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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.10 16-Jun-2010  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.
15    4.  Improved JIT compiler optimizations for character ranges.
17    5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
18        Reported by Giuseppe D'Angelo.
20    6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
21        of a line, was being set incorrectly in cases where .* appeared inside
22        atomic brackets at the start of a pattern, or where there was a subsequent
23        *PRUNE or *SKIP.
25    7.  Improved instruction cache flush for POWER/PowerPC.
26        Patch by Daniel Richard G.
28    8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
29        grep:
31        (a) There is now no limit to the number of patterns to be matched.
33        (b) An error is given if a pattern is too long.
35        (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
36            are now supported.
38        (d) --exclude-from and --include-from (multiple use) have been added.
40        (e) Exclusions and inclusions now apply to all files and directories, not
41            just to those obtained from scanning a directory recursively.
43        (f) Multiple uses of -f and --file-list are now supported.
45        (g) In a Windows environment, the default for -d has been changed from
46            "read" (the GNU grep default) to "skip", because otherwise the presence
47            of a directory in the file list provokes an error.
49        (h) The documentation has been revised and clarified in places.
51    9.  Improve the matching speed of capturing brackets.
53    10. Changed the meaning of \X so that it now matches a Unicode extended
54        grapheme cluster.
56    11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
57        out POSIX threads when JIT support is configured.
59    12. Added support for PCRE_STUDY_EXTRA_NEEDED.
61    13. In the POSIX wrapper regcomp() function, setting re_nsub field in the preg
62        structure could go wrong in environments where size_t is not the same size
63        as int.
65    14. Applied user-supplied patch to pcrecpp.cc to allow PCRE_NO_UTF8_CHECK to be
66        set.
68    15. The EBCDIC support had decayed; later updates to the code had included
69        explicit references to (e.g.) \x0a instead of CHAR_LF. There has been a
70        general tidy up of EBCDIC-related issues, and the documentation was also
71        not quite right. There is now a test that can be run on ASCII systems to
72        check some of the EBCDIC-related things (but is it not a full test).
74    16. The new PCRE_STUDY_EXTRA_NEEDED option is now used by pcregrep, resulting
75        in a small tidy to the code.
77    17. Fix JIT tests when UTF is disabled and both 8 and 16 bit mode are enabled.
79    18. If the --only-matching (-o) option in pcregrep is specified multiple
80        times, each one causes appropriate output. For example, -o1 -o2 outputs the
81        substrings matched by the 1st and 2nd capturing parentheses. A separating
82        string can be specified by --om-separator (default empty).
85    Version 8.31 06-July-2012
86    -------------------------
88    1.  Fixing a wrong JIT test case and some compiler warnings.
90    2.  Removed a bashism from the RunTest script.
92    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
93        to unsigned type, result still unsigned" that was given by an MS compiler
94        on encountering the code "-sizeof(xxx)".
96    4.  Partial matching support is added to the JIT compiler.
98    5.  Fixed several bugs concerned with partial matching of items that consist
99        of more than one character:
101        (a) /^(..)\1/ did not partially match "aba" because checking references was
102            done on an "all or nothing" basis. This also applied to repeated
103            references.
105        (b) \R did not give a hard partial match if \r was found at the end of the
106            subject.
108        (c) \X did not give a hard partial match after matching one or more
109            characters at the end of the subject.
111        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
112            a partial match for the string "\r".
114        (e) When newline was set to CRLF, the metacharacter "." did not recognize
115            a partial match for a CR character at the end of the subject string.
117    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
118        running pcretest, the text "(JIT)" added to the output whenever JIT is
119        actually used to run the match.
121    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
122        or /S+[+] with a digit between 1 and 7.
124    8.  OP_NOT now supports any UTF character not just single-byte ones.
126    9.  (*MARK) control verb is now supported by the JIT compiler.
128    10. The command "./RunTest list" lists the available tests without actually
129        running any of them. (Because I keep forgetting what they all are.)
133    12. Applied a (slightly modified) user-supplied patch that improves performance
134        when the heap is used for recursion (compiled with --disable-stack-for-
135        recursion). Instead of malloc and free for each heap frame each time a
136        logical recursion happens, frames are retained on a chain and re-used where
137        possible. This sometimes gives as much as 30% improvement.
139    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
140        call.
142    14. As documented, (*COMMIT) is now confined to within a positive assertion.
144    15. It is now possible to link pcretest with libedit as an alternative to
145        libreadline.
147    16. (*COMMIT) control verb is now supported by the JIT compiler.
