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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 7.7 05-Mar-08  Version 8.32
5    ------------
7    1.  Improved JIT compiler optimizations for first character search and single
8        character iterators.
10    2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
11        Patch by Daniel Richard G.
13    3.  Single character iterator optimizations in the JIT compiler.
16    Version 8.31 06-July-2012
17    -------------------------
19    1.  Fixing a wrong JIT test case and some compiler warnings.
21    2.  Removed a bashism from the RunTest script.
23    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
24        to unsigned type, result still unsigned" that was given by an MS compiler
25        on encountering the code "-sizeof(xxx)".
27    4.  Partial matching support is added to the JIT compiler.
29    5.  Fixed several bugs concerned with partial matching of items that consist
30        of more than one character:
32        (a) /^(..)\1/ did not partially match "aba" because checking references was
33            done on an "all or nothing" basis. This also applied to repeated
34            references.
36        (b) \R did not give a hard partial match if \r was found at the end of the
37            subject.
39        (c) \X did not give a hard partial match after matching one or more
40            characters at the end of the subject.
42        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
43            a partial match for the string "\r".
45        (e) When newline was set to CRLF, the metacharacter "." did not recognize
46            a partial match for a CR character at the end of the subject string.
48    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
49        running pcretest, the text "(JIT)" added to the output whenever JIT is
50        actually used to run the match.
52    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
53        or /S+[+] with a digit between 1 and 7.
55    8.  OP_NOT now supports any UTF character not just single-byte ones.
57    9.  (*MARK) control verb is now supported by the JIT compiler.
59    10. The command "./RunTest list" lists the available tests without actually
60        running any of them. (Because I keep forgetting what they all are.)
64    12. Applied a (slightly modified) user-supplied patch that improves performance
65        when the heap is used for recursion (compiled with --disable-stack-for-
66        recursion). Instead of malloc and free for each heap frame each time a
67        logical recursion happens, frames are retained on a chain and re-used where
68        possible. This sometimes gives as much as 30% improvement.
70    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
71        call.
73    14. As documented, (*COMMIT) is now confined to within a positive assertion.
75    15. It is now possible to link pcretest with libedit as an alternative to
76        libreadline.
78    16. (*COMMIT) control verb is now supported by the JIT compiler.
80    17. The Unicode data tables have been updated to Unicode 6.1.0.
82    18. Added --file-list option to pcregrep.
84    19. Added binary file support to pcregrep, including the -a, --binary-files,
85        -I, and --text options.
87    20. The madvise function is renamed for posix_madvise for QNX compatibility
88        reasons. Fixed by Giuseppe D'Angelo.
90    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
92    22. Changed the option for creating symbolic links for 16-bit man pages from
93        -s to -sf so that re-installing does not cause issues.
95    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
97    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
98        matches in certain environments (the workspace was not being correctly
99        retained). Also added to pcre_dfa_exec() a simple plausibility check on
100        some of the workspace data at the beginning of a restart.
102    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
103        was not doing so when it should - probably a typo introduced by SVN 528
104        (change 8.10/14).
106    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
107        \w+ when the character tables indicated that \x{c4} was a word character.
108        There were several related cases, all because the tests for doing a table
109        lookup were testing for characters less than 127 instead of 255.
111    27. If a pattern contains capturing parentheses that are not used in a match,
112        their slots in the ovector are set to -1. For those that are higher than
113        any matched groups, this happens at the end of processing. In the case when
114        there were back references that the ovector was too small to contain
115        (causing temporary malloc'd memory to be used during matching), and the
116        highest capturing number was not used, memory off the end of the ovector
117        was incorrectly being set to -1. (It was using the size of the temporary
118        memory instead of the true size.)
120    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
121        ovector size, it uses memory at the end of the block that it has got.
123    29. Check for an overlong MARK name and give an error at compile time. The
124        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
126    30. JIT compiler update.
128    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
129        Rill for the patch.
131    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
133    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
135    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
136        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
137        was enabled.
139    35. Improve JIT code generation for greedy plus quantifier.
141    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
142        1 to "aa" instead of to an empty string. The bug affected repeated groups
143        that could potentially match an empty string.
145    37. Optimizing single character iterators in JIT.
147    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
148        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
149        codepoints that are too big for the mode are faulted, and in a UTF mode,
150        disallowed codepoints are also faulted.
152    39. If PCRE was compiled with UTF support, in three places in the DFA
153        matcher there was code that should only have been obeyed in UTF mode, but
154        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
155        processing when bytes with values greater than 127 were present. In 16-bit
156        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
157        both cases the values are those that cannot be the first data item in a UTF
158        character. The three items that might have provoked this were recursions,
159        possessively repeated groups, and atomic groups.
161    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
162        and pcregrep, because some OS require shared objects to be explicitly
163        passed to ld, causing the link step to fail if they are not.
165    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
166        mode, patterns that started with \h* or \R* might be incorrectly matched.
169    Version 8.30 04-February-2012
170    -----------------------------
172    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
173        name is defined in ctype.h.
175    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
176        only in quite long subpatterns.
178    3.  Removed the function pcre_info(), which has been obsolete and deprecated
179        since it was replaced by pcre_fullinfo() in February 2000.
181    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
182        match a (*MARK), and the match failed at the start of the subject, a
183        reference to memory before the start of the subject could occur. This bug
184        was introduced by fix 17 of release 8.21.
186    5.  A reference to an unset group with zero minimum repetition was giving
187        totally wrong answers (in non-JavaScript-compatibility mode). For example,
188        /(another)?(\1?)test/ matched against "hello world test". This bug was
189        introduced in release 8.13.
191    6.  Add support for 16-bit character strings (a large amount of work involving
192        many changes and refactorings).
194    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
195        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
196        from a file.
198    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
199        rounding is not applied in this particular case).
201    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
202        if they appear, or are escaped, in patterns.
204    10. Get rid of a number of -Wunused-but-set-variable warnings.
206    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
207        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
208        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
209        also returns the mark "x". This bug applied to capturing parentheses,
210        non-capturing parentheses, and atomic parentheses. It also applied to some
211        assertions.
213    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
214        information out of configure.ac instead of relying on pcre.h.generic, which
215        is not stored in the repository.
217    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
218        -lreadline.
220    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
222    15. Applied Graycode's patch to put the top-level frame on the stack rather
223        than the heap when not using the stack for recursion. This gives a
224        performance improvement in many cases when recursion is not deep.
226    16. Experimental code added to "pcretest -C" to output the stack frame size.
229    Version 8.21 12-Dec-2011
230    ------------------------
232    1.  Updating the JIT compiler.
234    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
235        are added as well.
237    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
238        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
239        calling _pcre_jit_exec. Some extra comments are added.
241    4.  (*MARK) settings inside atomic groups that do not contain any capturing
242        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
243        was introduced by change 18 for 8.20.
