NCBI C++ Toolkit Cross Reference

   ChangeLog for PCRE
   ------------------
   
   Version 7.9 11-Apr-09
   ---------------------
   
   1.  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.
  
  2.  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.
  
  3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
      PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
  
  4.  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.
  
  5.  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.
  
  6.  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.
  
  7.  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.
  
  8.  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.
  
  9.  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().
  
  10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
      used for matching.
  
  11. Unicode property support in character classes was not working for
      characters (bytes) greater than 127 when not in UTF-8 mode.
  
  12. Added the -M command line option to pcretest.
  
  14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
  
  15. Added the PCRE_NO_START_OPTIMIZE match-time option.
  
  16. Added comments and documentation about mis-use of no_arg in the C++
      wrapper.
  
  17. 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.
  
  18. 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.
  
  19. 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.
  
  20. If a pattern that was compiled with callouts was matched using pcre_dfa_
      exec(), but without supplying a callout function, matching went wrong.
  
  21. 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).
  
  22. 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.
  
  23. 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.
  
  24. 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.
 
 25. 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.
 
 26. 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).
 
 27. 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.
 
 28. Added support for (*UTF8) at the start of a pattern.
 
 29. Arrange for flags added by the "release type" setting in CMake to be shown
     in the configuration summary.
 
 
 Version 7.8 05-Sep-08
 ---------------------
 
 1.  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).
 
 2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
     scripts.
 
 3.  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.
 
 4.  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.
 
 5.  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.
 
 6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
 
 7.  Added two (int) casts to pcregrep when printing the difference of two
     pointers, in case they are 64-bit values.
 
 8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
     test 2 if it fails.
 
 9.  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.
 
 10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
     the convenience functions in the pcre_get.c source file.
 
 11. 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.
 
 12. 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.
 
 13. 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.
 
 14. 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.
 
 15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
     /^[^d]*?$/8 failed to match "abc".
 
 16. Added a missing copyright notice to pcrecpp_internal.h.
 
 17. Make it more clear in the documentation that values returned from
     pcre_exec() in ovector are byte offsets, not character counts.
 
 18. Tidied a few places to stop certain compilers from issuing warnings.
 
 19. 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
 ---------------------
 
 1.  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.
 
 2.  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.)
 
 3.  Remove a line of dead code, identified by coverity and reported by Nuno
     Lopes.
 
 4.  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.
 
 5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
     --exclude_dir in the tests to avoid scanning .svn directories.
 
 6.  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.
 
 7.  Added some missing "const"s to declarations of static tables in
     pcre_compile.c and pcre_dfa_exec.c.
 
 8.  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.)
 
 9.  Applied Craig's patch to remove the use of push_back().
 
 10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
     matching function regexec().
 
 11. 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).
 
 12. 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.
 
 13. 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.
 
 14. 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.)
 
 15. 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).
 
 16. 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.
 
 17. 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.
 
 18. 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 Bergström.
 
 19. 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
 ---------------------
 
 1.  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.
 
 2.  Patch to cut out the "long long" test in pcrecpp_unittest when
     HAVE_LONG_LONG is not defined.
 
 3.  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.
 
 4.  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.
 
 5.  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.
 
 6.  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.
 
 7.  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.
 
 8.  Further tidies to CMakeLists.txt from Sheri and Christian.
 
 
 Version 7.5 10-Jan-08
 ---------------------
 
 1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
     values in parens when parsing an RE using the C++ wrapper."
 
 2.  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.
 
 3.  The same bug as (2) above applied to negated POSIX classes such as
     [:^space:].
 
 4.  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.
 
 5.  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).
 
 6.  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.
 
 7.  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.
 
 8.  Change "alphameric" to the more common word "alphanumeric" in comments
     and messages.
 
 9.  Fix two occurrences of "backslash" in comments that should have been
     "backspace".
 
 10. Remove two redundant lines of code that can never be obeyed (their function
     was moved elsewhere).
 
 11. 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
 
 12. 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.
 
 13. 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.
 
 14. Added --file-offsets and --line-offsets to pcregrep.
 
 15. 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).
 
 16. 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).
 
 17. 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.
 
 18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
 
 19. Added --enable-pcretest-libreadline.
 
 20. 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).
 
 21. 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.
 
 22. 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.
 
 23. 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.
 
 24. 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
 ---------------------
 
 1.  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.
 
 2.  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.
 
 3.  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.
 
 4.  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.
 
 5.  doc/pcresyntax.html was missing from the distribution.
 
 6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
     compatibility, even though it is no longer used.
 
 7.  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.]
 
 8.  Changed all #include <config.h> to #include "config.h". There were also
     some further <pcre.h> cases that I changed to "pcre.h".
 
 9.  When pcregrep was used with the --colour option, it missed the line ending
     sequence off the lines that it output.
 
 10. 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.
 
 11. --disable-stack-for-recursion caused compiling to fail unless -enable-
     unicode-properties was also set.
 
 12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
 
 13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
     checked only for CRLF.
 
 14. Added casts to pcretest.c to avoid compiler warnings.
 
 15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
 
 16. 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.
 
 17. 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
 ---------------------
 
  1. 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.
 
  2. 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.
 
  3. A small performance improvement in the DOTALL UTF-8 mode .* case.
 
  4. Debugging: adjusted the names of opcodes for different kinds of parentheses
     in debug output.
 
  5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
     long printing in the pcrecpp unittest when running under MinGW.
 
  6. ESC_K was left out of the EBCDIC table.
 
  7. 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.
 
  8. 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.
 
  9. 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
     32-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.
 
 10. 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.
 
 11. 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.
 
 10. 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.
 
 12. 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".
 
 13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
     (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
 
 14. Optimized (?!) to (*FAIL).
 
 15. 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.
 
 16. Inserted checks for integer overflows during escape sequence (backslash)
     processing, and also fixed erroneous offset values for syntax errors during
     backslash processing.
 
 17. 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".
 
 18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
     caused an overrun.
 
 19. 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).
 
 20. 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.)
 
 21. An orphan \E inside a character class could cause a crash.
 
 22. A repeated capturing bracket such as (A)? could cause a wild memory
     reference during compilation.
 
 23. 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.
 
 24. 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").
 
 25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
 
 26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
     character were causing crashes (broken optimization).
 
 27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
     \p or \P) caused a compile-time loop.
 
 28. 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.
 
 29. Added (*CR) etc for changing newline setting at start of pattern.
 
 
 Version 7.2 19-Jun-07
 ---------------------
 
  1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
     which is apparently normally available under Windows.
 
  2. Re-jig the pcregrep tests with different newline settings in an attempt
     to make them independent of the local environment's newline setting.
 
  3. Add code to configure.ac to remove -g from the CFLAGS default settings.
 
  4. 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.
 
  5. 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.
 
  6. 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.
 
  7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
     PCRE_INFO_JCHANGED.
 
  8. 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.
 
  9. 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.
 
 10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
 
 11. 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.
 
 12. 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
 ---------------------
 
  1. 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.
 
  2. 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.
 
  3. 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.
 
  4. 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).
 
  5. 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.
 
  6. 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.
 
  7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
     that is needed.
 
  8. 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.
 
  9. 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.
 
 10. 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.
 
 11. 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".
 
 12. 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.
 
 13. 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.)
 
 14. If erroroffset was passed as NULL to pcre_compile, it provoked a
     segmentation fault instead of returning the appropriate error message.
 
 15. 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.
 
 16. 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.
 
 17. Under certain error circumstances pcregrep might try to free random memory
     as it exited. This is now fixed, thanks to valgrind.
 
 19. 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.
 
 20. 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.
 
 21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
     CRLF as a newline sequence.
 
 22. 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.
 
 23. Added some casts to kill warnings from HP-UX ia64 compiler.
 
 24. Added a man page for pcre-config.
 
 
 Version 7.0 19-Dec-06
 ---------------------
 
  1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
     moving to gcc 4.1.1.
 
  2. 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.
 
  3. It seems that there are systems where bytes whose values are greater than
     127 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.
 
  4. 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.
 
  5. 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.
 
  6. 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.
 
  7. 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.
 
  8. 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.
 
  9. 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).
 
 10. 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
     5.0 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.
 
 11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
 
 12. Added -help and --help to pcretest as an official way of being reminded
     of the options.
 
 13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
     and pcrecpp.cc because they annoy compilers at high warning levels.
 
 14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
 
 15. 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.
 
 16. 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.
 
 17. 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.
 
 18. 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.
 
 19. 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.
 
 20. 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.
 
 21. 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.
 
 22. 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).
 
 23. 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".
 
 24. 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().
 
 25. Realized that a little bit of performance could be had by replacing
     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
 
 26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
 
 27. 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.
 
 28. 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.
 
 29. The ucpinternal.h header file was missing its idempotency #ifdef.
 
 30. 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.
 
 31. 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.
 
 32. 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.
 
 33. "Subroutine" calls and backreferences were previously restricted to
     referencing subpatterns earlier in the regex. This restriction has now
     been removed.
 
 34. 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
         5.10, 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.
 
 35. Tidied to get rid of some further signed/unsigned compiler warnings and
     some "unreachable code" warnings.
 
 36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
     things, this adds five new scripts.
 
 37. 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.
 
 38. 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.
 
 39. 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).
 
 40. 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.
 
 41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
     report.
 
 42. Applied patch, originally from Ari Pollak, modified by Google, to allow
     copy construction and assignment in the C++ wrapper.
 
 43. 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.
 
 44. 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.
 
 45. 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.
 
 46. 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
 ---------------------
 
  1. In order to handle tests when input lines are enormously long, pcretest has
     been re-factored so that it automatically extends its buffers when
     necessary. The code is crude, but this _is_ just a test program. The
     default size has been increased from 32K to 50K.
 
  2. The code in pcre_study() was using the value of the re argument before
     testing it for NULL. (Of course, in any sensible call of the function, it
     won't be NULL.)
 
  3. The memmove() emulation function in pcre_internal.h, which is used on
     systems that lack both memmove() and bcopy() - that is, hardly ever -
     was missing a "static" storage class specifier.
 
  4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
     containing an extended class (one that cannot be represented by a bitmap
     because it contains high-valued characters or Unicode property items, e.g.
     [\pZ]). Almost always one would set UTF-8 mode when processing such a
     pattern, but PCRE should not loop if you do not (it no longer does).
     [Detail: two cases were found: (a) a repeated subpattern containing an
     extended class; (b) a recursive reference to a subpattern that followed a
     previous extended class. It wasn't skipping over the extended class
     correctly when UTF-8 mode was not set.]
 
  5. A negated single-character class was not being recognized as fixed-length
     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
     compile error "lookbehind assertion is not fixed length".
 