149    17. The Unicode data tables have been updated to Unicode 6.1.0.
151    18. Added --file-list option to pcregrep.
153    19. Added binary file support to pcregrep, including the -a, --binary-files,
154        -I, and --text options.
156    20. The madvise function is renamed for posix_madvise for QNX compatibility
157        reasons. Fixed by Giuseppe D'Angelo.
159    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
161    22. Changed the option for creating symbolic links for 16-bit man pages from
162        -s to -sf so that re-installing does not cause issues.
164    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
166    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
167        matches in certain environments (the workspace was not being correctly
168        retained). Also added to pcre_dfa_exec() a simple plausibility check on
169        some of the workspace data at the beginning of a restart.
171    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
172        was not doing so when it should - probably a typo introduced by SVN 528
173        (change 8.10/14).
175    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
176        \w+ when the character tables indicated that \x{c4} was a word character.
177        There were several related cases, all because the tests for doing a table
178        lookup were testing for characters less than 127 instead of 255.
180    27. If a pattern contains capturing parentheses that are not used in a match,
181        their slots in the ovector are set to -1. For those that are higher than
182        any matched groups, this happens at the end of processing. In the case when
183        there were back references that the ovector was too small to contain
184        (causing temporary malloc'd memory to be used during matching), and the
185        highest capturing number was not used, memory off the end of the ovector
186        was incorrectly being set to -1. (It was using the size of the temporary
187        memory instead of the true size.)
189    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
190        ovector size, it uses memory at the end of the block that it has got.
192    29. Check for an overlong MARK name and give an error at compile time. The
193        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
195    30. JIT compiler update.
197    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
198        Rill for the patch.
200    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
202    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
204    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
205        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
206        was enabled.
208    35. Improve JIT code generation for greedy plus quantifier.
210    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
211        1 to "aa" instead of to an empty string. The bug affected repeated groups
212        that could potentially match an empty string.
214    37. Optimizing single character iterators in JIT.
216    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
217        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
218        codepoints that are too big for the mode are faulted, and in a UTF mode,
219        disallowed codepoints are also faulted.
221    39. If PCRE was compiled with UTF support, in three places in the DFA
222        matcher there was code that should only have been obeyed in UTF mode, but
223        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
224        processing when bytes with values greater than 127 were present. In 16-bit
225        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
226        both cases the values are those that cannot be the first data item in a UTF
227        character. The three items that might have provoked this were recursions,
228        possessively repeated groups, and atomic groups.
230    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
231        and pcregrep, because some OS require shared objects to be explicitly
232        passed to ld, causing the link step to fail if they are not.
234    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
235        mode, patterns that started with \h* or \R* might be incorrectly matched.
238    Version 8.30 04-February-2012
239    -----------------------------
241    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
242        name is defined in ctype.h.
244    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
245        only in quite long subpatterns.
247    3.  Removed the function pcre_info(), which has been obsolete and deprecated
248        since it was replaced by pcre_fullinfo() in February 2000.
250    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
251        match a (*MARK), and the match failed at the start of the subject, a
252        reference to memory before the start of the subject could occur. This bug
253        was introduced by fix 17 of release 8.21.
255    5.  A reference to an unset group with zero minimum repetition was giving
256        totally wrong answers (in non-JavaScript-compatibility mode). For example,
257        /(another)?(\1?)test/ matched against "hello world test". This bug was
258        introduced in release 8.13.
260    6.  Add support for 16-bit character strings (a large amount of work involving
261        many changes and refactorings).
263    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
264        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
265        from a file.
267    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
268        rounding is not applied in this particular case).
270    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
271        if they appear, or are escaped, in patterns.
273    10. Get rid of a number of -Wunused-but-set-variable warnings.
275    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
276        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
277        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
278        also returns the mark "x". This bug applied to capturing parentheses,
279        non-capturing parentheses, and atomic parentheses. It also applied to some
280        assertions.
282    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
283        information out of configure.ac instead of relying on pcre.h.generic, which
284        is not stored in the repository.
286    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
287        -lreadline.
289    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
291    15. Applied Graycode's patch to put the top-level frame on the stack rather
292        than the heap when not using the stack for recursion. This gives a
293        performance improvement in many cases when recursion is not deep.
295    16. Experimental code added to "pcretest -C" to output the stack frame size.
298    Version 8.21 12-Dec-2011
299    ------------------------
301    1.  Updating the JIT compiler.
303    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
304        are added as well.
306    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
307        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
308        calling _pcre_jit_exec. Some extra comments are added.