245    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
246        ECMA-262 standard.
248    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
249        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
250        This bug was probably introduced by change 9 of 8.13.
252    7.  While fixing 6 above, I noticed that a number of other items were being
253        incorrectly rejected as "not fixed length". This arose partly because newer
254        opcodes had not been added to the fixed-length checking code. I have (a)
255        corrected the bug and added tests for these items, and (b) arranged for an
256        error to occur if an unknown opcode is encountered while checking for fixed
257        length instead of just assuming "not fixed length". The items that were
258        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
259        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
260        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
262    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
263        being incorrectly compiled and would have given unpredicatble results.
265    9.  A possessively repeated subpattern with minimum repeat count greater than
266        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
267        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
268        the first (A) could occur when it should not.
270    10. Add a cast and remove a redundant test from the code.
272    11. JIT should use pcre_malloc/pcre_free for allocation.
274    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
275        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
276        is anything other than /usr, -L is still shown).
278    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
280    14. Perl does not support \N without a following name in a [] class; PCRE now
281        also gives an error.
283    15. If a forward reference was repeated with an upper limit of around 2000,
284        it caused the error "internal error: overran compiling workspace". The
285        maximum number of forward references (including repeats) was limited by the
286        internal workspace, and dependent on the LINK_SIZE. The code has been
287        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
288        the default depends on LINK_SIZE. There is a new upper limit (for safety)
289        of around 200,000 forward references. While doing this, I also speeded up
290        the filling in of repeated forward references.
292    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
293        incorrectly expecting the subject to contain another "a" after the start.
295    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
296        in the match, the SKIP should be ignored. This was not happening; instead
297        the SKIP was being treated as NOMATCH. For patterns such as
298        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
299        tested.
301    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
302        now much more compatible with Perl, in particular in cases where the result
303        is a non-match for a non-anchored pattern. For example, if
304        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
305        "m", where previously it did not return a name. A side effect of this
306        change is that for partial matches, the last encountered mark name is
307        returned, as for non matches. A number of tests that were previously not
308        Perl-compatible have been moved into the Perl-compatible test files. The
309        refactoring has had the pleasing side effect of removing one argument from
310        the match() function, thus reducing its stack requirements.
312    19. If the /S+ option was used in pcretest to study a pattern using JIT,
313        subsequent uses of /S (without +) incorrectly behaved like /S+.
315    21. Retrieve executable code size support for the JIT compiler and fixing
316        some warnings.
318    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
319        not work when the shorter character appeared right at the end of the
320        subject string.
322    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
323        systems.
325    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
326        output it when the /M option is used in pcretest.
328    25. The CheckMan script was not being included in the distribution. Also, added
329        an explicit "perl" to run Perl scripts from the PrepareRelease script
330        because this is reportedly needed in Windows.
332    26. If study data was being save in a file and studying had not found a set of
333        "starts with" bytes for the pattern, the data written to the file (though
334        never used) was taken from uninitialized memory and so caused valgrind to
335        complain.
337    27. Updated RunTest.bat as provided by Sheri Pierce.
339    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
341    29. Computation of memory usage for the table of capturing group names was
342        giving an unnecessarily large value.
345    Version 8.20 21-Oct-2011
346    ------------------------
348    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
349        a POSIX class. After further experiments with Perl, which convinced me that
350        Perl has bugs and confusions, a closing square bracket is no longer allowed
351        in a POSIX name. This bug also affected patterns with classes that started
352        with full stops.
354    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
355        captured substring, but while checking the failing first alternative,
356        substring 1 is temporarily captured. If the output vector supplied to
357        pcre_exec() was not big enough for this capture, the yield of the function
358        was still zero ("insufficient space for captured substrings"). This cannot
359        be totally fixed without adding another stack variable, which seems a lot
360        of expense for a edge case. However, I have improved the situation in cases
361        such as /(a)(b)x|abc/ matched against "abc", where the return code
362        indicates that fewer than the maximum number of slots in the ovector have
363        been set.
365    3.  Related to (2) above: when there are more back references in a pattern than
366        slots in the output vector, pcre_exec() uses temporary memory during
367        matching, and copies in the captures as far as possible afterwards. It was
368        using the entire output vector, but this conflicts with the specification
369        that only 2/3 is used for passing back captured substrings. Now it uses
370        only the first 2/3, for compatibility. This is, of course, another edge
371        case.
373    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
374        main code base, and can be used by building with --enable-jit. When this is
375        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
376        runtime --no-jit option is given.
378    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
379        ovector, the return from the function was zero, implying that there were
380        other matches that did not fit. The correct "exactly full" value is now
381        returned.
383    6.  If a subpattern that was called recursively or as a subroutine contained
384        (*PRUNE) or any other control that caused it to give a non-standard return,
385        invalid errors such as "Error -26 (nested recursion at the same subject
386        position)" or even infinite loops could occur.
388    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
389        computing the minimum length on reaching *ACCEPT, and so ended up with the
390        wrong value of 1 rather than 0. Further investigation indicates that
391        computing a minimum subject length in the presence of *ACCEPT is difficult
392        (think back references, subroutine calls), and so I have changed the code
393        so that no minimum is registered for a pattern that contains *ACCEPT.
395    8.  If (*THEN) was present in the first (true) branch of a conditional group,
396        it was not handled as intended. [But see 16 below.]
398    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
399        Sheri Pierce.
401    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
402        the first byte in a match must be "a".
404    11. Change 17 for 8.13 increased the recursion depth for patterns like
405        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
406        pattern contains any instances of (*THEN). If it does not, the old
407        optimizations are restored. It would be nice to do this on a per-group
408        basis, but at the moment that is not feasible.
410    12. In some environments, the output of pcretest -C is CRLF terminated. This
411        broke RunTest's code that checks for the link size. A single white space
412        character after the value is now allowed for.
414    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
415        For "fr", it uses the Windows-specific input and output files.
417    14. If (*THEN) appeared in a group that was called recursively or as a
418        subroutine, it did not work as intended. [But see next item.]
420    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
421        pattern fragments (but not containing any | characters). If A and B are
422        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
423        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
424        D. In other words, Perl considers parentheses that do not contain any |
425        characters to be part of a surrounding alternative, whereas PCRE was
426        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
427        differently. PCRE now behaves in the same way as Perl, except in the case
428        of subroutine/recursion calls such as (?1) which have in any case always
429        been different (but PCRE had them first :-).
431    16. Related to 15 above: Perl does not treat the | in a conditional group as
432        creating alternatives. Such a group is treated in the same way as an
433        ordinary group without any | characters when processing (*THEN). PCRE has
434        been changed to match Perl's behaviour.
436    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
437        RunGrepTest script failed.
439    18. Change 22 for version 13 caused atomic groups to use more stack. This is
440        inevitable for groups that contain captures, but it can lead to a lot of
441        stack use in large patterns. The old behaviour has been restored for atomic
442        groups that do not contain any capturing parentheses.
444    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
445        suppress the check for a minimum subject length at run time. (If it was
446        given to pcre_exec() or pcre_dfa_exec() it did work.)