  6. The RunPerlTest auxiliary script was showing an unexpected difference
     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
     write a Perl script that can interpret lines of an input file either as
     byte characters or as UTF-8, which is what "perltest" was being required to
     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
     can't do is switch easily at run time between having the "use utf8;" pragma
     or not. In the end, I fudged it by using the RunPerlTest script to insert
     "use utf8;" explicitly for the UTF-8 tests.
 
  7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
     the end of the subject string, contrary to the documentation and to what
     Perl does. This was true of both matching functions. Now it matches only at
     the start of the subject and immediately after *internal* newlines.
 
  8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
     a pointer to an int instead of a pointer to an unsigned long int. This
     caused problems on 64-bit systems.
 
  9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
     instance of the 'standard' template library not being so standard".
 
 10. There was no check on the number of named subpatterns nor the maximum
     length of a subpattern name. The product of these values is used to compute
     the size of the memory block for a compiled pattern. By supplying a very
     long subpattern name and a large number of named subpatterns, the size
     computation could be caused to overflow. This is now prevented by limiting
     the length of names to 32 characters, and the number of named subpatterns
     to 10,000.
 
 11. Subpatterns that are repeated with specific counts have to be replicated in
     the compiled pattern. The size of memory for this was computed from the
     length of the subpattern and the repeat count. The latter is limited to
     65535, but there was no limit on the former, meaning that integer overflow
     could in principle occur. The compiled length of a repeated subpattern is
     now limited to 30,000 bytes in order to prevent this.
 
 12. Added the optional facility to have named substrings with the same name.
 
 13. Added the ability to use a named substring as a condition, using the
     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
     are numbers (not recommended). Forward references are permitted.
 
 14. Added forward references in named backreferences (if you see what I mean).
 
 15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
     pattern could run off the end of the subject. For example, the pattern
     "(?s)(.{1,5})"8 did this with the subject "ab".
 
 16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
     PCRE_CASELESS was set when matching characters that were quantified with ?
     or *.
 
 17. A character class other than a single negated character that had a minimum
     but no maximum quantifier - for example [ab]{6,} - was not handled
     correctly by pce_dfa_exec(). It would match only one character.
 
 18. A valid (though odd) pattern that looked like a POSIX character
     class but used an invalid character after [ (for example [[,abc,]]) caused
     pcre_compile() to give the error "Failed: internal error: code overflow" or
     in some cases to crash with a glibc free() error. This could even happen if
     the pattern terminated after [[ but there just happened to be a sequence of
     letters, a binary zero, and a closing ] in the memory that followed.
 
 19. Perl's treatment of octal escapes in the range \400 to \777 has changed
     over the years. Originally (before any Unicode support), just the bottom 8
     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
     output from "man perlunicode" includes this:
 
       The regular expression compiler produces polymorphic opcodes.  That
       is, the pattern adapts to the data and automatically switches to
       the Unicode character scheme when presented with Unicode data--or
       instead uses a traditional byte scheme when presented with byte
       data.
 
     Sadly, a wide octal escape does not cause a switch, and in a string with
     no other multibyte characters, these octal escapes are treated as before.
     Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
     Unicode string.
 
     I have not perpetrated such confusion in PCRE. Up till now, it took just
     the bottom 8 bits, as in old Perl. I have now made octal escapes with
     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
     translate to the appropriate multibyte character.
 
 29. Applied some refactoring to reduce the number of warnings from Microsoft
     and Borland compilers. This has included removing the fudge introduced
     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
     a warning about an unused variable.
 
 21. PCRE has not included VT (character 0x0b) in the set of whitespace
     characters since release 4.0, because Perl (from release 5.004) does not.
     [Or at least, is documented not to: some releases seem to be in conflict
     with the documentation.] However, when a pattern was studied with
     pcre_study() and all its branches started with \s, PCRE still included VT
     as a possible starting character. Of course, this did no harm; it just
     caused an unnecessary match attempt.
 
 22. Removed a now-redundant internal flag bit that recorded the fact that case
     dependency changed within the pattern. This was once needed for "required
     byte" processing, but is no longer used. This recovers a now-scarce options
     bit. Also moved the least significant internal flag bit to the most-
     significant bit of the word, which was not previously used (hangover from
     the days when it was an int rather than a uint) to free up another bit for
     the future.
 
 23. Added support for CRLF line endings as well as CR and LF. As well as the
     default being selectable at build time, it can now be changed at runtime
     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
     specify that it is scanning data with non-default line endings.
 
 24. Changed the definition of CXXLINK to make it agree with the definition of
     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
 
 25. Applied Ian Taylor's patches to avoid using another stack frame for tail
     recursions. This makes a big different to stack usage for some patterns.
 
 26. If a subpattern containing a named recursion or subroutine reference such
     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
     the space required for the compiled pattern went wrong and gave too small a
     value. Depending on the environment, this could lead to "Failed: internal
     error: code overflow at offset 49" or "glibc detected double free or
     corruption" errors.
 
 27. Applied patches from Google (a) to support the new newline modes and (b) to
     advance over multibyte UTF-8 characters in GlobalReplace.
 
 28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
     difference for some implementation of PCRE in some Windows version.
 
 29. Added some extra testing facilities to pcretest:
 
     \q<number>   in a data line sets the "match limit" value
     \Q<number>   in a data line sets the "match recursion limt" value
     -S <number>  sets the stack size, where <number> is in megabytes
 
     The -S option isn't available for Windows.
 
 
 Version 6.6 06-Feb-06
 ---------------------
 
  1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
     in pcreposix.h. I have copied the definition from pcre.h.
 
  2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
     because pcre.h is no longer a built file.
 
  3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
     not normally included in the compiled code.
 
 
 Version 6.5 01-Feb-06
 ---------------------
 
  1. When using the partial match feature with pcre_dfa_exec(), it was not
     anchoring the second and subsequent partial matches at the new starting
     point. This could lead to incorrect results. For example, with the pattern
     /1234/, partially matching against "123" and then "a4" gave a match.
 
  2. Changes to pcregrep:
 
     (a) All non-match returns from pcre_exec() were being treated as failures
         to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
         error message is output. Some extra information is given for the
         PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
         probably the only errors that are likely to be caused by users (by
         specifying a regex that has nested indefinite repeats, for instance).
         If there are more than 20 of these errors, pcregrep is abandoned.
 
     (b) A binary zero was treated as data while matching, but terminated the
         output line if it was written out. This has been fixed: binary zeroes
         are now no different to any other data bytes.
 
     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
         used to set a locale for matching. The --locale=xxxx long option has
         been added (no short equivalent) to specify a locale explicitly on the
         pcregrep command, overriding the environment variables.
 
     (d) When -B was used with -n, some line numbers in the output were one less
         than they should have been.
 
     (e) Added the -o (--only-matching) option.
 
     (f) If -A or -C was used with -c (count only), some lines of context were
         accidentally printed for the final match.
 
     (g) Added the -H (--with-filename) option.
 
     (h) The combination of options -rh failed to suppress file names for files
         that were found from directory arguments.
 
     (i) Added the -D (--devices) and -d (--directories) options.
 
     (j) Added the -F (--fixed-strings) option.
 
     (k) Allow "-" to be used as a file name for -f as well as for a data file.
 
     (l) Added the --colo(u)r option.
 
     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
         is not present by default.
 
  3. A nasty bug was discovered in the handling of recursive patterns, that is,
     items such as (?R) or (?1), when the recursion could match a number of
     alternatives. If it matched one of the alternatives, but subsequently,
     outside the recursion, there was a failure, the code tried to back up into
     the recursion. However, because of the way PCRE is implemented, this is not
     possible, and the result was an incorrect result from the match.
 
     In order to prevent this happening, the specification of recursion has
     been changed so that all such subpatterns are automatically treated as
     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
 
  4. I had overlooked the fact that, in some locales, there are characters for
     which isalpha() is true but neither isupper() nor islower() are true. In
     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
     and ordfeminine) are like this. This affected the treatment of \w and \W
     when they appeared in character classes, but not when they appeared outside
     a character class. The bit map for "word" characters is now created
     separately from the results of isalnum() instead of just taking it from the
     upper, lower, and digit maps. (Plus the underscore character, of course.)
 
  5. The above bug also affected the handling of POSIX character classes such as
     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
     permanent tables. Instead, the bit maps for such a class were previously
     created as the appropriate unions of the upper, lower, and digit bitmaps.
     Now they are created by subtraction from the [[:word:]] class, which has
     its own bitmap.
 
  6. The [[:blank:]] character class matches horizontal, but not vertical space.
     It is created by subtracting the vertical space characters (\x09, \x0a,
     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
     subtraction was done in the overall bitmap for a character class, meaning
     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
     be recognized. This bug has been fixed.
 
  7. Patches from the folks at Google:
 
       (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
       real life, but is still worth protecting against".
 
       (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
       regular expressions".
 
       (c) pcre_scanner.cc: avoid use of std::count() because not all systems
       have it.
 
       (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
       "configure" and the latter not, in order to fix a problem somebody had
       with compiling the Arg class on HP-UX.
 
       (e) Improve the error-handling of the C++ wrapper a little bit.
 
       (f) New tests for checking recursion limiting.
 
  8. The pcre_memmove() function, which is used only if the environment does not
     have a standard memmove() function (and is therefore rarely compiled),
     contained two bugs: (a) use of int instead of size_t, and (b) it was not
     returning a result (though PCRE never actually uses the result).
 
  9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
     returned instead of calling malloc() with an overflowing number that would
     most likely cause subsequent chaos.
 
 10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
 
 11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
     with this option is matched, the nmatch and pmatch options of regexec() are
     ignored.
 
 12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
     provided in case anyone wants to the the POSIX interface with UTF-8
     strings.
 
 13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
     C++ linking (needed for some HP-UX environments).
 
 14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
     (unused parameter) and in the pcre_printint() function (omitted "default"
     switch label when the default is to do nothing).
 
 15. Added some code to make it possible, when PCRE is compiled as a C++
     library, to replace subject pointers for pcre_exec() with a smart pointer
     class, thus making it possible to process discontinuous strings.
 
 16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
     much the same function. They were added by different people who were trying
     to make PCRE easy to compile on non-Unix systems. It has been suggested
     that PCRE_EXPORT be abolished now that there is more automatic apparatus
     for compiling on Windows systems. I have therefore replaced it with
     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
     defaults to "extern" for C or "extern C" for C++, which works fine on
     Unix-like systems. It is now possible to override the value of PCRE_DATA_
     SCOPE with something explicit in config.h. In addition:
 
     (a) pcreposix.h still had just "extern" instead of either of these macros;
         I have replaced it with PCRE_DATA_SCOPE.
 
     (b) Functions such as _pcre_xclass(), which are internal to the library,
         but external in the C sense, all had PCRE_EXPORT in their definitions.
         This is apparently wrong for the Windows case, so I have removed it.
         (It makes no difference on Unix-like systems.)
 
