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-revision 91 by nigel,
Sat Feb 24 21:41:34 2007 UTC
+revision 608 by ph10,
Sun Jun 12 16:25:55 2011 UTC
 Line 1
  ChangeLog for PCRE
  ------------------
+ Version 8.13 30-Apr-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 collection of tests with study enabled,
+     and thereby test pcre_study() more easily.
+. 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.
+ 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.
+. 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
+     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
+     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
+     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
+ ---------------------
+.  When building with support for bzlib/zlib (pcregrep) and/or readline
+     (pcretest), all targets were linked against these libraries. This included
+     libpcre, libpcreposix, and libpcrecpp, even though they do not use these
+     libraries. This caused unwanted dependencies to be created. This problem
+     has been fixed, and now only pcregrep is linked with bzlib/zlib and only
+     pcretest is linked with readline.
+.  The "typedef int BOOL" in pcre_internal.h that was included inside the
+     "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
+     moved outside it again, because FALSE and TRUE are already defined in AIX,
+     but BOOL is not.
+.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
+     PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
+.  The pcregrep documentation said spaces were inserted as well as colons (or
+     hyphens) following file names and line numbers when outputting matching
+     lines. This is not true; no spaces are inserted. I have also clarified the
+     wording for the --colour (or --color) option.
+.  In pcregrep, when --colour was used with -o, the list of matching strings
+     was not coloured; this is different to GNU grep, so I have changed it to be
+     the same.
+.  When --colo(u)r was used in pcregrep, only the first matching substring in
+     each matching line was coloured. Now it goes on to look for further matches
+     of any of the test patterns, which is the same behaviour as GNU grep.
+.  A pattern that could match an empty string could cause pcregrep to loop; it
+     doesn't make sense to accept an empty string match in pcregrep, so I have
+     locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
+     seems to be how GNU grep behaves.
+.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
+     start or after a newline", because the conditional assertion was not being
+     correctly handled. The rule now is that both the assertion and what follows
+     in the first alternative must satisfy the test.
+.  If auto-callout was enabled in a pattern with a conditional group whose
+     condition was an assertion, PCRE could crash during matching, both with
+     pcre_exec() and pcre_dfa_exec().
+. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
+     used for matching.
+. Unicode property support in character classes was not working for
+     characters (bytes) greater than 127 when not in UTF-8 mode.
+. Added the -M command line option to pcretest.
+. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
+. Added the PCRE_NO_START_OPTIMIZE match-time option.
+. Added comments and documentation about mis-use of no_arg in the C++
+     wrapper.
+. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
+     from Martin Jerabek that uses macro names for all relevant character and
+     string constants.
+. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
+     SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
+     SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
+     these, but not everybody uses configure.
+. A conditional group that had only one branch was not being correctly
+     recognized as an item that could match an empty string. This meant that an
+     enclosing group might also not be so recognized, causing infinite looping
+     (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
+     with the subject "ab", where knowledge that the repeated group can match
+     nothing is needed in order to break the loop.
+. If a pattern that was compiled with callouts was matched using pcre_dfa_
+     exec(), but without supplying a callout function, matching went wrong.
+. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
+     leak if the size of the offset vector was greater than 30. When the vector
+     is smaller, the saved offsets during recursion go onto a local stack
+     vector, but for larger vectors malloc() is used. It was failing to free
+     when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
+     error, in fact).
+. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
+     heapframe that is used only when UTF-8 support is enabled. This caused no
+     problem, but was untidy.
+. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
+     CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
+     included within another project.
+. Steven Van Ingelgem's patches to add more options to the CMake support,
+     slightly modified by me:
+       (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
+           not building pcregrep.
+       (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
+           if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
+. Forward references, both numeric and by name, in patterns that made use of
+     duplicate group numbers, could behave incorrectly or give incorrect errors,
+     because when scanning forward to find the reference group, PCRE was not
+     taking into account the duplicate group numbers. A pattern such as
+     ^X(?3)(a)(?|(b)|(q))(Y) is an example.
+. Changed a few more instances of "const unsigned char *" to USPTR, making
+     the feature of a custom pointer more persuasive (as requested by a user).
+. Wrapped the definitions of fileno and isatty for Windows, which appear in
+     pcretest.c, inside #ifndefs, because it seems they are sometimes already
+     pre-defined.
+. Added support for (*UTF8) at the start of a pattern.
+. Arrange for flags added by the "release type" setting in CMake to be shown
+     in the configuration summary.
+ Version 7.8 05-Sep-08
+ ---------------------
+.  Replaced UCP searching code with optimized version as implemented for Ad
+     Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
+     stage table and inline lookup instead of a function, giving speed ups of 2
+     to 5 times on some simple patterns that I tested. Permission was given to
+     distribute the MultiStage2.py script that generates the tables (it's not in
+     the tarball, but is in the Subversion repository).
+.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
+     scripts.
+.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
+     a group with a zero qualifier. The result of the study could be incorrect,
+     or the function might crash, depending on the pattern.
+.  Caseless matching was not working for non-ASCII characters in back
+     references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
+     It now works when Unicode Property Support is available.
+.  In pcretest, an escape such as \x{de} in the data was always generating
+     a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
+     non-UTF-8 mode. If the value is greater than 255, it gives a warning about
+     truncation.
+.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
+.  Added two (int) casts to pcregrep when printing the difference of two
+     pointers, in case they are 64-bit values.
+.  Added comments about Mac OS X stack usage to the pcrestack man page and to
+     test 2 if it fails.
+.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
+     and a #define of that name to empty if it is not externally set. This is to
+     allow users of MSVC to set it if necessary.
+. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
+     the convenience functions in the pcre_get.c source file.
+. An option change at the start of a pattern that had top-level alternatives
+     could cause overwriting and/or a crash. This command provoked a crash in
+     some environments:
+       printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
+     This potential security problem was recorded as CVE-2008-2371.
+. For a pattern where the match had to start at the beginning or immediately
+     after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
+     pcre_dfa_exec() could read past the end of the passed subject if there was
+     no match. To help with detecting such bugs (e.g. with valgrind), I modified
+     pcretest so that it places the subject at the end of its malloc-ed buffer.
+. The change to pcretest in 12 above threw up a couple more cases when pcre_
+     exec() might read past the end of the data buffer in UTF-8 mode.
+. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
+     the data contained the byte 0x85 as part of a UTF-8 character within its
+     first line. This applied both to normal and DFA matching.
+. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
+     /^[^d]*?$/8 failed to match "abc".
+. Added a missing copyright notice to pcrecpp_internal.h.
+. Make it more clear in the documentation that values returned from
+     pcre_exec() in ovector are byte offsets, not character counts.
+. Tidied a few places to stop certain compilers from issuing warnings.
+. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
+     supplied by Stefan Weber. I made a further small update for 7.8 because
+     there is a change of source arrangements: the pcre_searchfuncs.c module is
+     replaced by pcre_ucd.c.
+ Version 7.7 07-May-08
+ ---------------------
+.  Applied Craig's patch to sort out a long long problem: "If we can't convert
+     a string to a long long, pretend we don't even have a long long." This is
+     done by checking for the strtoq, strtoll, and _strtoi64 functions.
+.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
+     pre-7.6 versions, which defined a global no_arg variable instead of putting
+     it in the RE class. (See also #8 below.)
+.  Remove a line of dead code, identified by coverity and reported by Nuno
+     Lopes.
+.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
+     (1) The include/exclude patterns were being applied to the whole pathnames
+         of files, instead of just to the final components.
+     (2) If there was more than one level of directory, the subdirectories were
+         skipped unless they satisfied the include/exclude conditions. This is
+         inconsistent with GNU grep (and could even be seen as contrary to the
+         pcregrep specification - which I improved to make it absolutely clear).
+         The action now is always to scan all levels of directory, and just
+         apply the include/exclude patterns to regular files.
+.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
+     --exclude_dir in the tests to avoid scanning .svn directories.
+.  Applied Craig's patch to the QuoteMeta function so that it escapes the
+     NUL character as backslash + 0 rather than backslash + NUL, because PCRE
+     doesn't support NULs in patterns.
+.  Added some missing "const"s to declarations of static tables in
+     pcre_compile.c and pcre_dfa_exec.c.
+.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
+     caused by fix #2  above. (Subsequently also a second patch to fix the
+     first patch. And a third patch - this was a messy problem.)
+.  Applied Craig's patch to remove the use of push_back().
+. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
+     matching function regexec().
+. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
+     which, however, unlike Perl's \g{...}, are subroutine calls, not back
+     references. PCRE supports relative numbers with this syntax (I don't think
+     Oniguruma does).
+. Previously, a group with a zero repeat such as (...){0} was completely
+     omitted from the compiled regex. However, this means that if the group
+     was called as a subroutine from elsewhere in the pattern, things went wrong
+     (an internal error was given). Such groups are now left in the compiled
+     pattern, with a new opcode that causes them to be skipped at execution
+     time.
+. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
+     to the way PCRE behaves:
+     (a) A lone ] character is dis-allowed (Perl treats it as data).
+     (b) A back reference to an unmatched subpattern matches an empty string
+         (Perl fails the current match path).
+     (c) A data ] in a character class must be notated as \] because if the
+         first data character in a class is ], it defines an empty class. (In
+         Perl it is not possible to have an empty class.) The empty class []
+         never matches; it forces failure and is equivalent to (*FAIL) or (?!).
+         The negative empty class [^] matches any one character, independently
+         of the DOTALL setting.
+. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
+     non-existent subpattern following a character class starting with ']' and
+     containing () gave an internal compiling error instead of "reference to
+     non-existent subpattern". Fortunately, when the pattern did exist, the
+     compiled code was correct. (When scanning forwards to check for the
+     existencd of the subpattern, it was treating the data ']' as terminating
+     the class, so got the count wrong. When actually compiling, the reference
+     was subsequently set up correctly.)
+. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
+     it was being rejected as not supported by pcre_dfa_exec(), even though
+     other assertions are supported. I have made pcre_dfa_exec() support
+     (*FAIL).
+. The implementation of 13c above involved the invention of a new opcode,
+     OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
+     cannot be changed at match time, I realized I could make a small
+     improvement to matching performance by compiling OP_ALLANY instead of
+     OP_ANY for "." when DOTALL was set, and then removing the runtime tests
+     on the OP_ANY path.
+. Compiling pcretest on Windows with readline support failed without the
+     following two fixes: (1) Make the unistd.h include conditional on
+     HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
+. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
+     ncurses library to be included for pcretest when ReadLine support is
+     requested, but also to allow for it to be overridden. This patch came from
+     Daniel Bergstr�m.
+. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
+     as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
+     any errors with the current Unicode tables. Thanks to Peter Kankowski for
+     spotting this.
+ Version 7.6 28-Jan-08
+ ---------------------
+.  A character class containing a very large number of characters with
+     codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
+     overflow.
+.  Patch to cut out the "long long" test in pcrecpp_unittest when
+     HAVE_LONG_LONG is not defined.