448    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
449        fail to work when decoding hex characters in data strings in EBCDIC
450        environments.
452    21. It appears that in at least one Mac OS environment, the isxdigit() function
453        is implemented as a macro that evaluates to its argument more than once,
454        contravening the C 90 Standard (I haven't checked a later standard). There
455        was an instance in pcretest which caused it to go wrong when processing
456        \x{...} escapes in subject strings. The has been rewritten to avoid using
457        things like p++ in the argument of isxdigit().
460    Version 8.13 16-Aug-2011
461    ------------------------
463    1.  The Unicode data tables have been updated to Unicode 6.0.0.
465    2.  Two minor typos in pcre_internal.h have been fixed.
467    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
468        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
469        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
471    4.  There were a number of related bugs in the code for matching backrefences
472        caselessly in UTF-8 mode when codes for the characters concerned were
473        different numbers of bytes. For example, U+023A and U+2C65 are an upper
474        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
475        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
476        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
477        2-byte code at the end of the subject (it thought there wasn't enough data
478        left).
480    5.  Comprehensive information about what went wrong is now returned by
481        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
482        as the output vector has at least 2 elements. The offset of the start of
483        the failing character and a reason code are placed in the vector.
485    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
486        now returned is for the first byte of the failing character, instead of the
487        last byte inspected. This is an incompatible change, but I hope it is small
488        enough not to be a problem. It makes the returned offset consistent with
489        pcre_exec() and pcre_dfa_exec().
491    7.  pcretest now gives a text phrase as well as the error number when
492        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
493        failure, the offset and reason code are output.
495    8.  When \R was used with a maximizing quantifier it failed to skip backwards
496        over a \r\n pair if the subsequent match failed. Instead, it just skipped
497        back over a single character (\n). This seems wrong (because it treated the
498        two characters as a single entity when going forwards), conflicts with the
499        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
500        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
501        has been changed.
503    9.  Some internal refactoring has changed the processing so that the handling
504        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
505        time (the PCRE_DOTALL option was changed this way some time ago: version
506        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
507        which was always a bit of a fudge. It also means that there is one less
508        argument for the match() function, which reduces its stack requirements
509        slightly. This change also fixes an incompatibility with Perl: the pattern
510        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
512    10. More internal refactoring has drastically reduced the number of recursive
513        calls to match() for possessively repeated groups such as (abc)++ when
514        using pcre_exec().
516    11. While implementing 10, a number of bugs in the handling of groups were
517        discovered and fixed:
519        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
520        (a|)*(?1) gave a compile-time internal error.
521        ((a|)+)+  did not notice that the outer group could match an empty string.
522        (^a|^)+   was not marked as anchored.
523        (.*a|.*)+ was not marked as matching at start or after a newline.
525    12. Yet more internal refactoring has removed another argument from the match()
526        function. Special calls to this function are now indicated by setting a
527        value in a variable in the "match data" data block.
529    13. Be more explicit in pcre_study() instead of relying on "default" for
530        opcodes that mean there is no starting character; this means that when new
531        ones are added and accidentally left out of pcre_study(), testing should
532        pick them up.
534    14. The -s option of pcretest has been documented for ages as being an old
535        synonym of -m (show memory usage). I have changed it to mean "force study
536        for every regex", that is, assume /S for every regex. This is similar to -i
537        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
538        using it. It makes it easier to run collections of tests with and without
539        study enabled, and thereby test pcre_study() more easily. All the standard
540        tests are now run with and without -s (but some patterns can be marked as
541        "never study" - see 20 below).
543    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
544        restoration of the capturing data to the outer values was not happening
545        correctly.
547    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
548        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
549        pattern had matched an empty string, and so incorrectly returned a no
550        match.
552    17. There was optimizing code for the last branch of non-capturing parentheses,
553        and also for the obeyed branch of a conditional subexpression, which used
554        tail recursion to cut down on stack usage. Unfortunately, now that there is
555        the possibility of (*THEN) occurring in these branches, tail recursion is
556        no longer possible because the return has to be checked for (*THEN). These
557        two optimizations have therefore been removed. [But see 8.20/11 above.]
559    18. If a pattern containing \R was studied, it was assumed that \R always
560        matched two bytes, thus causing the minimum subject length to be
561        incorrectly computed because \R can also match just one byte.
563    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
564        was incorrectly computed.
566    20. If /S is present twice on a test pattern in pcretest input, it now
567        *disables* studying, thereby overriding the use of -s on the command line
568        (see 14 above). This is necessary for one or two tests to keep the output
569        identical in both cases.
571    21. When (*ACCEPT) was used in an assertion that matched an empty string and
572        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
574    22. When an atomic group that contained a capturing parenthesis was
575        successfully matched, but the branch in which it appeared failed, the
576        capturing was not being forgotten if a higher numbered group was later
577        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
578        group 1 to "a", when in fact it should be unset. This applied to multi-
579        branched capturing and non-capturing groups, repeated or not, and also to
580        positive assertions (capturing in negative assertions does not happen
581        in PCRE) and also to nested atomic groups.
583    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
584        subject after a captured substring, to make it easier to tell which of a
585        number of identical substrings has been captured.
587    24. The way atomic groups are processed by pcre_exec() has been changed so that
588        if they are repeated, backtracking one repetition now resets captured
589        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
590        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
591        "aaa". Previously, it would have been "a". As part of this code
592        refactoring, the way recursive calls are handled has also been changed.
594    25. If an assertion condition captured any substrings, they were not passed
595        back unless some other capturing happened later. For example, if
596        (?(?=(a))a) was matched against "a", no capturing was returned.
598    26. When studying a pattern that contained subroutine calls or assertions,
599        the code for finding the minimum length of a possible match was handling
600        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
601        group 1 called group 2 while simultaneously a separate group 2 called group
602        1). A stack overflow occurred in this case. I have fixed this by limiting
603        the recursion depth to 10.
605    27. Updated RunTest.bat in the distribution to the version supplied by Tom
606        Fortmann. This supports explicit test numbers on the command line, and has
607        argument validation and error reporting.
609    28. An instance of \X with an unlimited repeat could fail if at any point the
610        first character it looked at was a mark character.
612    29. Some minor code refactoring concerning Unicode properties and scripts
613        should reduce the stack requirement of match() slightly.
615    30. Added the '=' option to pcretest to check the setting of unused capturing
616        slots at the end of the pattern, which are documented as being -1, but are
617        not included in the return count.
619    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
620        compiled something random. Now it gives a compile-time error (as does
621        Perl).
623    32. A *MARK encountered during the processing of a positive assertion is now
624        recorded and passed back (compatible with Perl).
626    33. If --only-matching or --colour was set on a pcregrep call whose pattern
627        had alternative anchored branches, the search for a second match in a line
628        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
629        matched the line "0102" twice. The same bug affected patterns that started
630        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
631        twice.
633    34. Previously, PCRE did not allow quantification of assertions. However, Perl
634        does, and because of capturing effects, quantifying parenthesized
635        assertions may at times be useful. Quantifiers are now allowed for
636        parenthesized assertions.
