man page, created automatically from the pcredemo.c file,
      so that the demonstration program is easily available in environments where
      PCRE has not been installed from source.
 . Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
      libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
      library.
 . Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
      It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
      is not the first non-POSIX option to be added. Clearly some people find
      these options useful.
 . If a caller to the POSIX matching function regexec() passes a non-zero
      value for nmatch with a NULL value for pmatch, the value of
      nmatch is forced to zero.
 . RunGrepTest did not have a test for the availability of the -u option of
      the diff command, as RunTest does. It now checks in the same way as
      RunTest, and also checks for the -b option.
 . If an odd number of negated classes containing just a single character
      interposed, within parentheses, between a forward reference to a named
      subpattern and the definition of the subpattern, compilation crashed with
      an internal error, complaining that it could not find the referenced
      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
      [The bug was that it was starting one character too far in when skipping
      over the character class, thus treating the ] as data rather than
      terminating the class. This meant it could skip too much.]
 . Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
      /g option in pcretest when the pattern contains \K, which makes it possible
      to have an empty string match not at the start, even when the pattern is
      anchored. Updated pcretest and pcredemo to use this option.
 . If the maximum number of capturing subpatterns in a recursion was greater
      than the maximum at the outer level, the higher number was returned, but
      with unset values at the outer level. The correct (outer level) value is
      now given.
 . If (*ACCEPT) appeared inside capturing parentheses, previous releases of
      PCRE did not set those parentheses (unlike Perl). I have now found a way to
      make it do so. The string so far is captured, making this feature
      compatible with Perl.
 . The tests have been re-organized, adding tests 11 and 12, to make it
      possible to check the Perl 5.10 features against Perl 5.10.
 . Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
      pattern matches a fixed length string. PCRE did not allow this; now it
      does. Neither allows recursion.
 . I finally figured out how to implement a request to provide the minimum
      length of subject string that was needed in order to match a given pattern.
      (It was back references and recursion that I had previously got hung up
      on.) This code has now been added to pcre_study(); it finds a lower bound
      to the length of subject needed. It is not necessarily the greatest lower
      bound, but using it to avoid searching strings that are too short does give
      some useful speed-ups. The value is available to calling programs via
      pcre_fullinfo().
 . While implementing 25, I discovered to my embarrassment that pcretest had
      not been passing the result of pcre_study() to pcre_dfa_exec(), so the
      study optimizations had never been tested with that matching function.
      Oops. What is worse, even when it was passed study data, there was a bug in
      pcre_dfa_exec() that meant it never actually used it. Double oops. There
      were also very few tests of studied patterns with pcre_dfa_exec().
 . If (?| is used to create subpatterns with duplicate numbers, they are now
      allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
      on the other side of the coin, they are no longer allowed to have different
      names, because these cannot be distinguished in PCRE, and this has caused
      confusion. (This is a difference from Perl.)
 . When duplicate subpattern names are present (necessarily with different
      numbers, as required by 27 above), and a test is made by name in a
      conditional pattern, either for a subpattern having been matched, or for
      recursion in such a pattern, all the associated numbered subpatterns are
      tested, and the overall condition is true if the condition is true for any
      one of them. This is the way Perl works, and is also more like the way
      testing by number works.
  Version 7.9 11-Apr-09
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