--- code/trunk/ChangeLog	2009/09/15 18:17:54	447
+++ code/trunk/ChangeLog	2010/11/03 18:32:55	566
@@ -1,133 +1,540 @@
 ChangeLog for PCRE
 ------------------
 
-Version 8.00 ??-???-??
+Version 8.11 10-Oct-2010
+------------------------
+
+1.  (*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".
+    
+2.  (*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). 
+    
+3.  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.)  
+    
+4.  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").
+
+5.  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.] 
+    
+6.  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().
+    
+7.  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.
+    
+8.  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.
+    
+9.  Added --match-limit and --recursion-limit to pcregrep. 
+
+10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
+
+11. 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.
+    
+12. Added an optional parentheses number to the -o and --only-matching options
+    of pcregrep. 
+    
+13. 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. 
+
+
+Version 8.10 25-Jun-2010
+------------------------
+
+1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
+    THEN.
+
+2.  (*ACCEPT) was not working when inside an atomic group.
+
+3.  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.
+
+4.  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.
+
+5.  Added support for \N, which always matches any character other than
+    newline. (It is the same as "." when PCRE_DOTALL is not set.)
+
+6.  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.
+
+7.  Minor change to pcretest.c to avoid a compiler warning.
+
+8.  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).
+
+9.  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.
+
+10. Added --line-buffered to pcregrep.
+
+11. 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
+    127 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).
+
+12. 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).
+
+13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
+    possible starting bytes for non-anchored patterns.
+
+14. 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.
+
+15. 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.)
+
+16. Added a lot of (int) casts to avoid compiler warnings in systems where
+    size_t is 64-bit (#991).
+
+17. Added a check for running out of memory when PCRE is compiled with
+    --disable-stack-for-recursion (#990).
+
+18. 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.
+
+19. 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.)
+
+20. 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.
+
+21. 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
+------------------------
+
+1.  The Unicode data tables have been updated to Unicode 5.2.0.
+
+2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
+    configured.
+
+3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
+    original author of that file, following a query about its status.
+
+4.  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.
+
+5.  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".
+
+6.  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.
+
+7.  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).
+
+8.  Following on from 7, I added a similar kludge to check the length of the
+    eint vector in pcreposix.c.
+
+9.  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.
+
+10. \K gave a compile-time error if it appeared in a lookbehind assersion.
+
+11. \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.
+
+12. 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.
+
+13. 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.
+
+14. 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.
+
+15. Fix typo in configure.ac: "srtoq" should be "strtoq".
+
+
+Version 8.01 19-Jan-2010
+------------------------
+
+1.  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.
+
+2.  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.)
+
+3.  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.
+
+4.  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.
+
+5.  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.
+
+6.  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.)
+
+7.  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.
+
+8.  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.
+
+9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
+    2005 (difference between two addresses compared to an unsigned value).
+
+10. 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.
+
+11. 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.
+
+12. 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.
+
+13. 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.
+
+14. 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.
+
+15. 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.
+
+16. GNU libtool is named differently on some systems. The autogen.sh script now
+    tries several variants such as glibtoolize (MacOSX) and libtoolize1x
+    (FreeBSD).
+
+17. 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!"
+
+18. 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
 ----------------------
 
 1.  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 
+    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.
-    
-2.  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. 
-    
+
+2.  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.
+
 3.  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 
+    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.
-    
-4.  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. 
-    
-5.  The command line items --regex=pattern and --regexp=pattern were not 
+
+4.  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.
+
+5.  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, 
+    (with a space rather than an '='). The man page documented the '=' forms,
     which are compatible with GNU grep; these now work.
-    
-6.  No libpcreposix.pc file was created for pkg-config; there was just 
+
+6.  No libpcreposix.pc file was created for pkg-config; there was just
     libpcre.pc and libpcrecpp.pc. The omission has been rectified.
-    
+
 7.  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 
+    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.
-    
+
 8.  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 
+    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.
-    
+
 9.  The restrictions on what a pattern can contain when partial matching is
-    requested for pcre_exec() have been removed. All patterns can now be 
+    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. 
-    
+    PCRE_ERROR_PARTIAL is returned.
+
 10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
     synonymous with PCRE_PARTIAL, for backwards compatibility, and
     PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
-    and may be more useful for multi-segment matching, especially with
-    pcre_exec().
-    
-11. 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). 
-    
+    and may be more useful for multi-segment matching.
+
+11. 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).
+
 12. 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 
+    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.
-    
-13. 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 
+
+13. 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.
-    
+
 14. 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.  
-    
+    so that the demonstration program is easily available in environments where
+    PCRE has not been installed from source.
+
 15. 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.
-    
+
 16. 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 
+    is not the first non-POSIX option to be added. Clearly some people find
     these options useful.
-    
-17. If a caller to the POSIX matching function regexec() passes a non-zero 
+
+17. 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. 
-    
+    nmatch is forced to zero.
+
 18. 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 
+    the diff command, as RunTest does. It now checks in the same way as
     RunTest, and also checks for the -b option.
-    
+
 19. 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 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.] 
-    
+    [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.]
+
 20. 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 
+    /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.  
-    
+    anchored. Updated pcretest and pcredemo to use this option.
+
 21. 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 
+    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.
-    
+
 22. 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.
-    
+
+23. 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.
+
+24. 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.
+
+25. 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().
+
+26. 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().
+
+27. 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.)
+
+28. 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
 ---------------------