310    4.  (*MARK) settings inside atomic groups that do not contain any capturing
311        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
312        was introduced by change 18 for 8.20.
314    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
315        ECMA-262 standard.
317    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
318        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
319        This bug was probably introduced by change 9 of 8.13.
321    7.  While fixing 6 above, I noticed that a number of other items were being
322        incorrectly rejected as "not fixed length". This arose partly because newer
323        opcodes had not been added to the fixed-length checking code. I have (a)
324        corrected the bug and added tests for these items, and (b) arranged for an
325        error to occur if an unknown opcode is encountered while checking for fixed
326        length instead of just assuming "not fixed length". The items that were
327        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
328        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
329        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
331    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
332        being incorrectly compiled and would have given unpredicatble results.
334    9.  A possessively repeated subpattern with minimum repeat count greater than
335        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
336        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
337        the first (A) could occur when it should not.
339    10. Add a cast and remove a redundant test from the code.
341    11. JIT should use pcre_malloc/pcre_free for allocation.
343    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
344        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
345        is anything other than /usr, -L is still shown).
347    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
349    14. Perl does not support \N without a following name in a [] class; PCRE now
350        also gives an error.
352    15. If a forward reference was repeated with an upper limit of around 2000,
353        it caused the error "internal error: overran compiling workspace". The
354        maximum number of forward references (including repeats) was limited by the
355        internal workspace, and dependent on the LINK_SIZE. The code has been
356        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
357        the default depends on LINK_SIZE. There is a new upper limit (for safety)
358        of around 200,000 forward references. While doing this, I also speeded up
359        the filling in of repeated forward references.
361    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
362        incorrectly expecting the subject to contain another "a" after the start.
364    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
365        in the match, the SKIP should be ignored. This was not happening; instead
366        the SKIP was being treated as NOMATCH. For patterns such as
367        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
368        tested.
370    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
371        now much more compatible with Perl, in particular in cases where the result
372        is a non-match for a non-anchored pattern. For example, if
373        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
374        "m", where previously it did not return a name. A side effect of this
375        change is that for partial matches, the last encountered mark name is
376        returned, as for non matches. A number of tests that were previously not
377        Perl-compatible have been moved into the Perl-compatible test files. The
378        refactoring has had the pleasing side effect of removing one argument from
379        the match() function, thus reducing its stack requirements.
381    19. If the /S+ option was used in pcretest to study a pattern using JIT,
382        subsequent uses of /S (without +) incorrectly behaved like /S+.
384    21. Retrieve executable code size support for the JIT compiler and fixing
385        some warnings.
387    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
388        not work when the shorter character appeared right at the end of the
389        subject string.
391    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
392        systems.
394    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
395        output it when the /M option is used in pcretest.
397    25. The CheckMan script was not being included in the distribution. Also, added
398        an explicit "perl" to run Perl scripts from the PrepareRelease script
399        because this is reportedly needed in Windows.
401    26. If study data was being save in a file and studying had not found a set of
402        "starts with" bytes for the pattern, the data written to the file (though
403        never used) was taken from uninitialized memory and so caused valgrind to
404        complain.
406    27. Updated RunTest.bat as provided by Sheri Pierce.
408    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
410    29. Computation of memory usage for the table of capturing group names was
411        giving an unnecessarily large value.
414    Version 8.20 21-Oct-2011
415    ------------------------
417    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
418        a POSIX class. After further experiments with Perl, which convinced me that
419        Perl has bugs and confusions, a closing square bracket is no longer allowed
420        in a POSIX name. This bug also affected patterns with classes that started
421        with full stops.
423    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
424        captured substring, but while checking the failing first alternative,
425        substring 1 is temporarily captured. If the output vector supplied to
426        pcre_exec() was not big enough for this capture, the yield of the function
427        was still zero ("insufficient space for captured substrings"). This cannot
428        be totally fixed without adding another stack variable, which seems a lot
429        of expense for a edge case. However, I have improved the situation in cases
430        such as /(a)(b)x|abc/ matched against "abc", where the return code
431        indicates that fewer than the maximum number of slots in the ovector have
432        been set.
434    3.  Related to (2) above: when there are more back references in a pattern than
435        slots in the output vector, pcre_exec() uses temporary memory during
436        matching, and copies in the captures as far as possible afterwards. It was
437        using the entire output vector, but this conflicts with the specification
438        that only 2/3 is used for passing back captured substrings. Now it uses
439        only the first 2/3, for compatibility. This is, of course, another edge
440        case.