 17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
     of recursive calls to match(). This is different to MATCH_LIMIT because
     that limits the total number of calls to match(), not all of which increase
     the depth of recursion. Limiting the recursion depth limits the amount of
     stack (or heap if NO_RECURSE is set) that is used. The default can be set
     when PCRE is compiled, and changed at run time. A patch from Google adds
     this functionality to the C++ interface.
 
 18. Changes to the handling of Unicode character properties:
 
     (a) Updated the table to Unicode 4.1.0.
 
     (b) Recognize characters that are not in the table as "Cn" (undefined).
 
     (c) I revised the way the table is implemented to a much improved format
         which includes recognition of ranges. It now supports the ranges that
         are defined in UnicodeData.txt, and it also amalgamates other
         characters into ranges. This has reduced the number of entries in the
         table from around 16,000 to around 3,000, thus reducing its size
         considerably. I realized I did not need to use a tree structure after
         all - a binary chop search is just as efficient. Having reduced the
         number of entries, I extended their size from 6 bytes to 8 bytes to
         allow for more data.
 
     (d) Added support for Unicode script names via properties such as \p{Han}.
 
 19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
     matching that character.
 
 20. When matching a repeated Unicode property with a minimum greater than zero,
     (for example \pL{2,}), PCRE could look past the end of the subject if it
     reached it while seeking the minimum number of characters. This could
     happen only if some of the characters were more than one byte long, because
     there is a check for at least the minimum number of bytes.
 
 21. Refactored the implementation of \p and \P so as to be more general, to
     allow for more different types of property in future. This has changed the
     compiled form incompatibly. Anybody with saved compiled patterns that use
     \p or \P will have to recompile them.
 
 22. Added "Any" and "L&" to the supported property types.
 
 23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
     but give a compile time error if the value is greater than 0xff.
 
 24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
     accidentally not being installed or uninstalled.
 
 25. The pcre.h file was built from pcre.h.in, but the only changes that were
     made were to insert the current release number. This seemed silly, because
     it made things harder for people building PCRE on systems that don't run
     "configure". I have turned pcre.h into a distributed file, no longer built
     by "configure", with the version identification directly included. There is
     no longer a pcre.h.in file.
 
     However, this change necessitated a change to the pcre-config script as
     well. It is built from pcre-config.in, and one of the substitutions was the
     release number. I have updated configure.ac so that ./configure now finds
     the release number by grepping pcre.h.
 
 26. Added the ability to run the tests under valgrind.
 
 
 Version 6.4 05-Sep-05
 ---------------------
 
  1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
     "--" to be printed when multiple files were scanned, even when none of the
     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
     consider it to be a bug, and have restored the previous behaviour.
 
  2. A couple of code tidies to get rid of compiler warnings.
 
  3. The pcretest program used to cheat by referring to symbols in the library
     whose names begin with _pcre_. These are internal symbols that are not
     really supposed to be visible externally, and in some environments it is
     possible to suppress them. The cheating is now confined to including
     certain files from the library's source, which is a bit cleaner.
 
  4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
     file's purpose clearer.
 
  5. Reorganized pcre_ucp_findchar().
 
 
 Version 6.3 15-Aug-05
 ---------------------
 
  1. The file libpcre.pc.in did not have general read permission in the tarball.
 
  2. There were some problems when building without C++ support:
 
     (a) If C++ support was not built, "make install" and "make test" still
         tried to test it.
 
     (b) There were problems when the value of CXX was explicitly set. Some
         changes have been made to try to fix these, and ...
 
     (c) --disable-cpp can now be used to explicitly disable C++ support.
 
     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
         backslash in a target when C++ was disabled. This confuses some
         versions of "make", apparently. Using an intermediate variable solves
         this. (Same for CPP_LOBJ.)
 
  3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
     necessary on certain architectures.
 
  4. Added a setting of -export-symbols-regex to the link command to remove
     those symbols that are exported in the C sense, but actually are local
     within the library, and not documented. Their names all begin with
     "_pcre_". This is not a perfect job, because (a) we have to except some
     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
     available (and never for static libraries). I have made a note to try to
     find a way round (a) in the future.
 
 
 Version 6.2 01-Aug-05
 ---------------------
 
  1. There was no test for integer overflow of quantifier values. A construction
     such as {1111111111111111} would give undefined results. What is worse, if
     a minimum quantifier for a parenthesized subpattern overflowed and became
     negative, the calculation of the memory size went wrong. This could have
     led to memory overwriting.
 
  2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
 
  3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
     operating environments where this matters.
 
  4. Applied Giuseppe Maxia's patch to add additional features for controlling
     PCRE options from within the C++ wrapper.
 
  5. Named capturing subpatterns were not being correctly counted when a pattern
     was compiled. This caused two problems: (a) If there were more than 100
     such subpatterns, the calculation of the memory needed for the whole
     compiled pattern went wrong, leading to an overflow error. (b) Numerical
     back references of the form \12, where the number was greater than 9, were
     not recognized as back references, even though there were sufficient
     previous subpatterns.
 
  6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
     versions of gcc, e.g. 2.95.4.
 
 
 Version 6.1 21-Jun-05
 ---------------------
 
  1. There was one reference to the variable "posix" in pcretest.c that was not
     surrounded by "#if !defined NOPOSIX".
 
  2. Make it possible to compile pcretest without DFA support, UTF8 support, or
     the cross-check on the old pcre_info() function, for the benefit of the
     cut-down version of PCRE that is currently imported into Exim.
 
  3. A (silly) pattern starting with (?i)(?-i) caused an internal space
     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
     patterns that start (?i) but I don't think that matters. The use of (?i) is
     just an example; this all applies to the other options as well.
 
  4. Since libtool seems to echo the compile commands it is issuing, the output
     from "make" can be reduced a bit by putting "@" in front of each libtool
     compile command.
 
  5. Patch from the folks at Google for configure.in to be a bit more thorough
     in checking for a suitable C++ installation before trying to compile the
     C++ stuff. This should fix a reported problem when a compiler was present,
     but no suitable headers.
 
  6. The man pages all had just "PCRE" as their title. I have changed them to
     be the relevant file name. I have also arranged that these names are
     retained in the file doc/pcre.txt, which is a concatenation in text format
     of all the man pages except the little individual ones for each function.
 
  7. The NON-UNIX-USE file had not been updated for the different set of source
     files that come with release 6. I also added a few comments about the C++
     wrapper.
 
 
 Version 6.0 07-Jun-05
 ---------------------
 
  1. Some minor internal re-organization to help with my DFA experiments.
 
  2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
     didn't matter for the library itself when fully configured, but did matter
     when compiling without UCP support, or within Exim, where the ucp files are
     not imported.
 
  3. Refactoring of the library code to split up the various functions into
     different source modules. The addition of the new DFA matching code (see
     below) to a single monolithic source would have made it really too
     unwieldy, quite apart from causing all the code to be include in a
     statically linked application, when only some functions are used. This is
     relevant even without the DFA addition now that patterns can be compiled in
     one application and matched in another.
 
     The downside of splitting up is that there have to be some external
     functions and data tables that are used internally in different modules of
     the library but which are not part of the API. These have all had their
     names changed to start with "_pcre_" so that they are unlikely to clash
     with other external names.
 
  4. Added an alternate matching function, pcre_dfa_exec(), which matches using
     a different (DFA) algorithm. Although it is slower than the original
     function, it does have some advantages for certain types of matching
     problem.
 
  5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
     including restarting after a partial match.
 
  6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
     defined when compiling for Windows was sent to me. I have put it into the
     code, though I have no means of testing or verifying it.
 
  7. Added the pcre_refcount() auxiliary function.
 
  8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
     match before or at the first newline in the subject string. In pcretest,
     the /f option on a pattern can be used to set this.
 
  9. A repeated \w when used in UTF-8 mode with characters greater than 256
     would behave wrongly. This has been present in PCRE since release 4.0.
 
 10. A number of changes to the pcregrep command:
 
     (a) Refactored how -x works; insert ^(...)$ instead of setting
         PCRE_ANCHORED and checking the length, in preparation for adding
         something similar for -w.
 
     (b) Added the -w (match as a word) option.
 
     (c) Refactored the way lines are read and buffered so as to have more
         than one at a time available.
 
     (d) Implemented a pcregrep test script.
 
     (e) Added the -M (multiline match) option. This allows patterns to match
         over several lines of the subject. The buffering ensures that at least
         8K, or the rest of the document (whichever is the shorter) is available
         for matching (and similarly the previous 8K for lookbehind assertions).
 
     (f) Changed the --help output so that it now says
 
           -w, --word-regex(p)
 
         instead of two lines, one with "regex" and the other with "regexp"
         because that confused at least one person since the short forms are the
         same. (This required a bit of code, as the output is generated
         automatically from a table. It wasn't just a text change.)
 
     (g) -- can be used to terminate pcregrep options if the next thing isn't an
         option but starts with a hyphen. Could be a pattern or a path name
         starting with a hyphen, for instance.
 
     (h) "-" can be given as a file name to represent stdin.
 
     (i) When file names are being printed, "(standard input)" is used for
         the standard input, for compatibility with GNU grep. Previously
         "<stdin>" was used.
 
     (j) The option --label=xxx can be used to supply a name to be used for
         stdin when file names are being printed. There is no short form.
 
     (k) Re-factored the options decoding logic because we are going to add
         two more options that take data. Such options can now be given in four
         different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
 
     (l) Added the -A, -B, and -C options for requesting that lines of context
         around matches be printed.
 
     (m) Added the -L option to print the names of files that do not contain
         any matching lines, that is, the complement of -l.
 
     (n) The return code is 2 if any file cannot be opened, but pcregrep does
         continue to scan other files.
 
     (o) The -s option was incorrectly implemented. For compatibility with other
         greps, it now suppresses the error message for a non-existent or non-
         accessible file (but not the return code). There is a new option called
         -q that suppresses the output of matching lines, which was what -s was
         previously doing.
 
     (p) Added --include and --exclude options to specify files for inclusion
         and exclusion when recursing.
 
 11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
     Hopefully, it now does.
 
 12. Missing cast in pcre_study().
 
 13. Added an "uninstall" target to the makefile.
 
 14. Replaced "extern" in the function prototypes in Makefile.in with
     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
     world, but is set differently for Windows.
 
 15. Added a second compiling function called pcre_compile2(). The only
     difference is that it has an extra argument, which is a pointer to an
     integer error code. When there is a compile-time failure, this is set
     non-zero, in addition to the error test pointer being set to point to an
     error message. The new argument may be NULL if no error number is required
     (but then you may as well call pcre_compile(), which is now just a
     wrapper). This facility is provided because some applications need a
     numeric error indication, but it has also enabled me to tidy up the way
     compile-time errors are handled in the POSIX wrapper.
 