+.  Applied Christian Ehrlicher's patch to update the CMake build files to
+     bring them up to date and include new features. This patch includes:
+     - Fixed PH's badly added libz and libbz2 support.
+     - Fixed a problem with static linking.
+     - Added pcredemo. [But later removed - see 7 below.]
+     - Fixed dftables problem and added an option.
+     - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
+         HAVE_LONG_LONG.
+     - Added readline support for pcretest.
+     - Added an listing of the option settings after cmake has run.
+.  A user submitted a patch to Makefile that makes it easy to create
+     "pcre.dll" under mingw when using Configure/Make. I added stuff to
+     Makefile.am that cause it to include this special target, without
+     affecting anything else. Note that the same mingw target plus all
+     the other distribution libraries and programs are now supported
+     when configuring with CMake (see 6 below) instead of with
+     Configure/Make.
+.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
+     This is an attempt to solve the reported problem "pcrecpp::no_arg is not
+     exported in the Windows port". It has not yet been confirmed that the patch
+     solves the problem, but it does no harm.
+.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
+     NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
+     with CMake, and also correct the comment about stack recursion.
+.  Remove the automatic building of pcredemo from the ./configure system and
+     from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
+     of a program that users should build themselves after PCRE is installed, so
+     building it automatically is not really right. What is more, it gave
+     trouble in some build environments.
+.  Further tidies to CMakeLists.txt from Sheri and Christian.
+ Version 7.5 10-Jan-08
+ ---------------------
+.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
+     values in parens when parsing an RE using the C++ wrapper."
+.  Negative specials like \S did not work in character classes in UTF-8 mode.
+     Characters greater than 255 were excluded from the class instead of being
+     included.
+.  The same bug as (2) above applied to negated POSIX classes such as
+     [:^space:].
+.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
+     defined or documented. It seems to have been a typo for PCRE_STATIC, so
+     I have changed it.
+.  The construct (?&) was not diagnosed as a syntax error (it referenced the
+     first named subpattern) and a construct such as (?&a) would reference the
+     first named subpattern whose name started with "a" (in other words, the
+     length check was missing). Both these problems are fixed. "Subpattern name
+     expected" is now given for (?&) (a zero-length name), and this patch also
+     makes it give the same error for \k'' (previously it complained that that
+     was a reference to a non-existent subpattern).
+.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
+     this is right because (?- can be followed by option settings as well as by
+     digits. I have, however, made the messages clearer.
+.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
+     than the number used in the conditional) now cause a compile-time error.
+     This is actually not compatible with Perl, which accepts such patterns, but
+     treats the conditional as always being FALSE (as PCRE used to), but it
+     seems to me that giving a diagnostic is better.
+.  Change "alphameric" to the more common word "alphanumeric" in comments
+     and messages.
+.  Fix two occurrences of "backslash" in comments that should have been
+     "backspace".
+. Remove two redundant lines of code that can never be obeyed (their function
+     was moved elsewhere).
+. The program that makes PCRE's Unicode character property table had a bug
+     which caused it to generate incorrect table entries for sequences of
+     characters that have the same character type, but are in different scripts.
+     It amalgamated them into a single range, with the script of the first of
+     them. In other words, some characters were in the wrong script. There were
+     thirteen such cases, affecting characters in the following ranges:
+       U+002b0 - U+002c1
+       U+0060c - U+0060d
+       U+0061e - U+00612
+       U+0064b - U+0065e
+       U+0074d - U+0076d
+       U+01800 - U+01805
+       U+01d00 - U+01d77
+       U+01d9b - U+01dbf
+       U+0200b - U+0200f
+       U+030fc - U+030fe
+       U+03260 - U+0327f
+       U+0fb46 - U+0fbb1
+       U+10450 - U+1049d
+. The -o option (show only the matching part of a line) for pcregrep was not
+     compatible with GNU grep in that, if there was more than one match in a
+     line, it showed only the first of them. It now behaves in the same way as
+     GNU grep.
+. If the -o and -v options were combined for pcregrep, it printed a blank
+     line for every non-matching line. GNU grep prints nothing, and pcregrep now
+     does the same. The return code can be used to tell if there were any
+     non-matching lines.
+. Added --file-offsets and --line-offsets to pcregrep.
+. The pattern (?=something)(?R) was not being diagnosed as a potentially
+     infinitely looping recursion. The bug was that positive lookaheads were not
+     being skipped when checking for a possible empty match (negative lookaheads
+     and both kinds of lookbehind were skipped).
+. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
+     inclusion of <windows.h> to before rather than after the definition of
+     INVALID_FILE_ATTRIBUTES (patch from David Byron).
+. Specifying a possessive quantifier with a specific limit for a Unicode
+     character property caused pcre_compile() to compile bad code, which led at
+     runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
+     are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
+     caused the error; without that there was no problem.
+. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
+. Added --enable-pcretest-libreadline.
+. In pcrecpp.cc, the variable 'count' was incremented twice in
+     RE::GlobalReplace(). As a result, the number of replacements returned was
+     double what it should be. I removed one of the increments, but Craig sent a
+     later patch that removed the other one (the right fix) and added unit tests
+     that check the return values (which was not done before).
+. Several CMake things:
+     (1) Arranged that, when cmake is used on Unix, the libraries end up with
+         the names libpcre and libpcreposix, not just pcre and pcreposix.
+     (2) The above change means that pcretest and pcregrep are now correctly
+         linked with the newly-built libraries, not previously installed ones.