638    35. A minor code tidy in pcre_compile() when checking options for \R usage.
640    36. \g was being checked for fancy things in a character class, when it should
641        just be a literal "g".
643    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
644        appearance of a nested POSIX class supersedes an apparent external class.
645        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
646        unescaped square brackets may also appear as part of class names. For
647        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
648        more like Perl. (But see 8.20/1 above.)
650    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
651        was because it thought it was \N{name}, which is not supported).
653    39. Add minix to OS list not supporting the -S option in pcretest.
655    40. PCRE tries to detect cases of infinite recursion at compile time, but it
656        cannot analyze patterns in sufficient detail to catch mutual recursions
657        such as ((?1))((?2)). There is now a runtime test that gives an error if a
658        subgroup is called recursively as a subpattern for a second time at the
659        same position in the subject string. In previous releases this might have
660        been caught by the recursion limit, or it might have run out of stack.
662    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
663        happen only once. PCRE was, however incorrectly giving a compile time error
664        "recursive call could loop indefinitely" because it cannot analyze the
665        pattern in sufficient detail. The compile time test no longer happens when
666        PCRE is compiling a conditional subpattern, but actual runaway loops are
667        now caught at runtime (see 40 above).
669    42. It seems that Perl allows any characters other than a closing parenthesis
670        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
671        has been changed to be the same.
673    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
674        as not to get warnings when autogen.sh is called. Also changed
675        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
677    44. To help people who use pcregrep to scan files containing exceedingly long
678        lines, the following changes have been made:
680        (a) The default value of the buffer size parameter has been increased from
681            8K to 20K. (The actual buffer used is three times this size.)
683        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
684            PCRE is built.
686        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
687            to be set at run time.
689        (d) Numerical values in pcregrep options can be followed by K or M, for
690            example --buffer-size=50K.
692        (e) If a line being scanned overflows pcregrep's buffer, an error is now
693            given and the return code is set to 2.
695    45. Add a pointer to the latest mark to the callout data block.
697    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
698        partial match of an empty string instead of no match. This was specific to
699        the use of ".".
701    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
702        complete match instead of a partial match. This bug was dependent on both
703        the PCRE_UTF8 and PCRE_DOTALL options being set.
705    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
706        starting byte set, because \b was not being ignored.
709    Version 8.12 15-Jan-2011
710    ------------------------
712    1.  Fixed some typos in the markup of the man pages, and wrote a script that
713        checks for such things as part of the documentation building process.
715    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
716        --match-limit and --recursion-limit options (added for 8.11). In
717        particular, this made one of the standard tests fail. (The integer value
718        went into the wrong half of a long int.)
720    3.  If the --colour option was given to pcregrep with -v (invert match), it
721        did strange things, either producing crazy output, or crashing. It should,
722        of course, ignore a request for colour when reporting lines that do not
723        match.
725    4.  Another pcregrep bug caused similar problems if --colour was specified with
726        -M (multiline) and the pattern match finished with a line ending.
728    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
729        matched in multiline mode, the following line was shown as part of the
730        match. This seems wrong, so I have changed it.
732    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
733        the check for further matches in the same line (so they could be coloured)
734        to overrun the end of the current line. If another match was found, it was
735        incorrectly shown (and then shown again when found in the next line).
737    7.  If pcregrep was compiled under Windows, there was a reference to the
738        function pcregrep_exit() before it was defined. I am assuming this was
739        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
740        reported by a user. I've moved the definition above the reference.
743    Version 8.11 10-Dec-2010
744    ------------------------
746    1.  (*THEN) was not working properly if there were untried alternatives prior
747        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
748        backtracked to try for "b" instead of moving to the next alternative branch
749        at the same level (in this case, to look for "c"). The Perl documentation
750        is clear that when (*THEN) is backtracked onto, it goes to the "next
751        alternative in the innermost enclosing group".
753    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
754        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
755        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
756        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
757        (*THEN).
759    3.  If \s appeared in a character class, it removed the VT character from
760        the class, even if it had been included by some previous item, for example
761        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
762        of \s, but is part of the POSIX "space" class.)
764    4.  A partial match never returns an empty string (because you can always
765        match an empty string at the end of the subject); however the checking for
766        an empty string was starting at the "start of match" point. This has been
767        changed to the "earliest inspected character" point, because the returned
768        data for a partial match starts at this character. This means that, for
769        example, /(?<=abc)def/ gives a partial match for the subject "abc"
770        (previously it gave "no match").
772    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
773        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
774        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
775        has an implication that the given string is incomplete (because a partial
776        match is preferred over a full match). For this reason, these items now
777        give a partial match in this situation. [Aside: previously, the one case
778        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
779        match rather than a full match, which was wrong by the old rules, but is
780        now correct.]
782    6.  There was a bug in the handling of #-introduced comments, recognized when
783        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
784        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
785        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
786        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
787        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
788        places in pcre_compile().
790    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
791        comments when looking ahead for named forward references to subpatterns,
792        the only newline sequence it recognized was NL. It now handles newlines
793        according to the set newline convention.
795    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
796        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
797        cater for a lack of strerror(). These oversights have been fixed.
799    9.  Added --match-limit and --recursion-limit to pcregrep.
801    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
803    11. When the -o option was used, pcregrep was setting a return code of 1, even
804        when matches were found, and --line-buffered was not being honoured.
806    12. Added an optional parentheses number to the -o and --only-matching options
807        of pcregrep.
809    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
810        can match an empty string. The code to do it in pcretest and pcredemo
811        needed fixing:
813        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
814            only one byte after an empty string match just before CRLF (this case
815            just got forgotten; "any" and "anycrlf" were OK).
817        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
818            mode when an empty string match preceded an ASCII character followed by
819            a non-ASCII character. (The code for advancing by one character rather
820            than one byte was nonsense.)
822        (c) The pcredemo.c sample program did not have any code at all to handle
823            the cases when CRLF is a valid newline sequence.
825    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
826        as a starting offset was within the subject string. There is now a new
827        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
828        negative or greater than the length of the string. In order to test this,
829        pcretest is extended to allow the setting of negative starting offsets.
831    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
832        starting offset points to the beginning of a UTF-8 character was
833        unnecessarily clumsy. I tidied it up.
835    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
836        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
838    17. Nobody had reported that the --include_dir option, which was added in
839        release 7.7 should have been called --include-dir (hyphen, not underscore)
840        for compatibility with GNU grep. I have changed it to --include-dir, but
841        left --include_dir as an undocumented synonym, and the same for
842        --exclude-dir, though that is not available in GNU grep, at least as of
843        release 2.5.4.
845    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
846        characters from a string of bytes) have been redefined so as not to use
847        loops, in order to improve performance in some environments. At the same
848        time, I abstracted some of the common code into auxiliary macros to save
849        repetition (this should not affect the compiled code).