 16. Added VPATH=.libs to the makefile; this should help when building with one
     prefix path and installing with another. (Or so I'm told by someone who
     knows more about this stuff than I do.)
 
 17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
     match everything, including newlines. This is not POSIX-compatible, but
     somebody wanted the feature. From pcretest it can be activated by using
     both the P and the s flags.
 
 18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
 
 19. libpcre.pc was being incorrectly installed as executable.
 
 20. A couple of places in pcretest check for end-of-line by looking for '\n';
     it now also looks for '\r' so that it will work unmodified on Windows.
 
 21. Added Google's contributed C++ wrapper to the distribution.
 
 22. Added some untidy missing memory free() calls in pcretest, to keep
     Electric Fence happy when testing.
 
 
 
 Version 5.0 13-Sep-04
 ---------------------
 
  1. Internal change: literal characters are no longer packed up into items
     containing multiple characters in a single byte-string. Each character
     is now matched using a separate opcode. However, there may be more than one
     byte in the character in UTF-8 mode.
 
  2. The pcre_callout_block structure has two new fields: pattern_position and
     next_item_length. These contain the offset in the pattern to the next match
     item, and its length, respectively.
 
  3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
     insertion of callouts before each pattern item. Added the /C option to
     pcretest to make use of this.
 
  4. On the advice of a Windows user, the lines
 
       #if defined(_WIN32) || defined(WIN32)
       _setmode( _fileno( stdout ), 0x8000 );
       #endif  /* defined(_WIN32) || defined(WIN32) */
 
     have been added to the source of pcretest. This apparently does useful
     magic in relation to line terminators.
 
  5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
     for the benefit of those environments where the "b" makes a difference.
 
  6. The icc compiler has the same options as gcc, but "configure" doesn't seem
     to know about it. I have put a hack into configure.in that adds in code
     to set GCC=yes if CC=icc. This seems to end up at a point in the
     generated configure script that is early enough to affect the setting of
     compiler options, which is what is needed, but I have no means of testing
     whether it really works. (The user who reported this had patched the
     generated configure script, which of course I cannot do.)
 
     LATER: After change 22 below (new libtool files), the configure script
     seems to know about icc (and also ecc). Therefore, I have commented out
     this hack in configure.in.
 
  7. Added support for pkg-config (2 patches were sent in).
 
  8. Negated POSIX character classes that used a combination of internal tables
     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
     [[:^ascii]]. Typically, they would match almost any characters. The other
     POSIX classes were not broken in this way.
 
  9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
     to find the match, as PCRE was deluded into thinking that the match had to
     start at the start point or following a newline. The same bug applied to
     patterns with negative forward assertions or any backward assertions
     preceding ".*" at the start, unless the pattern required a fixed first
     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
 
 10. In UTF-8 mode, when moving forwards in the subject after a failed match
     starting at the last subject character, bytes beyond the end of the subject
     string were read.
 
 11. Renamed the variable "class" as "classbits" to make life easier for C++
     users. (Previously there was a macro definition, but it apparently wasn't
     enough.)
 
 12. Added the new field "tables" to the extra data so that tables can be passed
     in at exec time, or the internal tables can be re-selected. This allows
     a compiled regex to be saved and re-used at a later time by a different
     program that might have everything at different addresses.
 
 13. Modified the pcre-config script so that, when run on Solaris, it shows a
     -R library as well as a -L library.
 
 14. The debugging options of pcretest (-d on the command line or D on a
     pattern) showed incorrect output for anything following an extended class
     that contained multibyte characters and which was followed by a quantifier.
 
 15. Added optional support for general category Unicode character properties
     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
     support. It adds about 90K to the size of the library. The meanings of the
     inbuilt class escapes such as \d and \s have NOT been changed.
 
 16. Updated pcredemo.c to include calls to free() to release the memory for the
     compiled pattern.
 
 17. The generated file chartables.c was being created in the source directory
     instead of in the building directory. This caused the build to fail if the
     source directory was different from the building directory, and was
     read-only.
 
 18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
     file. No doubt somebody will tell me if they don't make sense... Also added
     Dan Mooney's comments about building on OpenVMS.
 
 19. Added support for partial matching via the PCRE_PARTIAL option for
     pcre_exec() and the \P data escape in pcretest.
 
 20. Extended pcretest with 3 new pattern features:
 
     (i)   A pattern option of the form ">rest-of-line" causes pcretest to
           write the compiled pattern to the file whose name is "rest-of-line".
           This is a straight binary dump of the data, with the saved pointer to
           the character tables forced to be NULL. The study data, if any, is
           written too. After writing, pcretest reads a new pattern.
 
     (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
           compiled pattern from the given file. There must not be any
           occurrences of "<" in the file name (pretty unlikely); if there are,
           pcretest will instead treat the initial "<" as a pattern delimiter.
           After reading in the pattern, pcretest goes on to read data lines as
           usual.
 
     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
           and 16-bit fields in a compiled pattern, to simulate a pattern that
           was compiled on a host of opposite endianness.
 
 21. The pcre-exec() function can now cope with patterns that were compiled on
     hosts of opposite endianness, with this restriction:
 
       As for any compiled expression that is saved and used later, the tables
       pointer field cannot be preserved; the extra_data field in the arguments
       to pcre_exec() should be used to pass in a tables address if a value
       other than the default internal tables were used at compile time.
 
 22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
     now diagnosed as an error. Previously, most of the time, a negative number
     would have been treated as zero, but if in addition "ovector" was passed as
     NULL, a crash could occur.
 
 23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
     new versions from the libtool 1.5 distribution (the last one is a copy of
     a file called libtool.m4). This seems to have fixed the need to patch
     "configure" to support Darwin 1.3 (which I used to do). However, I still
     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
     workstation).
 
 24. Changed the PCRE licence to be the more standard "BSD" licence.
 
 
 Version 4.5 01-Dec-03
 ---------------------
 
  1. There has been some re-arrangement of the code for the match() function so
     that it can be compiled in a version that does not call itself recursively.
     Instead, it keeps those local variables that need separate instances for
     each "recursion" in a frame on the heap, and gets/frees frames whenever it
     needs to "recurse". Keeping track of where control must go is done by means
     of setjmp/longjmp. The whole thing is implemented by a set of macros that
     hide most of the details from the main code, and operates only if
     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
     operating.
 
     To make it easier for callers to provide specially tailored get/free
     functions for this usage, two new functions, pcre_stack_malloc, and
     pcre_stack_free, are used. They are always called in strict stacking order,
     and the size of block requested is always the same.
 
     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
     PCRE has been compiled to use the stack or the heap for recursion. The
     -C option of pcretest uses this to show which version is compiled.
 
     A new data escape \S, is added to pcretest; it causes the amounts of store
     obtained and freed by both kinds of malloc/free at match time to be added
     to the output.
 
  2. Changed the locale test to use "fr_FR" instead of "fr" because that's
     what's available on my current Linux desktop machine.
 
  3. When matching a UTF-8 string, the test for a valid string at the start has
     been extended. If start_offset is not zero, PCRE now checks that it points
     to a byte that is the start of a UTF-8 character. If not, it returns
     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
     this is necessary because there may be backward assertions in the pattern.
     When matching the same subject several times, it may save resources to use
     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
 
  4. The code for checking the validity of UTF-8 strings has been tightened so
     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
     containing "overlong sequences".
 
  5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
     should have been "&", but it just so happened that all the cases this let
     through by mistake were picked up later in the function.
 
  6. I had used a variable called "isblank" - this is a C99 function, causing
     some compilers to warn. To avoid this, I renamed it (as "blankclass").
 
  7. Cosmetic: (a) only output another newline at the end of pcretest if it is
     prompting; (b) run "./pcretest /dev/null" at the start of the test script
     so the version is shown; (c) stop "make test" echoing "./RunTest".
 
  8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
 
  9. The prototype for memmove() for systems that don't have it was using
     size_t, but the inclusion of the header that defines size_t was later. I've
     moved the #includes for the C headers earlier to avoid this.
 
 10. Added some adjustments to the code to make it easier to compiler on certain
     special systems:
 
       (a) Some "const" qualifiers were missing.
       (b) Added the macro EXPORT before all exported functions; by default this
           is defined to be empty.
       (c) Changed the dftables auxiliary program (that builds chartables.c) so
           that it reads its output file name as an argument instead of writing
           to the standard output and assuming this can be redirected.
 
 11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
     class containing characters with values greater than 255, PCRE compilation
     went into a loop.
 
 12. A recursive reference to a subpattern that was within another subpattern
     that had a minimum quantifier of zero caused PCRE to crash. For example,
     (x(y(?2))z)? provoked this bug with a subject that got as far as the
     recursion. If the recursively-called subpattern itself had a zero repeat,
     that was OK.
 
 13. In pcretest, the buffer for reading a data line was set at 30K, but the
     buffer into which it was copied (for escape processing) was still set at
     1024, so long lines caused crashes.
 
 14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
     "internal error: code overflow...". This applied to any character class
     that was followed by a possessive quantifier.
 
 15. Modified the Makefile to add libpcre.la as a prerequisite for
     libpcreposix.la because I was told this is needed for a parallel build to
     work.
 
 16. If a pattern that contained .* following optional items at the start was
     studied, the wrong optimizing data was generated, leading to matching
     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
     matching string must start with a or b or c. The correct conclusion for
     this pattern is that a match can start with any character.
 
 
 Version 4.4 13-Aug-03
 ---------------------
 
  1. In UTF-8 mode, a character class containing characters with values between
     127 and 255 was not handled correctly if the compiled pattern was studied.
     In fixing this, I have also improved the studying algorithm for such
     classes (slightly).
 
  2. Three internal functions had redundant arguments passed to them. Removal
     might give a very teeny performance improvement.
 
  3. Documentation bug: the value of the capture_top field in a callout is *one
     more than* the number of the hightest numbered captured substring.
 
  4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
     in incorrectly linking with a previously installed version. They now link
     explicitly with libpcre.la.
 
  5. configure.in no longer needs to recognize Cygwin specially.
 
  6. A problem in pcre.in for Windows platforms is fixed.
 
  7. If a pattern was successfully studied, and the -d (or /D) flag was given to
     pcretest, it used to include the size of the study block as part of its
     output. Unfortunately, the structure contains a field that has a different
     size on different hardware architectures. This meant that the tests that
     showed this size failed. As the block is currently always of a fixed size,
     this information isn't actually particularly useful in pcretest output, so
     I have just removed it.
 
  8. Three pre-processor statements accidentally did not start in column 1.
     Sadly, there are *still* compilers around that complain, even though
     standard C has not required this for well over a decade. Sigh.
 