+     (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
+. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
+     crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
+     UTF-8 newline character). The key issue is that the pattern starts .*;
+     this means that the match must be either at the beginning, or after a
+     newline. The bug was in the code for advancing after a failed match and
+     checking that the new position followed a newline. It was not taking
+     account of UTF-8 characters correctly.
+. PCRE was behaving differently from Perl in the way it recognized POSIX
+     character classes. PCRE was not treating the sequence [:...:] as a
+     character class unless the ... were all letters. Perl, however, seems to
+     allow any characters between [: and :], though of course it rejects as
+     unknown any "names" that contain non-letters, because all the known class
+     names consist only of letters. Thus, Perl gives an error for [[:1234:]],
+     for example, whereas PCRE did not - it did not recognize a POSIX character
+     class. This seemed a bit dangerous, so the code has been changed to be
+     closer to Perl. The behaviour is not identical to Perl, because PCRE will
+     diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
+     treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
+     Perl does, and where it didn't before.
+. Rewrite so as to remove the single use of %n from pcregrep because in some
+     Windows environments %n is disabled by default.
+ Version 7.4 21-Sep-07
+ ---------------------
+.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
+     means that a class such as [\s] counted as "explicit reference to CR or
+     LF". That isn't really right - the whole point of the change was to try to
+     help when there was an actual mention of one of the two characters. So now
+     the change happens only if \r or \n (or a literal CR or LF) character is
+     encountered.
+.  The 32-bit options word was also used for 6 internal flags, but the numbers
+     of both had grown to the point where there were only 3 bits left.
+     Fortunately, there was spare space in the data structure, and so I have
+     moved the internal flags into a new 16-bit field to free up more option
+     bits.
+.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
+     but did not set the internal JCHANGED flag - either of these is enough to
+     control the way the "get" function works - but the PCRE_INFO_JCHANGED
+     facility is supposed to tell if (?J) was ever used, so now (?J) at the
+     start sets both bits.
+.  Added options (at build time, compile time, exec time) to change \R from
+     matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
+.  doc/pcresyntax.html was missing from the distribution.
+.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
+     compatibility, even though it is no longer used.
+.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
+     strtoull to pcrecpp.cc to select the available functions in WIN32 when the
+     windows.h file is present (where different names are used). [This was
+     reversed later after testing - see 16 below.]
+.  Changed all #include <config.h> to #include "config.h". There were also
+     some further <pcre.h> cases that I changed to "pcre.h".
+.  When pcregrep was used with the --colour option, it missed the line ending
+     sequence off the lines that it output.
+. It was pointed out to me that arrays of string pointers cause lots of
+     relocations when a shared library is dynamically loaded. A technique of
+     using a single long string with a table of offsets can drastically reduce
+     these. I have refactored PCRE in four places to do this. The result is
+     dramatic:
+       Originally:                          290
+       After changing UCP table:            187
+       After changing error message table:   43
+       After changing table of "verbs"       36
+       After changing table of Posix names   22
+     Thanks to the folks working on Gregex for glib for this insight.
+. --disable-stack-for-recursion caused compiling to fail unless -enable-
+     unicode-properties was also set.
+. Updated the tests so that they work when \R is defaulted to ANYCRLF.
+. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
+     checked only for CRLF.
+. Added casts to pcretest.c to avoid compiler warnings.
+. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
+. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
+     and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
+     entirely. This removes changes made in 7 above.
+. The CMake files have been updated, and there is now more information about
+     building with CMake in the NON-UNIX-USE document.
+ Version 7.3 28-Aug-07
+ ---------------------
+. In the rejigging of the build system that eventually resulted in 7.1, the
+     line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
+     brackets there is not right, since it causes compilers to look for an
+     installed pcre.h, not the version that is in the source that is being
+     compiled (which of course may be different). I have changed it back to:
+       #include "pcre.h"
+     I have a vague recollection that the change was concerned with compiling in
+     different directories, but in the new build system, that is taken care of
+     by the VPATH setting the Makefile.
+. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
+     when the subject happened to end in the byte 0x85 (e.g. if the last
+     character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
+     characters but of course it shouldn't be taken as a newline when it is part
+     of another character. The bug was that, for an unlimited repeat of . in
+     not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
+     characters when looking for a newline.
+. A small performance improvement in the DOTALL UTF-8 mode .* case.
+. Debugging: adjusted the names of opcodes for different kinds of parentheses
+     in debug output.
+. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
+     long printing in the pcrecpp unittest when running under MinGW.
+. ESC_K was left out of the EBCDIC table.
+. Change 7.0/38 introduced a new limit on the number of nested non-capturing
+     parentheses; I made it 1000, which seemed large enough. Unfortunately, the
+     limit also applies to "virtual nesting" when a pattern is recursive, and in
+     this case 1000 isn't so big. I have been able to remove this limit at the
+     expense of backing off one optimization in certain circumstances. Normally,
+     when pcre_exec() would call its internal match() function recursively and
+     immediately return the result unconditionally, it uses a "tail recursion"
+     feature to save stack. However, when a subpattern that can match an empty
+     string has an unlimited repetition quantifier, it no longer makes this
+     optimization. That gives it a stack frame in which to save the data for
+     checking that an empty string has been matched. Previously this was taken
+     from the 1000-entry workspace that had been reserved. So now there is no
+     explicit limit, but more stack is used.
+. Applied Daniel's patches to solve problems with the import/export magic
+     syntax that is required for Windows, and which was going wrong for the
+     pcreposix and pcrecpp parts of the library. These were overlooked when this
+     problem was solved for the main library.