851    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
852        compile-time error is now given if \c is not followed by an ASCII
853        character, that is, a byte less than 128. (In EBCDIC mode, the code is
854        different, and any byte value is allowed.)
856    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
857        START_OPTIMIZE option, which is now allowed at compile time - but just
858        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
859        to pcregrep and other applications that have no direct access to PCRE
860        options. The new /Y option in pcretest sets this option when calling
861        pcre_compile().
863    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
864        back references. Groups containing recursive back references were forced to
865        be atomic by that change, but in the case of named groups, the amount of
866        memory required was incorrectly computed, leading to "Failed: internal
867        error: code overflow". This has been fixed.
869    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
870        pcretest.c, to avoid build problems in some Borland environments.
873    Version 8.10 25-Jun-2010
874    ------------------------
876    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
877        THEN.
879    2.  (*ACCEPT) was not working when inside an atomic group.
881    3.  Inside a character class, \B is treated as a literal by default, but
882        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
883        causes the error). The code is unchanged, but I tidied the documentation.
885    4.  Inside a character class, PCRE always treated \R and \X as literals,
886        whereas Perl faults them if its -w option is set. I have changed PCRE so
887        that it faults them when PCRE_EXTRA is set.
889    5.  Added support for \N, which always matches any character other than
890        newline. (It is the same as "." when PCRE_DOTALL is not set.)
892    6.  When compiling pcregrep with newer versions of gcc which may have
893        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
894        declared with attribute warn_unused_result" were given. Just casting the
895        result to (void) does not stop the warnings; a more elaborate fudge is
896        needed. I've used a macro to implement this.
898    7.  Minor change to pcretest.c to avoid a compiler warning.
900    8.  Added four artifical Unicode properties to help with an option to make
901        \s etc use properties (see next item). The new properties are: Xan
902        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
904    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
905        use Unicode properties. (*UCP) at the start of a pattern can be used to set
906        this option. Modified pcretest to add /W to test this facility. Added
907        REG_UCP to make it available via the POSIX interface.
909    10. Added --line-buffered to pcregrep.
911    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
912        studied, and the match started with a letter with a code point greater than
913        127 whose first byte was different to the first byte of the other case of
914        the letter, the other case of this starting letter was not recognized
915        (#976).
917    12. If a pattern that was studied started with a repeated Unicode property
918        test, for example, \p{Nd}+, there was the theoretical possibility of
919        setting up an incorrect bitmap of starting bytes, but fortunately it could
920        not have actually happened in practice until change 8 above was made (it
921        added property types that matched character-matching opcodes).
923    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
924        possible starting bytes for non-anchored patterns.
926    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
927        \R, and also a number of cases that involve Unicode properties, both
928        explicit and implicit when PCRE_UCP is set.
930    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
931        input, it could crash or give wrong results if characters with values
932        greater than 0xc0 were present in the subject string. (Detail: it assumed
933        UTF-8 input when processing these items.)
935    16. Added a lot of (int) casts to avoid compiler warnings in systems where
936        size_t is 64-bit (#991).
938    17. Added a check for running out of memory when PCRE is compiled with
939        --disable-stack-for-recursion (#990).
941    18. If the last data line in a file for pcretest does not have a newline on
942        the end, a newline was missing in the output.
944    19. The default pcre_chartables.c file recognizes only ASCII characters (values
945        less than 128) in its various bitmaps. However, there is a facility for
946        generating tables according to the current locale when PCRE is compiled. It
947        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
948        characters, are recognized by isspace() and therefore were getting set in
949        these tables, and indeed these tables seem to approximate to ISO 8859. This
950        caused a problem in UTF-8 mode when pcre_study() was used to create a list
951        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
952        which of course cannot start UTF-8 characters. I have changed the code so
953        that only real ASCII characters (less than 128) and the correct starting
954        bytes for UTF-8 encodings are set for characters greater than 127 when in
955        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
956        altogether.)
958    20. Added the /T option to pcretest so as to be able to run tests with non-
959        standard character tables, thus making it possible to include the tests
960        used for 19 above in the standard set of tests.
962    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
963        reference to a subpattern the other side of a comment that contains an
964        opening parenthesis caused either an internal compiling error, or a
965        reference to the wrong subpattern.
968    Version 8.02 19-Mar-2010
969    ------------------------
971    1.  The Unicode data tables have been updated to Unicode 5.2.0.
973    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
974        configured.
976    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
977        original author of that file, following a query about its status.
979    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
980        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
982    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
983        quantifier applied to a forward-referencing subroutine call, could compile
984        incorrect code or give the error "internal error: previously-checked
985        referenced subpattern not found".
987    6.  Both MS Visual Studio and Symbian OS have problems with initializing
988        variables to point to external functions. For these systems, therefore,
989        pcre_malloc etc. are now initialized to local functions that call the
990        relevant global functions.
992    7.  There were two entries missing in the vectors called coptable and poptable
993        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
994        I've fixed the data, and added a kludgy way of testing at compile time that
995        the lengths are correct (equal to the number of opcodes).
997    8.  Following on from 7, I added a similar kludge to check the length of the
998        eint vector in pcreposix.c.
1000    9.  Error texts for pcre_compile() are held as one long string to avoid too
1001        much relocation at load time. To find a text, the string is searched,
1002        counting zeros. There was no check for running off the end of the string,
1003        which could happen if a new error number was added without updating the
1004        string.
1006    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
1008    11. \K was not working if it appeared in an atomic group or in a group that
1009        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
1010        \K is "not well defined" if used in an assertion. PCRE now accepts it if
1011        the assertion is positive, but not if it is negative.
1013    12. Change 11 fortuitously reduced the size of the stack frame used in the
1014        "match()" function of pcre_exec.c by one pointer. Forthcoming
1015        implementation of support for (*MARK) will need an extra pointer on the
1016        stack; I have reserved it now, so that the stack frame size does not
1017        decrease.
1019    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
1020        item in branch that calls a recursion is a subroutine call - as in the
1021        second branch in the above example - was incorrectly given the compile-
1022        time error "recursive call could loop indefinitely" because pcre_compile()
1023        was not correctly checking the subroutine for matching a non-empty string.
1025    14. The checks for overrunning compiling workspace could trigger after an
1026        overrun had occurred. This is a "should never occur" error, but it can be
1027        triggered by pathological patterns such as hundreds of nested parentheses.
1028        The checks now trigger 100 bytes before the end of the workspace.
1030    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
1033    Version 8.01 19-Jan-2010
1034    ------------------------
1036    1.  If a pattern contained a conditional subpattern with only one branch (in
1037        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
1038        computed the wrong minimum data length (which is of course zero for such
1039        subpatterns). This could cause incorrect "no match" results.
1041    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
1042        the pattern is reset in the first branch, pcre_compile() failed with
1043        "internal error: code overflow at offset...". This happened only when
1044        the reset was to the original external option setting. (An optimization
1045        abstracts leading options settings into an external setting, which was the
1046        cause of this.)