442    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
443        main code base, and can be used by building with --enable-jit. When this is
444        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
445        runtime --no-jit option is given.
447    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
448        ovector, the return from the function was zero, implying that there were
449        other matches that did not fit. The correct "exactly full" value is now
450        returned.
452    6.  If a subpattern that was called recursively or as a subroutine contained
453        (*PRUNE) or any other control that caused it to give a non-standard return,
454        invalid errors such as "Error -26 (nested recursion at the same subject
455        position)" or even infinite loops could occur.
457    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
458        computing the minimum length on reaching *ACCEPT, and so ended up with the
459        wrong value of 1 rather than 0. Further investigation indicates that
460        computing a minimum subject length in the presence of *ACCEPT is difficult
461        (think back references, subroutine calls), and so I have changed the code
462        so that no minimum is registered for a pattern that contains *ACCEPT.
464    8.  If (*THEN) was present in the first (true) branch of a conditional group,
465        it was not handled as intended. [But see 16 below.]
467    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
468        Sheri Pierce.
470    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
471        the first byte in a match must be "a".
473    11. Change 17 for 8.13 increased the recursion depth for patterns like
474        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
475        pattern contains any instances of (*THEN). If it does not, the old
476        optimizations are restored. It would be nice to do this on a per-group
477        basis, but at the moment that is not feasible.
479    12. In some environments, the output of pcretest -C is CRLF terminated. This
480        broke RunTest's code that checks for the link size. A single white space
481        character after the value is now allowed for.
483    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
484        For "fr", it uses the Windows-specific input and output files.
486    14. If (*THEN) appeared in a group that was called recursively or as a
487        subroutine, it did not work as intended. [But see next item.]
489    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
490        pattern fragments (but not containing any | characters). If A and B are
491        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
492        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
493        D. In other words, Perl considers parentheses that do not contain any |
494        characters to be part of a surrounding alternative, whereas PCRE was
495        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
496        differently. PCRE now behaves in the same way as Perl, except in the case
497        of subroutine/recursion calls such as (?1) which have in any case always
498        been different (but PCRE had them first :-).
500    16. Related to 15 above: Perl does not treat the | in a conditional group as
501        creating alternatives. Such a group is treated in the same way as an
502        ordinary group without any | characters when processing (*THEN). PCRE has
503        been changed to match Perl's behaviour.
505    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
506        RunGrepTest script failed.
508    18. Change 22 for version 13 caused atomic groups to use more stack. This is
509        inevitable for groups that contain captures, but it can lead to a lot of
510        stack use in large patterns. The old behaviour has been restored for atomic
511        groups that do not contain any capturing parentheses.
513    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
514        suppress the check for a minimum subject length at run time. (If it was
515        given to pcre_exec() or pcre_dfa_exec() it did work.)
517    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
518        fail to work when decoding hex characters in data strings in EBCDIC
519        environments.
521    21. It appears that in at least one Mac OS environment, the isxdigit() function
522        is implemented as a macro that evaluates to its argument more than once,
523        contravening the C 90 Standard (I haven't checked a later standard). There
524        was an instance in pcretest which caused it to go wrong when processing
525        \x{...} escapes in subject strings. The has been rewritten to avoid using
526        things like p++ in the argument of isxdigit().
529    Version 8.13 16-Aug-2011
530    ------------------------
532    1.  The Unicode data tables have been updated to Unicode 6.0.0.
534    2.  Two minor typos in pcre_internal.h have been fixed.
536    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
537        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
538        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
540    4.  There were a number of related bugs in the code for matching backrefences
541        caselessly in UTF-8 mode when codes for the characters concerned were
542        different numbers of bytes. For example, U+023A and U+2C65 are an upper
543        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
544        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
545        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
546        2-byte code at the end of the subject (it thought there wasn't enough data
547        left).
549    5.  Comprehensive information about what went wrong is now returned by
550        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
551        as the output vector has at least 2 elements. The offset of the start of
552        the failing character and a reason code are placed in the vector.
554    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
555        now returned is for the first byte of the failing character, instead of the
556        last byte inspected. This is an incompatible change, but I hope it is small
557        enough not to be a problem. It makes the returned offset consistent with
558        pcre_exec() and pcre_dfa_exec().
560    7.  pcretest now gives a text phrase as well as the error number when
561        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
562        failure, the offset and reason code are output.
564    8.  When \R was used with a maximizing quantifier it failed to skip backwards
565        over a \r\n pair if the subsequent match failed. Instead, it just skipped
566        back over a single character (\n). This seems wrong (because it treated the
567        two characters as a single entity when going forwards), conflicts with the
568        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
569        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
570        has been changed.