+. There were some crude static tests to avoid integer overflow when computing
+     the size of patterns that contain repeated groups with explicit upper
+     limits. As the maximum quantifier is 65535, the maximum group length was
+     set at 30,000 so that the product of these two numbers did not overflow a
+-bit integer. However, it turns out that people want to use groups that
+     are longer than 30,000 bytes (though not repeat them that many times).
+     Change 7.0/17 (the refactoring of the way the pattern size is computed) has
+     made it possible to implement the integer overflow checks in a much more
+     dynamic way, which I have now done. The artificial limitation on group
+     length has been removed - we now have only the limit on the total length of
+     the compiled pattern, which depends on the LINK_SIZE setting.
+. Fixed a bug in the documentation for get/copy named substring when
+     duplicate names are permitted. If none of the named substrings are set, the
+     functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
+     empty string.
+. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
+     instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
+     because the ] is interpreted as the first data character and the
+     terminating ] is not found. PCRE has been made compatible with Perl in this
+     regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
+     cause memory overwriting.
+. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
+     string has been matched (to stop an infinite loop). It was not recognizing
+     a conditional subpattern that could match an empty string if that
+     subpattern was within another subpattern. For example, it looped when
+     trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
+     condition was not nested. This bug has been fixed.
+. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
+     past the start of the subject in the presence of bytes with the top bit
+     set, for example "\x8aBCD".
+. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
+     (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
+. Optimized (?!) to (*FAIL).
+. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
+     This restricts code points to be within the range 0 to 0x10FFFF, excluding
+     the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
+     full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
+     does: it's just the validity check that is more restrictive.
+. Inserted checks for integer overflows during escape sequence (backslash)
+     processing, and also fixed erroneous offset values for syntax errors during
+     backslash processing.
+. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
+     for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
+. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
+     caused an overrun.
+. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
+     something other than just ASCII characters) inside a group that had an
+     unlimited repeat caused a loop at compile time (while checking to see
+     whether the group could match an empty string).
+. Debugging a pattern containing \p or \P could cause a crash. For example,
+     [\P{Any}] did so. (Error in the code for printing property names.)
+. An orphan \E inside a character class could cause a crash.
+. A repeated capturing bracket such as (A)? could cause a wild memory
+     reference during compilation.
+. There are several functions in pcre_compile() that scan along a compiled
+     expression for various reasons (e.g. to see if it's fixed length for look
+     behind). There were bugs in these functions when a repeated \p or \P was
+     present in the pattern. These operators have additional parameters compared
+     with \d, etc, and these were not being taken into account when moving along
+     the compiled data. Specifically:
+     (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
+         length.
+     (b) An item such as \pL+ within a repeated group could cause crashes or
+         loops.
+     (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
+         "reference to non-existent subpattern" error.
+     (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
+. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
+     characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
+. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
+. Patterns such as [\P{Yi}A] which include \p or \P and just one other
+     character were causing crashes (broken optimization).
+. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
+     \p or \P) caused a compile-time loop.
+. More problems have arisen in unanchored patterns when CRLF is a valid line
+     break. For example, the unstudied pattern [\r\n]A does not match the string
+     "\r\nA" because change 7.0/46 below moves the current point on by two
+     characters after failing to match at the start. However, the pattern \nA
+     *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
+     the same is true. There doesn't seem any very clean way out of this, but
+     what I have chosen to do makes the common cases work: PCRE now takes note
+     of whether there can be an explicit match for \r or \n anywhere in the
+     pattern, and if so, 7.0/46 no longer applies. As part of this change,
+     there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
+     pattern has explicit CR or LF references.
+. Added (*CR) etc for changing newline setting at start of pattern.
+ Version 7.2 19-Jun-07
+ ---------------------
+. If the fr_FR locale cannot be found for test 3, try the "french" locale,
+     which is apparently normally available under Windows.
+. Re-jig the pcregrep tests with different newline settings in an attempt
+     to make them independent of the local environment's newline setting.
+. Add code to configure.ac to remove -g from the CFLAGS default settings.
+. Some of the "internals" tests were previously cut out when the link size
+     was not 2, because the output contained actual offsets. The recent new
+     "Z" feature of pcretest means that these can be cut out, making the tests
+     usable with all link sizes.
+. Implemented Stan Switzer's goto replacement for longjmp() when not using
+     stack recursion. This gives a massive performance boost under BSD, but just
+     a small improvement under Linux. However, it saves one field in the frame
+     in all cases.
+. Added more features from the forthcoming Perl 5.10:
+     (a) (?-n) (where n is a string of digits) is a relative subroutine or
+         recursion call. It refers to the nth most recently opened parentheses.
+     (b) (?+n) is also a relative subroutine call; it refers to the nth next
+         to be opened parentheses.
+     (c) Conditions that refer to capturing parentheses can be specified
+         relatively, for example, (?(-2)... or (?(+3)...
+     (d) \K resets the start of the current match so that everything before
+         is not part of it.
+     (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
+     (f) \g{name} is another synonym - part of Perl 5.10's unification of
+         reference syntax.
+     (g) (?| introduces a group in which the numbering of parentheses in each
+         alternative starts with the same number.
+     (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
+. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
+     PCRE_INFO_JCHANGED.
+. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
+     terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
+     for detecting groups that can match an empty string.
+. A pattern with a very large number of alternatives (more than several
+     hundred) was running out of internal workspace during the pre-compile
+     phase, where pcre_compile() figures out how much memory will be needed. A
+     bit of new cunning has reduced the workspace needed for groups with
+     alternatives. The 1000-alternative test pattern now uses 12 bytes of
+     workspace instead of running out of the 4096 that are available.
+. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
+. Applied patch from Google to remove an optimization that didn't quite work.