1048    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
1049        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
1050        assertion pattern did not match (meaning that the assertion was true), it
1051        was incorrectly treated as false if the SKIP had been reached during the
1052        matching. This also applied to assertions used as conditions.
1054    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
1055        assertion subpattern, including such a pattern used as a condition,
1056        unpredictable results occurred, instead of the error return
1059    5.  The C++ GlobalReplace function was not working like Perl for the special
1060        situation when an empty string is matched. It now does the fancy magic
1061        stuff that is necessary.
1063    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
1064        removed. (These were left over from very, very early versions of PCRE.)
1066    7.  Some cosmetic changes to the code to make life easier when compiling it
1067        as part of something else:
1069        (a) Change DEBUG to PCRE_DEBUG.
1071        (b) In pcre_compile(), rename the member of the "branch_chain" structure
1072            called "current" as "current_branch", to prevent a collision with the
1073            Linux macro when compiled as a kernel module.
1075        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
1076            prevent a collision with the Linux macro when compiled as a kernel
1077            module.
1079    8.  In pcre_compile() there are some checks for integer overflows that used to
1080        cast potentially large values to (double). This has been changed to that
1081        when building, a check for int64_t is made, and if it is found, it is used
1082        instead, thus avoiding the use of floating point arithmetic. (There is no
1083        other use of FP in PCRE.) If int64_t is not found, the fallback is to
1084        double.
1086    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
1087        2005 (difference between two addresses compared to an unsigned value).
1089    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
1090        custom one, because of the following reported problem in Windows:
1092          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
1093              under Win32.
1094          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
1095              therefore missing the function definition.
1096          - The compiler thus generates a "C" signature for the test function.
1097          - The linker fails to find the "C" function.
1098          - PCRE fails to configure if asked to do so against libbz2.
1100    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
1101        messages were output:
1103          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
1104          rerunning libtoolize, to keep the correct libtool macros in-tree.
1105          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
1107        I have done both of these things.
1109    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
1110        most of the time, it *can* run out if it is given a pattern that contains a
1111        runaway infinite recursion. I updated the discussion in the pcrestack man
1112        page.
1114    13. Now that we have gone to the x.xx style of version numbers, the minor
1115        version may start with zero. Using 08 or 09 is a bad idea because users
1116        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
1117        interpreted as invalid octal numbers. I've updated the previous comment in
1118        configure.ac, and also added a check that gives an error if 08 or 09 are
1119        used.
1121    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
1122        causing partial matching to fail when the end of the subject matched \W
1123        in a UTF-8 pattern where \W was quantified with a minimum of 3.
1125    15. There were some discrepancies between the declarations in pcre_internal.h
1126        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
1127        their definitions. The declarations used "const uschar *" and the
1128        definitions used USPTR. Even though USPTR is normally defined as "const
1129        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
1130        reported that: "This difference in casting confuses some C++ compilers, for
1131        example, SunCC recognizes above declarations as different functions and
1132        generates broken code for hbpcre." I have changed the declarations to use
1133        USPTR.
1135    16. GNU libtool is named differently on some systems. The autogen.sh script now
1136        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
1137        (FreeBSD).
1139    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
1140        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
1141        comment: "Figure out how to create a longlong from a string: strtoll and
1142        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
1143        instance, but it only takes 2 args instead of 3!"
1145    18. A subtle bug concerned with back references has been fixed by a change of
1146        specification, with a corresponding code fix. A pattern such as
1147        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
1148        refers, was giving matches when it shouldn't. For example, xa=xaaa would
1149        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
1150        same bug. Such groups have to be quantified to be useful, or contained
1151        inside another quantified group. (If there's no repetition, the reference
1152        can never match.) The problem arises because, having left the group and
1153        moved on to the rest of the pattern, a later failure that backtracks into
1154        the group uses the captured value from the final iteration of the group
1155        rather than the correct earlier one. I have fixed this in PCRE by forcing
1156        any group that contains a reference to itself to be an atomic group; that
1157        is, there cannot be any backtracking into it once it has completed. This is
1158        similar to recursive and subroutine calls.
1161    Version 8.00 19-Oct-09
1162    ----------------------
1164    1.  The table for translating pcre_compile() error codes into POSIX error codes
1165        was out-of-date, and there was no check on the pcre_compile() error code
1166        being within the table. This could lead to an OK return being given in
1167        error.
1169    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
1170        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
1171        in a Windows environment.
1173    3.  The pcregrep --count option prints the count for each file even when it is
1174        zero, as does GNU grep. However, pcregrep was also printing all files when
1175        --files-with-matches was added. Now, when both options are given, it prints
1176        counts only for those files that have at least one match. (GNU grep just
1177        prints the file name in this circumstance, but including the count seems
1178        more useful - otherwise, why use --count?) Also ensured that the
1179        combination -clh just lists non-zero counts, with no names.
1181    4.  The long form of the pcregrep -F option was incorrectly implemented as
1182        --fixed_strings instead of --fixed-strings. This is an incompatible change,
1183        but it seems right to fix it, and I didn't think it was worth preserving
1184        the old behaviour.
1186    5.  The command line items --regex=pattern and --regexp=pattern were not
1187        recognized by pcregrep, which required --regex pattern or --regexp pattern
1188        (with a space rather than an '='). The man page documented the '=' forms,
1189        which are compatible with GNU grep; these now work.
1191    6.  No libpcreposix.pc file was created for pkg-config; there was just
1192        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
1194    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
1195        when UCP support is not needed, by modifying the Python script that
1196        generates it from Unicode data files. This should not matter if the module
1197        is correctly used as a library, but I received one complaint about 50K of
1198        unwanted data. My guess is that the person linked everything into his
1199        program rather than using a library. Anyway, it does no harm.
1201    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
1202        was a minimum greater than 1 for a wide character in a possessive
1203        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
1204        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
1205        character. Chaos in the form of incorrect output or a compiling loop could
1206        result.
1208    9.  The restrictions on what a pattern can contain when partial matching is
1209        requested for pcre_exec() have been removed. All patterns can now be
1210        partially matched by this function. In addition, if there are at least two
1211        slots in the offset vector, the offset of the earliest inspected character
1212        for the match and the offset of the end of the subject are set in them when
1213        PCRE_ERROR_PARTIAL is returned.
1215    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
1216        synonymous with PCRE_PARTIAL, for backwards compatibility, and
1217        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
1218        and may be more useful for multi-segment matching.
1220    11. Partial matching with pcre_exec() is now more intuitive. A partial match
1221        used to be given if ever the end of the subject was reached; now it is
1222        given only if matching could not proceed because another character was
1223        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
1224        string "Z", which now yields "no match" instead of "partial match". In the
1225        case of pcre_dfa_exec(), "no match" is given if every matching path for the
1226        final character ended with (*FAIL).
1228    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
1229        if the pattern had a "must contain" character that was already found in the
1230        earlier partial match, unless partial matching was again requested. For
1231        example, with the pattern /dog.(body)?/, the "must contain" character is
1232        "g". If the first part-match was for the string "dog", restarting with
1233        "sbody" failed. This bug has been fixed.