  9. In pcretest, the code for checking callouts passed small integers in the
     callout_data field, which is a void * field. However, some picky compilers
     complained about the casts involved for this on 64-bit systems. Now
     pcretest passes the address of the small integer instead, which should get
     rid of the warnings.
 
 10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
     both compile and run time, and gives an error if an invalid UTF-8 sequence
     is found. There is a option for disabling this check in cases where the
     string is known to be correct and/or the maximum performance is wanted.
 
 11. In response to a bug report, I changed one line in Makefile.in from
 
         -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
     to
         -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
 
     to look similar to other lines, but I have no way of telling whether this
     is the right thing to do, as I do not use Windows. No doubt I'll get told
     if it's wrong...
 
 
 Version 4.3 21-May-03
 ---------------------
 
 1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
    Makefile.
 
 2. Some refactoring to improve the quality of the code:
 
    (i)   The utf8_table... variables are now declared "const".
 
    (ii)  The code for \cx, which used the "case flipping" table to upper case
          lower case letters, now just substracts 32. This is ASCII-specific,
          but the whole concept of \cx is ASCII-specific, so it seems
          reasonable.
 
    (iii) PCRE was using its character types table to recognize decimal and
          hexadecimal digits in the pattern. This is silly, because it handles
          only 0-9, a-f, and A-F, but the character types table is locale-
          specific, which means strange things might happen. A private
          table is now used for this - though it costs 256 bytes, a table is
          much faster than multiple explicit tests. Of course, the standard
          character types table is still used for matching digits in subject
          strings against \d.
 
    (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
          ending in _t are). So I've renamed it as ESC_tee.
 
 3. The first argument for regexec() in the POSIX wrapper should have been
    defined as "const".
 
 4. Changed pcretest to use malloc() for its buffers so that they can be
    Electric Fenced for debugging.
 
 5. There were several places in the code where, in UTF-8 mode, PCRE would try
    to read one or more bytes before the start of the subject string. Often this
    had no effect on PCRE's behaviour, but in some circumstances it could
    provoke a segmentation fault.
 
 6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
    to try to read one or more bytes before the start of the subject string.
 
 7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
    UTF-8 support could misbehave in various ways if the subject string
    contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
    area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
    back over UTF-8 characters.)
 
 
 Version 4.2 14-Apr-03
 ---------------------
 
 1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
 
 2. Changes to the building process, supplied by Ronald Landheer-Cieslak
      [ON_WINDOWS]: new variable, "#" on non-Windows platforms
      [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
      [WIN_PREFIX]: new variable, "cyg" for Cygwin
      * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
        and BUILD_EXEEXT
      Note: automatic setting of the BUILD variables is not yet working
      set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
        compile-time but not at link-time
      [LINK]: use for linking executables only
      make different versions for Windows and non-Windows
      [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
        libraries
      [LINK_FOR_BUILD]: new variable
      [OBJEXT]: use throughout
      [EXEEXT]: use throughout
      <winshared>: new target
      <wininstall>: new target
      <dftables.o>: use native compiler
      <dftables>: use native linker
      <install>: handle Windows platform correctly
      <clean>: ditto
      <check>: ditto
      copy DLL to top builddir before testing
 
    As part of these changes, -no-undefined was removed again. This was reported
    to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
    in any case.
 
 3. Some tidies to get rid of compiler warnings:
 
    . In the match_data structure, match_limit was an unsigned long int, whereas
      match_call_count was an int. I've made them both unsigned long ints.
 
    . In pcretest the fact that a const uschar * doesn't automatically cast to
      a void * provoked a warning.
 
    . Turning on some more compiler warnings threw up some "shadow" variables
      and a few more missing casts.
 
 4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
    option, a class that contained a single character with a value between 128
    and 255 (e.g. /[\xFF]/) caused PCRE to crash.
 
 5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
    option, a class that contained several characters, but with at least one
    whose value was between 128 and 255 caused PCRE to crash.
 
 
 Version 4.1 12-Mar-03
 ---------------------
 
 1. Compiling with gcc -pedantic found a couple of places where casts were
 needed, and a string in dftables.c that was longer than standard compilers are
 required to support.
 
 2. Compiling with Sun's compiler found a few more places where the code could
 be tidied up in order to avoid warnings.
 
 3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
 first of these names is deprecated in the latest Autoconf in favour of the name
 CC_FOR_BUILD, because "host" is typically used to mean the system on which the
 compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
 analogy I have changed it to CFLAGS_FOR_BUILD.
 
 4. Added -no-undefined to the linking command in the Makefile, because this is
 apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
 linking step for the pcreposix library.
 
 5. PCRE was failing to diagnose the case of two named groups with the same
 name.
 
 6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
 literal character that is needed in the subject for a match, and scans along to
 ensure that it is present before embarking on the full matching process. This
 saves time in cases of nested unlimited repeats that are never going to match.
 Problem: the scan can take a lot of time if the subject is very long (e.g.
 megabytes), thus penalizing straightforward matches. It is now done only if the
 amount of subject to be scanned is less than 1000 bytes.
 
 7. A lesser problem with the same optimization is that it was recording the
 first character of an anchored pattern as "needed", thus provoking a search
 right along the subject, even when the first match of the pattern was going to
 fail. The "needed" character is now not set for anchored patterns, unless it
 follows something in the pattern that is of non-fixed length. Thus, it still
 fulfils its original purpose of finding quick non-matches in cases of nested
 unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
 
 
 Version 4.0 17-Feb-03
 ---------------------
 
 1. If a comment in an extended regex that started immediately after a meta-item
 extended to the end of string, PCRE compiled incorrect data. This could lead to
 all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
 
 2. Moved to autoconf 2.53 and libtool 1.4.2.
 
 3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
 the special perltest8 script is no longer needed - all the tests can be run
 from a single perltest script.
 
 4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
 by \s. It has now been removed in PCRE. This means it isn't recognized as
 whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
 class [:space:] *does* include VT, thereby creating a mess.
 
 5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
 space and tab.
 
 6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
 its new features into the main test script, reducing the number of scripts.
 
 7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
 were backward compatible, and made the (?i) apply to the whole pattern, as if
 /i were given. Now it behaves more logically, and applies the option setting
 only to what follows. PCRE has been changed to follow suit. However, if it
 finds options settings right at the start of the pattern, it extracts them into
 the global options, as before. Thus, they show up in the info data.
 
 8. Added support for the \Q...\E escape sequence. Characters in between are
 treated as literals. This is slightly different from Perl in that $ and @ are
 also handled as literals inside the quotes. In Perl, they will cause variable
 interpolation. Note the following examples:
 
     Pattern            PCRE matches      Perl matches
 
     \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
     \Qabc\$xyz\E       abc\$xyz          abc\$xyz
     \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
 
 For compatibility with Perl, \Q...\E sequences are recognized inside character
 classes as well as outside them.
 
 9. Re-organized 3 code statements in pcretest to avoid "overflow in
 floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
 (size_t) cast to one statement in pcretest and one in pcreposix to avoid
 signed/unsigned warnings.
 
 10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
 option for pcretest, so I've replaced it by a simple function that does just
 that job.
 
 11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
 "pcregrep -".
 
 12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
 Java package. This provides some syntactic sugar for simple cases of what my
 documentation calls "once-only subpatterns". A pattern such as x*+ is the same
 as (?>x*). In other words, if what is inside (?>...) is just a single repeated
 item, you can use this simplified notation. Note that only makes sense with
 greedy quantifiers. Consequently, the use of the possessive quantifier forces
 greediness, whatever the setting of the PCRE_UNGREEDY option.
 
 13. A change of greediness default within a pattern was not taking effect at
 the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
 subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
 was abstracted outside.
 
 14. PCRE now supports the \G assertion. It is true when the current matching
 position is at the start point of the match. This differs from \A when the
 starting offset is non-zero. Used with the /g option of pcretest (or similar
 code), it works in the same way as it does for Perl's /g option. If all
 alternatives of a regex begin with \G, the expression is anchored to the start
 match position, and the "anchored" flag is set in the compiled expression.
 
 15. Some bugs concerning the handling of certain option changes within patterns
 have been fixed. These applied to options other than (?ims). For example,
 "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
 been the other way round. Some of this was related to change 7 above.
 
 16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
 features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
 and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
 POSIX classes only within a class (e.g. /[[:alpha:]]/).
 
 17. Added support for Perl's \C escape. This matches one byte, even in UTF8
 mode. Unlike ".", it always matches newline, whatever the setting of
 PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
 assertions. Perl allows it, but it doesn't (in general) work because it can't
 calculate the length of the lookbehind. At least, that's the case for Perl
 5.8.0 - I've been told they are going to document that it doesn't work in
 future.
 
 18. Added an error diagnosis for escapes that PCRE does not support: these are
 \L, \l, \N, \P, \p, \U, \u, and \X.
 
 19. Although correctly diagnosing a missing ']' in a character class, PCRE was
 reading past the end of the pattern in cases such as /[abcd/.
 
 20. PCRE was getting more memory than necessary for patterns with classes that
 contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
 
 21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
 compiling PCRE for use with Virtual Pascal.
 
 22. Small fix to the Makefile to make it work properly if the build is done
 outside the source tree.
 
 23. Added a new extension: a condition to go with recursion. If a conditional
 subpattern starts with (?(R) the "true" branch is used if recursion has
 happened, whereas the "false" branch is used only at the top level.
 
 24. When there was a very long string of literal characters (over 255 bytes
 without UTF support, over 250 bytes with UTF support), the computation of how
 much memory was required could be incorrect, leading to segfaults or other
 strange effects.
 
 25. PCRE was incorrectly assuming anchoring (either to start of subject or to
 start of line for a non-DOTALL pattern) when a pattern started with (.*) and
 there was a subsequent back reference to those brackets. This meant that, for
 example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
 possible to check for precisely this case. All we can do is abandon the
 optimization if .* occurs inside capturing brackets when there are any back
 references whatsoever. (See below for a better fix that came later.)
 
 26. The handling of the optimization for finding the first character of a
 non-anchored pattern, and for finding a character that is required later in the
 match were failing in some cases. This didn't break the matching; it just
 failed to optimize when it could. The way this is done has been re-implemented.
 
 27. Fixed typo in error message for invalid (?R item (it said "(?p").
 
 28. Added a new feature that provides some of the functionality that Perl
 provides with (?{...}). The facility is termed a "callout". The way it is done
 in PCRE is for the caller to provide an optional function, by setting
 pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
 global variable. By default it is unset, which disables all calling out. To get
 the function called, the regex must include (?C) at appropriate points. This
 is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
 This provides a means of identifying different callout points. When PCRE
 reaches such a point in the regex, if pcre_callout has been set, the external
 function is called. It is provided with data in a structure called
 pcre_callout_block, which is defined in pcre.h. If the function returns 0,
 matching continues; if it returns a non-zero value, the match at the current
 point fails. However, backtracking will occur if possible. [This was changed
 later and other features added - see item 49 below.]
 