+     The report of the bug said:
+       pcrecpp::RE("a*").FullMatch("aaa") matches, while
+       pcrecpp::RE("a*?").FullMatch("aaa") does not, and
+       pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
+. If \p or \P was used in non-UTF-8 mode on a character greater than 127
+     it matched the wrong number of bytes.
+ Version 7.1 24-Apr-07
+ ---------------------
+. Applied Bob Rossi and Daniel G's patches to convert the build system to one
+     that is more "standard", making use of automake and other Autotools. There
+     is some re-arrangement of the files and adjustment of comments consequent
+     on this.
+. Part of the patch fixed a problem with the pcregrep tests. The test of -r
+     for recursive directory scanning broke on some systems because the files
+     are not scanned in any specific order and on different systems the order
+     was different. A call to "sort" has been inserted into RunGrepTest for the
+     approprate test as a short-term fix. In the longer term there may be an
+     alternative.
+. I had an email from Eric Raymond about problems translating some of PCRE's
+     man pages to HTML (despite the fact that I distribute HTML pages, some
+     people do their own conversions for various reasons). The problems
+     concerned the use of low-level troff macros .br and .in. I have therefore
+     removed all such uses from the man pages (some were redundant, some could
+     be replaced by .nf/.fi pairs). The 132html script that I use to generate
+     HTML has been updated to handle .nf/.fi and to complain if it encounters
+     .br or .in.
+. Updated comments in configure.ac that get placed in config.h.in and also
+     arranged for config.h to be included in the distribution, with the name
+     config.h.generic, for the benefit of those who have to compile without
+     Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
+. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
+     Weber: (1) pcre_internal.h was missing some function renames; (2) updated
+     makevp.bat for the current PCRE, using the additional files
+     makevp_c.txt, makevp_l.txt, and pcregexp.pas.
+. A Windows user reported a minor discrepancy with test 2, which turned out
+     to be caused by a trailing space on an input line that had got lost in his
+     copy. The trailing space was an accident, so I've just removed it.
+. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
+     that is needed.
+. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
+     as "const" (a) because they are and (b) because it helps the PHP
+     maintainers who have recently made a script to detect big data structures
+     in the php code that should be moved to the .rodata section. I remembered
+     to update Builducptable as well, so it won't revert if ucptable.h is ever
+     re-created.
+. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
+     pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
+     order to be able to cut out the UTF-8 tables in the latter when UTF-8
+     support is not required. This saves 1.5-2K of code, which is important in
+     some applications.
+     Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
+     so as not to refer to the tables, even though these functions will never be
+     called when UTF-8 support is disabled. Otherwise there are problems with a
+     shared library.
+. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
+     (a) It was defining its arguments as char * instead of void *.
+     (b) It was assuming that all moves were upwards in memory; this was true
+         a long time ago when I wrote it, but is no longer the case.
+     The emulated memove() is provided for those environments that have neither
+     memmove() nor bcopy(). I didn't think anyone used it these days, but that
+     is clearly not the case, as these two bugs were recently reported.
+. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
+     and Detrail to create the HTML documentation, the .txt form of the man
+     pages, and it removes trailing spaces from listed files. It also creates
+     pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
+     case, it wraps all the #defines with #ifndefs. This script should be run
+     before "make dist".
+. Fixed two fairly obscure bugs concerned with quantified caseless matching
+     with Unicode property support.
+     (a) For a maximizing quantifier, if the two different cases of the
+         character were of different lengths in their UTF-8 codings (there are
+         some cases like this - I found 11), and the matching function had to
+         back up over a mixture of the two cases, it incorrectly assumed they
+         were both the same length.
+     (b) When PCRE was configured to use the heap rather than the stack for
+         recursion during matching, it was not correctly preserving the data for
+         the other case of a UTF-8 character when checking ahead for a match
+         while processing a minimizing repeat. If the check also involved
+         matching a wide character, but failed, corruption could cause an
+         erroneous result when trying to check for a repeat of the original
+         character.
+. Some tidying changes to the testing mechanism:
+     (a) The RunTest script now detects the internal link size and whether there
+         is UTF-8 and UCP support by running ./pcretest -C instead of relying on
+         values substituted by "configure". (The RunGrepTest script already did
+         this for UTF-8.) The configure.ac script no longer substitutes the
+         relevant variables.
+     (b) The debugging options /B and /D in pcretest show the compiled bytecode
+         with length and offset values. This means that the output is different
+         for different internal link sizes. Test 2 is skipped for link sizes
+         other than 2 because of this, bypassing the problem. Unfortunately,
+         there was also a test in test 3 (the locale tests) that used /B and
+         failed for link sizes other than 2. Rather than cut the whole test out,
+         I have added a new /Z option to pcretest that replaces the length and
+         offset values with spaces. This is now used to make test 3 independent
+         of link size. (Test 2 will be tidied up later.)
+. If erroroffset was passed as NULL to pcre_compile, it provoked a
+     segmentation fault instead of returning the appropriate error message.
+. In multiline mode when the newline sequence was set to "any", the pattern
+     ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
+     This doesn't seem right; it now treats the CRLF combination as the line
+     ending, and so does not match in that case. It's only a pattern such as ^$
+     that would hit this one: something like ^ABC$ would have failed after \r
+     and then tried again after \r\n.
+. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
+     in an attempt to make files that differ only in their line terminators
+     compare equal. This works on Linux.
+. Under certain error circumstances pcregrep might try to free random memory
+     as it exited. This is now fixed, thanks to valgrind.
+. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
+     "abc\r\n\r\n", it found an unwanted second match after the second \r. This
+     was because its rules for how to advance for /g after matching an empty
+     string at the end of a line did not allow for this case. They now check for
+     it specially.
+. pcretest is supposed to handle patterns and data of any length, by
+     extending its buffers when necessary. It was getting this wrong when the
+     buffer for a data line had to be extended.
+. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
+     CRLF as a newline sequence.
+. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
+     out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
+     I have nevertheless tidied it up.
+. Added some casts to kill warnings from HP-UX ia64 compiler.
+. Added a man page for pcre-config.
+ Version 7.0 19-Dec-06
+ ---------------------
+. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
+     moving to gcc 4.1.1.
+. The -S option for pcretest uses setrlimit(); I had omitted to #include
+     sys/time.h, which is documented as needed for this function. It doesn't
+     seem to matter on Linux, but it showed up on some releases of OS X.
+. It seems that there are systems where bytes whose values are greater than
+match isprint() in the "C" locale. The "C" locale should be the
+     default when a C program starts up. In most systems, only ASCII printing
+     characters match isprint(). This difference caused the output from pcretest
+     to vary, making some of the tests fail. I have changed pcretest so that:
+     (a) When it is outputting text in the compiled version of a pattern, bytes
+         other than 32-126 are always shown as hex escapes.
+     (b) When it is outputting text that is a matched part of a subject string,
+         it does the same, unless a different locale has been set for the match
+         (using the /L modifier). In this case, it uses isprint() to decide.
+. Fixed a major bug that caused incorrect computation of the amount of memory
+     required for a compiled pattern when options that changed within the
+     pattern affected the logic of the preliminary scan that determines the
+     length. The relevant options are -x, and -i in UTF-8 mode. The result was
+     that the computed length was too small. The symptoms of this bug were
+     either the PCRE error "internal error: code overflow" from pcre_compile(),
+     or a glibc crash with a message such as "pcretest: free(): invalid next
+     size (fast)". Examples of patterns that provoked this bug (shown in
+     pcretest format) are:
+       /(?-x: )/x
+       /(?x)(?-x: \s*#\s*)/
+       /((?i)[\x{c0}])/8
+       /(?i:[\x{c0}])/8
+     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
+     is now done differently.
+. Applied patches from Google to: (a) add a QuoteMeta function to the C++
+     wrapper classes; (b) implement a new function in the C++ scanner that is
+     more efficient than the old way of doing things because it avoids levels of
+     recursion in the regex matching; (c) add a paragraph to the documentation
+     for the FullMatch() function.
+. The escape sequence \n was being treated as whatever was defined as
+     "newline". Not only was this contrary to the documentation, which states
+     that \n is character 10 (hex 0A), but it also went horribly wrong when
+     "newline" was defined as CRLF. This has been fixed.
+. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
+     was being set to -1 for the "end of line" case (supposedly a value that no
+     character can have). Though this value is never used (the check for end of
+     line is "zero bytes in current character"), it caused compiler complaints.
+     I've changed it to 0xffffffff.
+. In pcre_version.c, the version string was being built by a sequence of
+     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
+     string (as it is for production releases) called a macro with an empty
+     argument. The C standard says the result of this is undefined. The gcc
+     compiler treats it as an empty string (which was what was wanted) but it is
+     reported that Visual C gives an error. The source has been hacked around to
+     avoid this problem.
+. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
+     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
+     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
+     of them did).
+. Originally, pcretest opened its input and output without "b"; then I was
+     told that "b" was needed in some environments, so it was added for release
+.0 to both the input and output. (It makes no difference on Unix-like
+     systems.) Later I was told that it is wrong for the input on Windows. I've
+     now abstracted the modes into two macros, to make it easier to fiddle with
+     them, and removed "b" from the input mode under Windows.
+. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
+. Added -help and --help to pcretest as an official way of being reminded
+     of the options.
+. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
+     and pcrecpp.cc because they annoy compilers at high warning levels.
+. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
+. Fixed an occurrence of == in configure.ac that should have been = (shell
+     scripts are not C programs :-) and which was not noticed because it works
+     on Linux.
+. pcretest is supposed to handle any length of pattern and data line (as one
+     line or as a continued sequence of lines) by extending its input buffer if
+     necessary. This feature was broken for very long pattern lines, leading to
+     a string of junk being passed to pcre_compile() if the pattern was longer
+     than about 50K.
+. I have done a major re-factoring of the way pcre_compile() computes the
+     amount of memory needed for a compiled pattern. Previously, there was code
+     that made a preliminary scan of the pattern in order to do this. That was
+     OK when PCRE was new, but as the facilities have expanded, it has become
+     harder and harder to keep it in step with the real compile phase, and there
+     have been a number of bugs (see for example, 4 above). I have now found a
+     cunning way of running the real compile function in a "fake" mode that
+     enables it to compute how much memory it would need, while actually only
+     ever using a few hundred bytes of working memory and without too many
+     tests of the mode. This should make future maintenance and development
+     easier. A side effect of this work is that the limit of 200 on the nesting
+     depth of parentheses has been removed (though this was never a serious
+     limitation, I suspect). However, there is a downside: pcre_compile() now
+     runs more slowly than before (30% or more, depending on the pattern). I
+     hope this isn't a big issue. There is no effect on runtime performance.
+. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
+     newline (only possible for the last line of a file) and it was a
+     pattern that set a locale (followed by /Lsomething), pcretest crashed.
+. Added additional timing features to pcretest. (1) The -tm option now times
+     matching only, not compiling. (2) Both -t and -tm can be followed, as a
+     separate command line item, by a number that specifies the number of
+     repeats to use when timing. The default is 50000; this gives better
+     precision, but takes uncomfortably long for very large patterns.