1235    13. The string returned by pcre_dfa_exec() after a partial match has been
1236        changed so that it starts at the first inspected character rather than the
1237        first character of the match. This makes a difference only if the pattern
1238        starts with a lookbehind assertion or \b or \B (\K is not supported by
1239        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1240        matching functions compatible, and I think it's the right thing to do.
1242    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1243        so that the demonstration program is easily available in environments where
1244        PCRE has not been installed from source.
1246    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1247        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1248        library.
1250    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1251        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1252        is not the first non-POSIX option to be added. Clearly some people find
1253        these options useful.
1255    17. If a caller to the POSIX matching function regexec() passes a non-zero
1256        value for nmatch with a NULL value for pmatch, the value of
1257        nmatch is forced to zero.
1259    18. RunGrepTest did not have a test for the availability of the -u option of
1260        the diff command, as RunTest does. It now checks in the same way as
1261        RunTest, and also checks for the -b option.
1263    19. If an odd number of negated classes containing just a single character
1264        interposed, within parentheses, between a forward reference to a named
1265        subpattern and the definition of the subpattern, compilation crashed with
1266        an internal error, complaining that it could not find the referenced
1267        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1268        [The bug was that it was starting one character too far in when skipping
1269        over the character class, thus treating the ] as data rather than
1270        terminating the class. This meant it could skip too much.]
1272    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1273        /g option in pcretest when the pattern contains \K, which makes it possible
1274        to have an empty string match not at the start, even when the pattern is
1275        anchored. Updated pcretest and pcredemo to use this option.
1277    21. If the maximum number of capturing subpatterns in a recursion was greater
1278        than the maximum at the outer level, the higher number was returned, but
1279        with unset values at the outer level. The correct (outer level) value is
1280        now given.
1282    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1283        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1284        make it do so. The string so far is captured, making this feature
1285        compatible with Perl.
1287    23. The tests have been re-organized, adding tests 11 and 12, to make it
1288        possible to check the Perl 5.10 features against Perl 5.10.
1290    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1291        pattern matches a fixed length string. PCRE did not allow this; now it
1292        does. Neither allows recursion.
1294    25. I finally figured out how to implement a request to provide the minimum
1295        length of subject string that was needed in order to match a given pattern.
1296        (It was back references and recursion that I had previously got hung up
1297        on.) This code has now been added to pcre_study(); it finds a lower bound
1298        to the length of subject needed. It is not necessarily the greatest lower
1299        bound, but using it to avoid searching strings that are too short does give
1300        some useful speed-ups. The value is available to calling programs via
1301        pcre_fullinfo().
1303    26. While implementing 25, I discovered to my embarrassment that pcretest had
1304        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1305        study optimizations had never been tested with that matching function.
1306        Oops. What is worse, even when it was passed study data, there was a bug in
1307        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1308        were also very few tests of studied patterns with pcre_dfa_exec().
1310    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1311        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1312        on the other side of the coin, they are no longer allowed to have different
1313        names, because these cannot be distinguished in PCRE, and this has caused
1314        confusion. (This is a difference from Perl.)
1316    28. When duplicate subpattern names are present (necessarily with different
1317        numbers, as required by 27 above), and a test is made by name in a
1318        conditional pattern, either for a subpattern having been matched, or for
1319        recursion in such a pattern, all the associated numbered subpatterns are
1320        tested, and the overall condition is true if the condition is true for any
1321        one of them. This is the way Perl works, and is also more like the way
1322        testing by number works.
1325    Version 7.9 11-Apr-09
1326    ---------------------
1328    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
1329        (pcretest), all targets were linked against these libraries. This included
1330        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
1331        libraries. This caused unwanted dependencies to be created. This problem
1332        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
1333        pcretest is linked with readline.
1335    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
1336        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
1337        moved outside it again, because FALSE and TRUE are already defined in AIX,
1338        but BOOL is not.
1340    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
1341        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
1343    4.  The pcregrep documentation said spaces were inserted as well as colons (or
1344        hyphens) following file names and line numbers when outputting matching
1345        lines. This is not true; no spaces are inserted. I have also clarified the
1346        wording for the --colour (or --color) option.
1348    5.  In pcregrep, when --colour was used with -o, the list of matching strings
1349        was not coloured; this is different to GNU grep, so I have changed it to be
1350        the same.
1352    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
1353        each matching line was coloured. Now it goes on to look for further matches
1354        of any of the test patterns, which is the same behaviour as GNU grep.
1356    7.  A pattern that could match an empty string could cause pcregrep to loop; it
1357        doesn't make sense to accept an empty string match in pcregrep, so I have
1358        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
1359        seems to be how GNU grep behaves.
1361    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
1362        start or after a newline", because the conditional assertion was not being
1363        correctly handled. The rule now is that both the assertion and what follows
1364        in the first alternative must satisfy the test.
1366    9.  If auto-callout was enabled in a pattern with a conditional group whose
1367        condition was an assertion, PCRE could crash during matching, both with
1368        pcre_exec() and pcre_dfa_exec().
1370    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
1371        used for matching.
1373    11. Unicode property support in character classes was not working for
1374        characters (bytes) greater than 127 when not in UTF-8 mode.
1376    12. Added the -M command line option to pcretest.
1378    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
1380    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
1382    16. Added comments and documentation about mis-use of no_arg in the C++
1383        wrapper.
1385    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
1386        from Martin Jerabek that uses macro names for all relevant character and
1387        string constants.
1389    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
1390        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
1391        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
1392        these, but not everybody uses configure.
1394    19. A conditional group that had only one branch was not being correctly
1395        recognized as an item that could match an empty string. This meant that an
1396        enclosing group might also not be so recognized, causing infinite looping
1397        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
1398        with the subject "ab", where knowledge that the repeated group can match
1399        nothing is needed in order to break the loop.
1401    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
1402        exec(), but without supplying a callout function, matching went wrong.
1404    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
1405        leak if the size of the offset vector was greater than 30. When the vector
1406        is smaller, the saved offsets during recursion go onto a local stack
1407        vector, but for larger vectors malloc() is used. It was failing to free
1408        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
1409        error, in fact).
1411    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
1412        heapframe that is used only when UTF-8 support is enabled. This caused no
1413        problem, but was untidy.
1415    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
1416        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
1417        included within another project.
1419    24. Steven Van Ingelgem's patches to add more options to the CMake support,
1420        slightly modified by me:
1422          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
1423              not building pcregrep.
1425          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
1426              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
1428    25. Forward references, both numeric and by name, in patterns that made use of
1429        duplicate group numbers, could behave incorrectly or give incorrect errors,
1430        because when scanning forward to find the reference group, PCRE was not
1431        taking into account the duplicate group numbers. A pattern such as
1432        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
1434    26. Changed a few more instances of "const unsigned char *" to USPTR, making
1435        the feature of a custom pointer more persuasive (as requested by a user).