 29. pcretest is upgraded to test the callout functionality. It provides a
 callout function that displays information. By default, it shows the start of
 the match and the current position in the text. There are some new data escapes
 to vary what happens:
 
     \C+         in addition, show current contents of captured substrings
     \C-         do not supply a callout function
     \C!n        return 1 when callout number n is reached
     \C!n!m      return 1 when callout number n is reached for the mth time
 
 30. If pcregrep was called with the -l option and just a single file name, it
 output "<stdin>" if a match was found, instead of the file name.
 
 31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
 slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
 pcre_exec(). This saves a malloc/free per call. The default value of
 POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
 when configuring.
 
 32. The default maximum size of a compiled pattern is 64K. There have been a
 few cases of people hitting this limit. The code now uses macros to handle the
 storing of links as offsets within the compiled pattern. It defaults to 2-byte
 links, but this can be changed to 3 or 4 bytes by --with-link-size when
 configuring. Tests 2 and 5 work only with 2-byte links because they output
 debugging information about compiled patterns.
 
 33. Internal code re-arrangements:
 
 (a) Moved the debugging function for printing out a compiled regex into
     its own source file (printint.c) and used #include to pull it into
     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
     separate copies.
 
 (b) Defined the list of op-code names for debugging as a macro in
     internal.h so that it is next to the definition of the opcodes.
 
 (c) Defined a table of op-code lengths for simpler skipping along compiled
     code. This is again a macro in internal.h so that it is next to the
     definition of the opcodes.
 
 34. Added support for recursive calls to individual subpatterns, along the
 lines of Robin Houston's patch (but implemented somewhat differently).
 
 35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
 allow it to read and process whole directories in Win32. This code was
 contributed by Lionel Fourquaux; it has not been tested by me.
 
 36. Added support for named subpatterns. The Python syntax (?P<name>...) is
 used to name a group. Names consist of alphanumerics and underscores, and must
 be unique. Back references use the syntax (?P=name) and recursive calls use
 (?P>name) which is a PCRE extension to the Python extension. Groups still have
 numbers. The function pcre_fullinfo() can be used after compilation to extract
 a name/number map. There are three relevant calls:
 
   PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
   PCRE_INFO_NAMECOUNT            yields the number of entries
   PCRE_INFO_NAMETABLE            yields a pointer to the map.
 
 The map is a vector of fixed-size entries. The size of each entry depends on
 the length of the longest name used. The first two bytes of each entry are the
 group number, most significant byte first. There follows the corresponding
 name, zero terminated. The names are in alphabetical order.
 
 37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
 case instead of 255. Making it the same both with and without UTF-8 support
 means that the same test output works with both.
 
 38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
 calling malloc() with a zero argument.
 
 39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
 optimization. I've improved things by keeping a bitmap of backreferences with
 numbers 1-31 so that if .* occurs inside capturing brackets that are not in
 fact referenced, the optimization can be applied. It is unlikely that a
 relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
 the match to follow \n) will appear inside brackets with a number greater than
 31, but if it does, any back reference > 31 suppresses the optimization.
 
 40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
 of disabling numbered capturing parentheses. Any opening parenthesis that is
 not followed by ? behaves as if it were followed by ?: but named parentheses
 can still be used for capturing (and they will acquire numbers in the usual
 way).
 
 41. Redesigned the return codes from the match() function into yes/no/error so
 that errors can be passed back from deep inside the nested calls. A malloc
 failure while inside a recursive subpattern call now causes the
 PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
 
 42. It is now possible to set a limit on the number of times the match()
 function is called in a call to pcre_exec(). This facility makes it possible to
 limit the amount of recursion and backtracking, though not in a directly
 obvious way, because the match() function is used in a number of different
 circumstances. The count starts from zero for each position in the subject
 string (for non-anchored patterns). The default limit is, for compatibility, a
 large number, namely 10 000 000. You can change this in two ways:
 
 (a) When configuring PCRE before making, you can use --with-match-limit=n
     to set a default value for the compiled library.
 
 (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
     a different value is set. See 45 below.
 
 If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
 
 43. Added a new function pcre_config(int, void *) to enable run-time extraction
 of things that can be changed at compile time. The first argument specifies
 what is wanted and the second points to where the information is to be placed.
 The current list of available information is:
 
   PCRE_CONFIG_UTF8
 
 The output is an integer that is set to one if UTF-8 support is available;
 otherwise it is set to zero.
 
   PCRE_CONFIG_NEWLINE
 
 The output is an integer that it set to the value of the code that is used for
 newline. It is either LF (10) or CR (13).
 
   PCRE_CONFIG_LINK_SIZE
 
 The output is an integer that contains the number of bytes used for internal
 linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
 
   PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
 
 The output is an integer that contains the threshold above which the POSIX
 interface uses malloc() for output vectors. See item 31 above.
 
   PCRE_CONFIG_MATCH_LIMIT
 
 The output is an unsigned integer that contains the default limit of the number
 of match() calls in a pcre_exec() execution. See 42 above.
 
 44. pcretest has been upgraded by the addition of the -C option. This causes it
 to extract all the available output from the new pcre_config() function, and to
 output it. The program then exits immediately.
 
 45. A need has arisen to pass over additional data with calls to pcre_exec() in
 order to support additional features. One way would have been to define
 pcre_exec2() (for example) with extra arguments, but this would not have been
 extensible, and would also have required all calls to the original function to
 be mapped to the new one. Instead, I have chosen to extend the mechanism that
 is used for passing in "extra" data from pcre_study().
 
 The pcre_extra structure is now exposed and defined in pcre.h. It currently
 contains the following fields:
 
   flags         a bitmap indicating which of the following fields are set
   study_data    opaque data from pcre_study()
   match_limit   a way of specifying a limit on match() calls for a specific
                   call to pcre_exec()
   callout_data  data for callouts (see 49 below)
 
 The flag bits are also defined in pcre.h, and are
 
   PCRE_EXTRA_STUDY_DATA
   PCRE_EXTRA_MATCH_LIMIT
   PCRE_EXTRA_CALLOUT_DATA
 
 The pcre_study() function now returns one of these new pcre_extra blocks, with
 the actual study data pointed to by the study_data field, and the
 PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
 before. That is, this change is entirely upwards-compatible and requires no
 change to existing code.
 
 If you want to pass in additional data to pcre_exec(), you can either place it
 in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
 block.
 
 46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
 data string contains the escape sequence \M, pcretest calls pcre_exec() several
 times with different match limits, until it finds the minimum value needed for
 pcre_exec() to complete. The value is then output. This can be instructive; for
 most simple matches the number is quite small, but for pathological cases it
 gets very large very quickly.
 
 47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
 returns the size of the data block pointed to by the study_data field in a
 pcre_extra block, that is, the value that was passed as the argument to
 pcre_malloc() when PCRE was getting memory in which to place the information
 created by pcre_study(). The fourth argument should point to a size_t variable.
 pcretest has been extended so that this information is shown after a successful
 pcre_study() call when information about the compiled regex is being displayed.
 
 48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
 because what follows is always an absolute path. (Later: it turns out that this
 is more than cosmetic for MinGW, because it doesn't like empty path
 components.)
 
 49. Some changes have been made to the callout feature (see 28 above):
 
 (i)  A callout function now has three choices for what it returns:
 
        0  =>  success, carry on matching
      > 0  =>  failure at this point, but backtrack if possible
      < 0  =>  serious error, return this value from pcre_exec()
 
      Negative values should normally be chosen from the set of PCRE_ERROR_xxx
      values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
      "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
      use by callout functions. It will never be used by PCRE itself.
 
 (ii) The pcre_extra structure (see 45 above) has a void * field called
      callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
      pcre_callout_block structure has a field of the same name. The contents of
      the field passed in the pcre_extra structure are passed to the callout
      function in the corresponding field in the callout block. This makes it
      easier to use the same callout-containing regex from multiple threads. For
      testing, the pcretest program has a new data escape
 
        \C*n        pass the number n (may be negative) as callout_data
 
      If the callout function in pcretest receives a non-zero value as
      callout_data, it returns that value.
 
 50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
 there were some redundant $(CFLAGS) in commands that are now specified as
 $(LINK), which already includes $(CFLAGS).
 
 51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
 has been compiled with UTF-8 support *and* pcre_compile() has been compiled
 with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
 one-byte characters throughout. Note that case-insensitive matching applies
 only to characters whose values are less than 256. PCRE doesn't support the
 notion of cases for higher-valued characters.
 
 (i)   A character class whose characters are all within 0-255 is handled as
       a bit map, and the map is inverted for negative classes. Previously, a
       character > 255 always failed to match such a class; however it should
       match if the class was a negative one (e.g. [^ab]). This has been fixed.
 
 (ii)  A negated character class with a single character < 255 is coded as
       "not this character" (OP_NOT). This wasn't working properly when the test
       character was multibyte, either singly or repeated.
 
 (iii) Repeats of multibyte characters are now handled correctly in UTF-8
       mode, for example: \x{100}{2,3}.
 
 (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
       singly or repeated) now correctly test multibyte characters. However,
       PCRE doesn't recognize any characters with values greater than 255 as
       digits, spaces, or word characters. Such characters always match \D, \S,
       and \W, and never match \d, \s, or \w.
 
 (v)   Classes may now contain characters and character ranges with values
       greater than 255. For example: [ab\x{100}-\x{400}].
 
 (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
       PCRE in UTF-8 mode.
 
 52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
 PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
 retained for backwards compatibility. (Note that LASTLITERAL is also a byte
 value.)
 
 53. The single man page has become too large. I have therefore split it up into
 a number of separate man pages. These also give rise to individual HTML pages;
 these are now put in a separate directory, and there is an index.html page that
 lists them all. Some hyperlinking between the pages has been installed.
 
 54. Added convenience functions for handling named capturing parentheses.
 
 55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
 aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
 true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
 are faulted.
 
 56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
 calling configure. These values are used when compiling the dftables.c program
 which is run to generate the source of the default character tables. They
 default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
 you will need to set these values.
 
 57. Updated the building process for Windows DLL, as provided by Fred Cox.
 
 
 Version 3.9 02-Jan-02
 ---------------------
 
 1. A bit of extraneous text had somehow crept into the pcregrep documentation.
 
 2. If --disable-static was given, the building process failed when trying to
 build pcretest and pcregrep. (For some reason it was using libtool to compile
 them, which is not right, as they aren't part of the library.)
 
 
 Version 3.8 18-Dec-01
 ---------------------
 
 1. The experimental UTF-8 code was completely screwed up. It was packing the
 bytes in the wrong order. How dumb can you get?
 