+. Extended pcre_study() to be more clever in cases where a branch of a
+     subpattern has no definite first character. For example, (a*|b*)[cd] would
+     previously give no result from pcre_study(). Now it recognizes that the
+     first character must be a, b, c, or d.
+. There was an incorrect error "recursive call could loop indefinitely" if
+     a subpattern (or the entire pattern) that was being tested for matching an
+     empty string contained only one non-empty item after a nested subpattern.
+     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
+     incorrectly, because the \d was being skipped in the check.
+. The pcretest program now has a new pattern option /B and a command line
+     option -b, which is equivalent to adding /B to every pattern. This causes
+     it to show the compiled bytecode, without the additional information that
+     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
+     is the same as /B/I).
+. A new optimization is now able automatically to treat some sequences such
+     as a*b as a*+b. More specifically, if something simple (such as a character
+     or a simple class like \d) has an unlimited quantifier, and is followed by
+     something that cannot possibly match the quantified thing, the quantifier
+     is automatically "possessified".
+. A recursive reference to a subpattern whose number was greater than 39
+     went wrong under certain circumstances in UTF-8 mode. This bug could also
+     have affected the operation of pcre_study().
+. Realized that a little bit of performance could be had by replacing
+     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
+. Timing data from pcretest is now shown to 4 decimal places instead of 3.
+. Possessive quantifiers such as a++ were previously implemented by turning
+     them into atomic groups such as ($>a+). Now they have their own opcodes,
+     which improves performance. This includes the automatically created ones
+     from 23 above.
+. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
+     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
+     the first matched character to be a colon. This applied both to named and
+     numbered groups.
+. The ucpinternal.h header file was missing its idempotency #ifdef.
+. I was sent a "project" file called libpcre.a.dev which I understand makes
+     building PCRE on Windows easier, so I have included it in the distribution.
+. There is now a check in pcretest against a ridiculously large number being
+     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
+     loop, the loop is abandoned.
+. Forward references to subpatterns in conditions such as (?(2)...) where
+     subpattern 2 is defined later cause pcre_compile() to search forwards in
+     the pattern for the relevant set of parentheses. This search went wrong
+     when there were unescaped parentheses in a character class, parentheses
+     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
+. "Subroutine" calls and backreferences were previously restricted to
+     referencing subpatterns earlier in the regex. This restriction has now
+     been removed.
+. Added a number of extra features that are going to be in Perl 5.10. On the
+     whole, these are just syntactic alternatives for features that PCRE had
+     previously implemented using the Python syntax or my own invention. The
+     other formats are all retained for compatibility.
+     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
+         as (?P<name>...). The new forms, as well as being in Perl 5.10, are
+         also .NET compatible.
+     (b) A recursion or subroutine call to a named group can now be defined as
+         (?&name) as well as (?P>name).
+     (c) A backreference to a named group can now be defined as \k<name> or
+         \k'name' as well as (?P=name). The new forms, as well as being in Perl
+.10, are also .NET compatible.
+     (d) A conditional reference to a named group can now use the syntax
+         (?(<name>) or (?('name') as well as (?(name).
+     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
+         groups (named and numbered) that are never evaluated inline, but can be
+         called as "subroutines" from elsewhere. In effect, the DEFINE condition
+         is always false. There may be only one alternative in such a group.
+     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
+         as the simple (?(R). The condition is true only if the most recent
+         recursion is that of the given number or name. It does not search out
+         through the entire recursion stack.
+     (g) The escape \gN or \g{N} has been added, where N is a positive or
+         negative number, specifying an absolute or relative reference.
+. Tidied to get rid of some further signed/unsigned compiler warnings and
+     some "unreachable code" warnings.
+. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
+     things, this adds five new scripts.
+. Perl ignores orphaned \E escapes completely. PCRE now does the same.
+     There were also incompatibilities regarding the handling of \Q..\E inside
+     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
+     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
+. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
+     matches an empty string, and forcibly breaks the loop. There were bugs in
+     this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
+     against  aaaa  the result was just "a" rather than "aaaa", for example. Two
+     separate and independent bugs (that affected different cases) have been
+     fixed.
+. Refactored the code to abolish the use of different opcodes for small
+     capturing bracket numbers. This is a tidy that I avoided doing when I
+     removed the limit on the number of capturing brackets for 3.5 back in 2001.
+     The new approach is not only tidier, it makes it possible to reduce the
+     memory needed to fix the previous bug (38).
+. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
+     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
+     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
+     mode.
+. Add \R to match any Unicode newline sequence, as suggested in the Unicode
+     report.
+. Applied patch, originally from Ari Pollak, modified by Google, to allow
+     copy construction and assignment in the C++ wrapper.
+. Updated pcregrep to support "--newline=any". In the process, I fixed a
+     couple of bugs that could have given wrong results in the "--newline=crlf"
+     case.
+. Added a number of casts and did some reorganization of signed/unsigned int
+     variables following suggestions from Dair Grant. Also renamed the variable
+     "this" as "item" because it is a C++ keyword.
+. Arranged for dftables to add
+       #include "pcre_internal.h"
+     to pcre_chartables.c because without it, gcc 4.x may remove the array
+     definition from the final binary if PCRE is built into a static library and
+     dead code stripping is activated.
+. For an unanchored pattern, if a match attempt fails at the start of a
+     newline sequence, and the newline setting is CRLF or ANY, and the next two
+     characters are CRLF, advance by two characters instead of one.
  Version 6.7 04-Jul-06
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