1437    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
1438        pcretest.c, inside #ifndefs, because it seems they are sometimes already
1439        pre-defined.
1441    28. Added support for (*UTF8) at the start of a pattern.
1443    29. Arrange for flags added by the "release type" setting in CMake to be shown
1444        in the configuration summary.
1447    Version 7.8 05-Sep-08
1448    ---------------------
1450    1.  Replaced UCP searching code with optimized version as implemented for Ad
1451        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
1452        stage table and inline lookup instead of a function, giving speed ups of 2
1453        to 5 times on some simple patterns that I tested. Permission was given to
1454        distribute the MultiStage2.py script that generates the tables (it's not in
1455        the tarball, but is in the Subversion repository).
1457    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
1458        scripts.
1460    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
1461        a group with a zero qualifier. The result of the study could be incorrect,
1462        or the function might crash, depending on the pattern.
1464    4.  Caseless matching was not working for non-ASCII characters in back
1465        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
1466        It now works when Unicode Property Support is available.
1468    5.  In pcretest, an escape such as \x{de} in the data was always generating
1469        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
1470        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
1471        truncation.
1473    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
1475    7.  Added two (int) casts to pcregrep when printing the difference of two
1476        pointers, in case they are 64-bit values.
1478    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
1479        test 2 if it fails.
1481    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
1482        and a #define of that name to empty if it is not externally set. This is to
1483        allow users of MSVC to set it if necessary.
1485    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
1486        the convenience functions in the pcre_get.c source file.
1488    11. An option change at the start of a pattern that had top-level alternatives
1489        could cause overwriting and/or a crash. This command provoked a crash in
1490        some environments:
1492          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
1494        This potential security problem was recorded as CVE-2008-2371.
1496    12. For a pattern where the match had to start at the beginning or immediately
1497        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
1498        pcre_dfa_exec() could read past the end of the passed subject if there was
1499        no match. To help with detecting such bugs (e.g. with valgrind), I modified
1500        pcretest so that it places the subject at the end of its malloc-ed buffer.
1502    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
1503        exec() might read past the end of the data buffer in UTF-8 mode.
1505    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
1506        the data contained the byte 0x85 as part of a UTF-8 character within its
1507        first line. This applied both to normal and DFA matching.
1509    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
1510        /^[^d]*?$/8 failed to match "abc".
1512    16. Added a missing copyright notice to pcrecpp_internal.h.
1514    17. Make it more clear in the documentation that values returned from
1515        pcre_exec() in ovector are byte offsets, not character counts.
1517    18. Tidied a few places to stop certain compilers from issuing warnings.
1519    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
1520        supplied by Stefan Weber. I made a further small update for 7.8 because
1521        there is a change of source arrangements: the pcre_searchfuncs.c module is
1522        replaced by pcre_ucd.c.
1525    Version 7.7 07-May-08
1526  ---------------------  ---------------------
1528  1.  Applied Craig's patch to sort out a long long problem: "If we can't convert  1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
1529      a string to a long long, pretend we don't even have a long long." This is      a string to a long long, pretend we don't even have a long long." This is
1530      done by checking for the strtoq, strtoll, and _strtoi64 functions.      done by checking for the strtoq, strtoll, and _strtoi64 functions.
1532  2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with  2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
1533      pre-7.6 versions, which defined a global no_arg variable instead of putting      pre-7.6 versions, which defined a global no_arg variable instead of putting
1534      it in the RE class.      it in the RE class. (See also #8 below.)
1536    3.  Remove a line of dead code, identified by coverity and reported by Nuno
1537        Lopes.
1539    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
1541        (1) The include/exclude patterns were being applied to the whole pathnames
1542            of files, instead of just to the final components.
1544        (2) If there was more than one level of directory, the subdirectories were
1545            skipped unless they satisfied the include/exclude conditions. This is
1546            inconsistent with GNU grep (and could even be seen as contrary to the
1547            pcregrep specification - which I improved to make it absolutely clear).
1548            The action now is always to scan all levels of directory, and just
1549            apply the include/exclude patterns to regular files.
1551    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
1552        --exclude_dir in the tests to avoid scanning .svn directories.
1554    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
1555        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
1556        doesn't support NULs in patterns.
1558    7.  Added some missing "const"s to declarations of static tables in
1559        pcre_compile.c and pcre_dfa_exec.c.
1561    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
1562        caused by fix #2  above. (Subsequently also a second patch to fix the
1563        first patch. And a third patch - this was a messy problem.)
1565    9.  Applied Craig's patch to remove the use of push_back().
1567    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
1568        matching function regexec().
1570    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
1571        which, however, unlike Perl's \g{...}, are subroutine calls, not back
1572        references. PCRE supports relative numbers with this syntax (I don't think
1573        Oniguruma does).
1575    12. Previously, a group with a zero repeat such as (...){0} was completely
1576        omitted from the compiled regex. However, this means that if the group
1577        was called as a subroutine from elsewhere in the pattern, things went wrong
1578        (an internal error was given). Such groups are now left in the compiled
1579        pattern, with a new opcode that causes them to be skipped at execution
1580        time.
1582    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
1583        to the way PCRE behaves:
1585        (a) A lone ] character is dis-allowed (Perl treats it as data).
1587        (b) A back reference to an unmatched subpattern matches an empty string
1588            (Perl fails the current match path).
1590        (c) A data ] in a character class must be notated as \] because if the
1591            first data character in a class is ], it defines an empty class. (In
1592            Perl it is not possible to have an empty class.) The empty class []
1593            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
1594            The negative empty class [^] matches any one character, independently
1595            of the DOTALL setting.
1597    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
1598        non-existent subpattern following a character class starting with ']' and
1599        containing () gave an internal compiling error instead of "reference to
1600        non-existent subpattern". Fortunately, when the pattern did exist, the
1601        compiled code was correct. (When scanning forwards to check for the
1602        existencd of the subpattern, it was treating the data ']' as terminating
1603        the class, so got the count wrong. When actually compiling, the reference
1604        was subsequently set up correctly.)
1606    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
1607        it was being rejected as not supported by pcre_dfa_exec(), even though
1608        other assertions are supported. I have made pcre_dfa_exec() support
1609        (*FAIL).
1611    16. The implementation of 13c above involved the invention of a new opcode,
1612        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
1613        cannot be changed at match time, I realized I could make a small
1614        improvement to matching performance by compiling OP_ALLANY instead of
1615        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
1616        on the OP_ANY path.
1618    17. Compiling pcretest on Windows with readline support failed without the
1619        following two fixes: (1) Make the unistd.h include conditional on
1620        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
1622    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
1623        ncurses library to be included for pcretest when ReadLine support is
1624        requested, but also to allow for it to be overridden. This patch came from
1625        Daniel Bergström.
1627    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
1628        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
1629        any errors with the current Unicode tables. Thanks to Peter Kankowski for
1630        spotting this.
1633  Version 7.6 28-Jan-08  Version 7.6 28-Jan-08

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