 
 Version 3.7 29-Oct-01
 ---------------------
 
 1. In updating pcretest to check change 1 of version 3.6, I screwed up.
 This caused pcretest, when used on the test data, to segfault. Unfortunately,
 this didn't happen under Solaris 8, where I normally test things.
 
 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
 doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
 isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
 this fix an hour or so after the initial 3.7 release.)
 
 
 Version 3.6 23-Oct-01
 ---------------------
 
 1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
 offsets passed as NULL with zero offset count.
 
 2. The config.guess and config.sub files had not been updated when I moved to
 the latest autoconf.
 
 
 Version 3.5 15-Aug-01
 ---------------------
 
 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
 had been forgotten.
 
 2. By using declared but undefined structures, we can avoid using "void"
 definitions in pcre.h while keeping the internal definitions of the structures
 private.
 
 3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
 user point of view, this means that both static and shared libraries are built
 by default, but this can be individually controlled. More of the work of
 handling this static/shared cases is now inside libtool instead of PCRE's make
 file.
 
 4. The pcretest utility is now installed along with pcregrep because it is
 useful for users (to test regexs) and by doing this, it automatically gets
 relinked by libtool. The documentation has been turned into a man page, so
 there are now .1, .txt, and .html versions in /doc.
 
 5. Upgrades to pcregrep:
    (i)   Added long-form option names like gnu grep.
    (ii)  Added --help to list all options with an explanatory phrase.
    (iii) Added -r, --recursive to recurse into sub-directories.
    (iv)  Added -f, --file to read patterns from a file.
 
 6. pcre_exec() was referring to its "code" argument before testing that
 argument for NULL (and giving an error if it was NULL).
 
 7. Upgraded Makefile.in to allow for compiling in a different directory from
 the source directory.
 
 8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
 options bits, the pointer it was passed was to an int instead of to an unsigned
 long int. This mattered only on 64-bit systems.
 
 9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
 generated) instead of pcre.in, which it its source. Also made the same change
 in several of the .c files.
 
 10. A new release of gcc defines printf() as a macro, which broke pcretest
 because it had an ifdef in the middle of a string argument for printf(). Fixed
 by using separate calls to printf().
 
 11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
 script, to force use of CR or LF instead of \n in the source. On non-Unix
 systems, the value can be set in config.h.
 
 12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
 absolute limit. Changed the text of the error message to make this clear, and
 likewise updated the man page.
 
 13. The limit of 99 on the number of capturing subpatterns has been removed.
 The new limit is 65535, which I hope will not be a "real" limit.
 
 
 Version 3.4 22-Aug-00
 ---------------------
 
 1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
 
 2. Diagnose condition (?(0) as an error instead of crashing on matching.
 
 
 Version 3.3 01-Aug-00
 ---------------------
 
 1. If an octal character was given, but the value was greater than \377, it
 was not getting masked to the least significant bits, as documented. This could
 lead to crashes in some systems.
 
 2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
 the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
 
 3. Added the functions pcre_free_substring() and pcre_free_substring_list().
 These just pass their arguments on to (pcre_free)(), but they are provided
 because some uses of PCRE bind it to non-C systems that can call its functions,
 but cannot call free() or pcre_free() directly.
 
 4. Add "make test" as a synonym for "make check". Corrected some comments in
 the Makefile.
 
 5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
 Makefile.
 
 6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
 command called pgrep for grepping around the active processes.
 
 7. Added the beginnings of support for UTF-8 character strings.
 
 8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
 RANLIB to ./ltconfig so that they are used by libtool. I think these are all
 the relevant ones. (AR is not passed because ./ltconfig does its own figuring
 out for the ar command.)
 
 
 Version 3.2 12-May-00
 ---------------------
 
 This is purely a bug fixing release.
 
 1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
 of ZA. This was just one example of several cases that could provoke this bug,
 which was introduced by change 9 of version 2.00. The code for breaking
 infinite loops after an iteration that matches an empty string was't working
 correctly.
 
 2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
 when matched against abbab (for example). After matching an empty string, it
 wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
 caused it to match further down the string than it should.
 
 3. The code contained an inclusion of sys/types.h. It isn't clear why this
 was there because it doesn't seem to be needed, and it causes trouble on some
 systems, as it is not a Standard C header. It has been removed.
 
 4. Made 4 silly changes to the source to avoid stupid compiler warnings that
 were reported on the Macintosh. The changes were from
 
   while ((c = *(++ptr)) != 0 && c != '\n');
 to
   while ((c = *(++ptr)) != 0 && c != '\n') ;
 
 Totally extraordinary, but if that's what it takes...
 
 5. PCRE is being used in one environment where neither memmove() nor bcopy() is
 available. Added HAVE_BCOPY and an autoconf test for it; if neither
 HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
 assumes the way PCRE uses memmove() (always moving upwards).
 
 6. PCRE is being used in one environment where strchr() is not available. There
 was only one use in pcre.c, and writing it out to avoid strchr() probably gives
 faster code anyway.
 
 
 Version 3.1 09-Feb-00
 ---------------------
 
 The only change in this release is the fixing of some bugs in Makefile.in for
 the "install" target:
 
 (1) It was failing to install pcreposix.h.
 
 (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
 
 
 Version 3.0 01-Feb-00
 ---------------------
 
 1. Add support for the /+ modifier to perltest (to output $` like it does in
 pcretest).
 
 2. Add support for the /g modifier to perltest.
 
 3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
 matches null strings.
 
 4. Fix perltest so that it doesn't do unwanted things when fed an empty
 pattern. Perl treats empty patterns specially - it reuses the most recent
 pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
 effect.
 
 5. The POSIX interface was broken in that it was just handing over the POSIX
 captured string vector to pcre_exec(), but (since release 2.00) PCRE has
 required a bigger vector, with some working space on the end. This means that
 the POSIX wrapper now has to get and free some memory, and copy the results.
 
 6. Added some simple autoconf support, placing the test data and the
 documentation in separate directories, re-organizing some of the
 information files, and making it build pcre-config (a GNU standard). Also added
 libtool support for building PCRE as a shared library, which is now the
 default.
 
 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
 09 are not valid octal constants. Single digits will be used for minor values
 less than 10.
 
 8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
 existing programs that set these in the POSIX interface can use PCRE without
 modification.
 
 9. Added a new function, pcre_fullinfo() with an extensible interface. It can
 return all that pcre_info() returns, plus additional data. The pcre_info()
 function is retained for compatibility, but is considered to be obsolete.
 
 10. Added experimental recursion feature (?R) to handle one common case that
 Perl 5.6 will be able to do with (?p{...}).
 
 11. Added support for POSIX character classes like [:alpha:], which Perl is
 adopting.
 
 
 Version 2.08 31-Aug-99
 ----------------------
 
 1. When startoffset was not zero and the pattern began with ".*", PCRE was not
 trying to match at the startoffset position, but instead was moving forward to
 the next newline as if a previous match had failed.
 
 2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
 and could get into a loop if a null string was matched other than at the start
 of the subject.
 
 3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
 be distinguished at compile time, and for completeness also added PCRE_DATE.
 
 5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
 in GnuWin32 environments.
 
 
 Version 2.07 29-Jul-99
 ----------------------
 
 1. The documentation is now supplied in plain text form and HTML as well as in
 the form of man page sources.
 
 2. C++ compilers don't like assigning (void *) values to other pointer types.
 In particular this affects malloc(). Although there is no problem in Standard
 C, I've put in casts to keep C++ compilers happy.
 
 3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
 should be (const char *).
 
 4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
 be useful for non-Unix systems who don't want to bother with the POSIX stuff.
 However, I haven't made this a standard facility. The documentation doesn't
 mention it, and the Makefile doesn't support it.
 
 5. The Makefile now contains an "install" target, with editable destinations at
 the top of the file. The pcretest program is not installed.
 
 6. pgrep -V now gives the PCRE version number and date.
 
 7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
 causing the entire string to be ignored, instead of just the last character.
 
 8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
 non-matching string, it can take a very, very long time, even for strings of
 quite modest length, because of the nested recursion. PCRE now does better in
 some of these cases. It does this by remembering the last required literal
 character in the pattern, and pre-searching the subject to ensure it is present
 before running the real match. In other words, it applies a heuristic to detect
 some types of certain failure quickly, and in the above example, if presented
 with a string that has no trailing " it gives "no match" very quickly.
 
 9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
 other alternatives are tried instead.
 
 
 Version 2.06 09-Jun-99
 ----------------------
 
 1. Change pcretest's output for amount of store used to show just the code
 space, because the remainder (the data block) varies in size between 32-bit and
 64-bit systems.
 
 2. Added an extra argument to pcre_exec() to supply an offset in the subject to
 start matching at. This allows lookbehinds to work when searching for multiple
 occurrences in a string.
 
 3. Added additional options to pcretest for testing multiple occurrences:
 
    /+   outputs the rest of the string that follows a match
    /g   loops for multiple occurrences, using the new startoffset argument
    /G   loops for multiple occurrences by passing an incremented pointer
 
 4. PCRE wasn't doing the "first character" optimization for patterns starting
 with \b or \B, though it was doing it for other lookbehind assertions. That is,
 it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
 the letter 'x'. On long subject strings, this gives a significant speed-up.
 
 
 Version 2.05 21-Apr-99
 ----------------------
 
 1. Changed the type of magic_number from int to long int so that it works
 properly on 16-bit systems.
 
 2. Fixed a bug which caused patterns starting with .* not to work correctly
 when the subject string contained newline characters. PCRE was assuming
 anchoring for such patterns in all cases, which is not correct because .* will
 not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
 DOTALL is set at top level; otherwise it knows that patterns starting with .*
 must be retried after every newline in the subject.
 
 
 Version 2.04 18-Feb-99
 ----------------------
 
 1. For parenthesized subpatterns with repeats whose minimum was zero, the
 computation of the store needed to hold the pattern was incorrect (too large).
 If such patterns were nested a few deep, this could multiply and become a real
 problem.
 
 2. Added /M option to pcretest to show the memory requirement of a specific
 pattern. Made -m a synonym of -s (which does this globally) for compatibility.
 
 3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
 compiled in such a way that the backtracking after subsequent failure was
 pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
 ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
 
 
 Version 2.03 02-Feb-99
 ----------------------
 
 1. Fixed typo and small mistake in man page.
 
 2. Added 4th condition (GPL supersedes if conflict) and created separate
 LICENCE file containing the conditions.
 
 3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
 Perl, that is the internal \ allows the delimiter to be included in the
 pattern. Locked out the use of \ as a delimiter. If \ immediately follows
 the final delimiter, add \ to the end of the pattern (to test the error).
 
 4. Added the convenience functions for extracting substrings after a successful
 match. Updated pcretest to make it able to test these functions.
 
 
 Version 2.02 14-Jan-99
 ----------------------
 
 1. Initialized the working variables associated with each extraction so that
 their saving and restoring doesn't refer to uninitialized store.
 
 2. Put dummy code into study.c in order to trick the optimizer of the IBM C
 compiler for OS/2 into generating correct code. Apparently IBM isn't going to
 fix the problem.
 
 3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
 calls, and wasn't printing the correct value for compiling calls. Increased the
 default value of LOOPREPEAT, and the number of significant figures in the
 times.
 
 4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
 
 5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
 a building problem on Windows NT with a FAT file system.
 
 
 Version 2.01 21-Oct-98
 ----------------------
 
 1. Changed the API for pcre_compile() to allow for the provision of a pointer
 to character tables built by pcre_maketables() in the current locale. If NULL
 is passed, the default tables are used.
 
 
 Version 2.00 24-Sep-98
 ----------------------
 
 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
 it any more.
 
 2. Allow quantification of (?>) groups, and make it work correctly.
 
 3. The first character computation wasn't working for (?>) groups.
 
 4. Correct the implementation of \Z (it is permitted to match on the \n at the
 end of the subject) and add 5.005's \z, which really does match only at the
 very end of the subject.
 
 5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
 
 6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
 DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
 localized options. All options to pcre_study() were also removed.
 
 7. Add other new features from 5.005:
 
    $(?<=           positive lookbehind
    $(?<!           negative lookbehind
    (?imsx-imsx)    added the unsetting capability
                    such a setting is global if at outer level; local otherwise
    (?imsx-imsx:)   non-capturing groups with option setting
    (?(cond)re|re)  conditional pattern matching
 
    A backreference to itself in a repeated group matches the previous
    captured string.
 
 8. General tidying up of studying (both automatic and via "study")
 consequential on the addition of new assertions.
 
 9. As in 5.005, unlimited repeated groups that could match an empty substring
 are no longer faulted at compile time. Instead, the loop is forcibly broken at
 runtime if any iteration does actually match an empty substring.
 
 10. Include the RunTest script in the distribution.
 
 11. Added tests from the Perl 5.005_02 distribution. This showed up a few
 discrepancies, some of which were old and were also with respect to 5.004. They
 have now been fixed.
 
 
 Version 1.09 28-Apr-98
 ----------------------
 
 1. A negated single character class followed by a quantifier with a minimum
 value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
 program crashes, or just wrong answers. This did not apply to negated classes
 containing more than one character, or to minima other than one.
 
 
 Version 1.08 27-Mar-98
 ----------------------
 
 1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
 
 2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
 latter must appear before anything that relies on it in the pattern.
 
 
 Version 1.07 16-Feb-98
 ----------------------
 
 1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
 repeat of a potentially empty string).
 
 
 Version 1.06 23-Jan-98
 ----------------------
 
 1. Added Markus Oberhumer's little patches for C++.
 
 2. Literal strings longer than 255 characters were broken.
 
 
 Version 1.05 23-Dec-97
 ----------------------
 
 1. Negated character classes containing more than one character were failing if
 PCRE_CASELESS was set at run time.
 
 
 Version 1.04 19-Dec-97
 ----------------------
 
 1. Corrected the man page, where some "const" qualifiers had been omitted.
 
 2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
 input syntax.
 
 3. Fixed memory leak which occurred when a regex with back references was
 matched with an offsets vector that wasn't big enough. The temporary memory
 that is used in this case wasn't being freed if the match failed.
 
 4. Tidied pcretest to ensure it frees memory that it gets.
 
 5. Temporary memory was being obtained in the case where the passed offsets
 vector was exactly big enough.
 
 6. Corrected definition of offsetof() from change 5 below.
 
 7. I had screwed up change 6 below and broken the rules for the use of
 setjmp(). Now fixed.
 
 
 Version 1.03 18-Dec-97
 ----------------------
 
 1. A erroneous regex with a missing opening parenthesis was correctly
 diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
 on some systems.
 
 2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
 it was reported that one broken compiler failed on the former because "code" is
 also an independent variable.
 
 3. The erroneous regex a[]b caused an array overrun reference.
 
 4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
 fail on data ending with that character. (It was going on too far, and checking
 the next character, typically a binary zero.) This was specific to the
 optimized code for single-character negative classes.
 
 5. Added a contributed patch from the TIN world which does the following:
 
   + Add an undef for memmove, in case the the system defines a macro for it.
 
   + Add a definition of offsetof(), in case there isn't one. (I don't know
     the reason behind this - offsetof() is part of the ANSI standard - but
     it does no harm).
 
   + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
     most of the places where whitespace preceded '#'. I have given up and
     allowed the remaining 2 cases to be at the margin.
 
   + Rename some variables in pcre to eliminate shadowing. This seems very
     pedantic, but does no harm, of course.
 
 6. Moved the call to setjmp() into its own function, to get rid of warnings
 from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
 
 7. Constructs such as \d{8,} were compiling into the equivalent of
 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
 outcome, but in this particular case used more store than had been allocated,
 which caused the bug to be discovered because it threw up an internal error.
 
 8. The debugging code in both pcre and pcretest for outputting the compiled
 form of a regex was going wrong in the case of back references followed by
 curly-bracketed repeats.
 
 
 Version 1.02 12-Dec-97
 ----------------------
 
 1. Typos in pcre.3 and comments in the source fixed.
 
 2. Applied a contributed patch to get rid of places where it used to remove
 'const' from variables, and fixed some signed/unsigned and uninitialized
 variable warnings.
 
 3. Added the "runtest" target to Makefile.
 
 4. Set default compiler flag to -O2 rather than just -O.
 
 
 Version 1.01 19-Nov-97
 ----------------------
 
 1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
 like /([ab]*)*/, that is, for classes with more than one character in them.
 
 2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
 as /((?>a*))*/ (a PCRE_EXTRA facility).
 
 
 Version 1.00 18-Nov-97
 ----------------------
 
 1. Added compile-time macros to support systems such as SunOS4 which don't have
 memmove() or strerror() but have other things that can be used instead.
 
 2. Arranged that "make clean" removes the executables.
 
 
 Version 0.99 27-Oct-97
 ----------------------
 
 1. Fixed bug in code for optimizing classes with only one character. It was
 initializing a 32-byte map regardless, which could cause it to run off the end
 of the memory it had got.
 
 2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
 
 
 Version 0.98 22-Oct-97
 ----------------------
 
 1. Fixed bug in code for handling temporary memory usage when there are more
 back references than supplied space in the ovector. This could cause segfaults.
 
 
 Version 0.97 21-Oct-97
 ----------------------
 
 1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
 
 2. Optimized negated single characters not to use a bit map.
 
 3. Brought error texts together as macro definitions; clarified some of them;
 fixed one that was wrong - it said "range out of order" when it meant "invalid
 escape sequence".
 
 4. Changed some char * arguments to const char *.
 
 5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
 
 6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
 pcretest.
 
 
 Version 0.96 16-Oct-97
 ----------------------
 
 1. Added a simple "pgrep" utility to the distribution.
 
 2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
 unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
 where "ddd" means "one or more decimal digits".
 
 3. Fixed serious bug. If a pattern had a back reference, but the call to
 pcre_exec() didn't supply a large enough ovector to record the related
 identifying subpattern, the match always failed. PCRE now remembers the number
 of the largest back reference, and gets some temporary memory in which to save
 the offsets during matching if necessary, in order to ensure that
 backreferences always work.
 
 4. Increased the compatibility with Perl in a number of ways:
 
   (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
       to request this handling. The option can be set at compile or exec time.
 
   (b) $ matches before a terminating newline by default; an option
       PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
       mode). The option can be set at compile or exec time.
 
   (c) The handling of \ followed by a digit other than 0 is now supposed to be
       the same as Perl's. If the decimal number it represents is less than 10
       or there aren't that many previous left capturing parentheses, an octal
       escape is read. Inside a character class, it's always an octal escape,
       even if it is a single digit.
 
   (d) An escaped but undefined alphabetic character is taken as a literal,
       unless PCRE_EXTRA is set. Currently this just reserves the remaining
       escapes.
 
   (e) {0} is now permitted. (The previous item is removed from the compiled
       pattern).
 
 5. Changed all the names of code files so that the basic parts are no longer
 than 10 characters, and abolished the teeny "globals.c" file.
 
 6. Changed the handling of character classes; they are now done with a 32-byte
 bit map always.
 
 7. Added the -d and /D options to pcretest to make it possible to look at the
 internals of compilation without having to recompile pcre.
 
 
 Version 0.95 23-Sep-97
 ----------------------
 
 1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
 \x20 at the start of a run of normal characters. These were being treated as
 real characters, instead of the source characters being re-checked.
 
 
 Version 0.94 18-Sep-97
 ----------------------
 
 1. The functions are now thread-safe, with the caveat that the global variables
 containing pointers to malloc() and free() or alternative functions are the
 same for all threads.
 
 2. Get pcre_study() to generate a bitmap of initial characters for non-
 anchored patterns when this is possible, and use it if passed to pcre_exec().
 
 
 Version 0.93 15-Sep-97
 ----------------------
 
 1. /(b)|(:+)/ was computing an incorrect first character.
 
 2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
 but not actually doing anything yet.
 
 3. Treat "-" characters in classes that cannot be part of ranges as literals,
 as Perl does (e.g. [-az] or [az-]).
 
 4. Set the anchored flag if a branch starts with .* or .*? because that tests
 all possible positions.
 
 5. Split up into different modules to avoid including unneeded functions in a
 compiled binary. However, compile and exec are still in one module. The "study"
 function is split off.
 
 6. The character tables are now in a separate module whose source is generated
 by an auxiliary program - but can then be edited by hand if required. There are
 now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
 toupper() in the code.
 
 7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
 make them global. Abolish the function for setting them, as the caller can now
 set them directly.
 
 
 Version 0.92 11-Sep-97
 ----------------------
 
 1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
 (e.g. /a{1,3}/) was broken (I mis-optimized it).
 
 2. Caseless matching was not working in character classes if the characters in
 the pattern were in upper case.
 
 3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
 
 4. Make PCRE_ANCHORED public and accept as a compile option.
 
 5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
 PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
 pass them.
 
 6. Give an error if bad option bits passed at compile or run time.
 
 7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
 pcretest to cause it to pass that flag.
 
 8. Add pcre_info(), to get the number of identifying subpatterns, the stored
 options, and the first character, if set.
 
 9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
 
 
 Version 0.91 10-Sep-97
 ----------------------
 
 1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
 match the empty string as in /(a*)*/. It was looping and ultimately crashing.
 
 2. PCRE was looping on encountering an indefinitely repeated back reference to
 a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
 Perl does - treats the match as successful.
 
 ****