572    9.  Some internal refactoring has changed the processing so that the handling
573        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
574        time (the PCRE_DOTALL option was changed this way some time ago: version
575        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
576        which was always a bit of a fudge. It also means that there is one less
577        argument for the match() function, which reduces its stack requirements
578        slightly. This change also fixes an incompatibility with Perl: the pattern
579        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
581    10. More internal refactoring has drastically reduced the number of recursive
582        calls to match() for possessively repeated groups such as (abc)++ when
583        using pcre_exec().
585    11. While implementing 10, a number of bugs in the handling of groups were
586        discovered and fixed:
588        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
589        (a|)*(?1) gave a compile-time internal error.
590        ((a|)+)+  did not notice that the outer group could match an empty string.
591        (^a|^)+   was not marked as anchored.
592        (.*a|.*)+ was not marked as matching at start or after a newline.
594    12. Yet more internal refactoring has removed another argument from the match()
595        function. Special calls to this function are now indicated by setting a
596        value in a variable in the "match data" data block.
598    13. Be more explicit in pcre_study() instead of relying on "default" for
599        opcodes that mean there is no starting character; this means that when new
600        ones are added and accidentally left out of pcre_study(), testing should
601        pick them up.
603    14. The -s option of pcretest has been documented for ages as being an old
604        synonym of -m (show memory usage). I have changed it to mean "force study
605        for every regex", that is, assume /S for every regex. This is similar to -i
606        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
607        using it. It makes it easier to run collections of tests with and without
608        study enabled, and thereby test pcre_study() more easily. All the standard
609        tests are now run with and without -s (but some patterns can be marked as
610        "never study" - see 20 below).
612    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
613        restoration of the capturing data to the outer values was not happening
614        correctly.
616    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
617        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
618        pattern had matched an empty string, and so incorrectly returned a no
619        match.
621    17. There was optimizing code for the last branch of non-capturing parentheses,
622        and also for the obeyed branch of a conditional subexpression, which used
623        tail recursion to cut down on stack usage. Unfortunately, now that there is
624        the possibility of (*THEN) occurring in these branches, tail recursion is
625        no longer possible because the return has to be checked for (*THEN). These
626        two optimizations have therefore been removed. [But see 8.20/11 above.]
628    18. If a pattern containing \R was studied, it was assumed that \R always
629        matched two bytes, thus causing the minimum subject length to be
630        incorrectly computed because \R can also match just one byte.
632    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
633        was incorrectly computed.
635    20. If /S is present twice on a test pattern in pcretest input, it now
636        *disables* studying, thereby overriding the use of -s on the command line
637        (see 14 above). This is necessary for one or two tests to keep the output
638        identical in both cases.
640    21. When (*ACCEPT) was used in an assertion that matched an empty string and
641        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
643    22. When an atomic group that contained a capturing parenthesis was
644        successfully matched, but the branch in which it appeared failed, the
645        capturing was not being forgotten if a higher numbered group was later
646        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
647        group 1 to "a", when in fact it should be unset. This applied to multi-
648        branched capturing and non-capturing groups, repeated or not, and also to
649        positive assertions (capturing in negative assertions does not happen
650        in PCRE) and also to nested atomic groups.
652    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
653        subject after a captured substring, to make it easier to tell which of a
654        number of identical substrings has been captured.
656    24. The way atomic groups are processed by pcre_exec() has been changed so that
657        if they are repeated, backtracking one repetition now resets captured
658        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
659        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
660        "aaa". Previously, it would have been "a". As part of this code
661        refactoring, the way recursive calls are handled has also been changed.
663    25. If an assertion condition captured any substrings, they were not passed
664        back unless some other capturing happened later. For example, if
665        (?(?=(a))a) was matched against "a", no capturing was returned.
667    26. When studying a pattern that contained subroutine calls or assertions,
668        the code for finding the minimum length of a possible match was handling
669        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
670        group 1 called group 2 while simultaneously a separate group 2 called group
671        1). A stack overflow occurred in this case. I have fixed this by limiting
672        the recursion depth to 10.
674    27. Updated RunTest.bat in the distribution to the version supplied by Tom
675        Fortmann. This supports explicit test numbers on the command line, and has
676        argument validation and error reporting.
678    28. An instance of \X with an unlimited repeat could fail if at any point the
679        first character it looked at was a mark character.
681    29. Some minor code refactoring concerning Unicode properties and scripts
682        should reduce the stack requirement of match() slightly.
684    30. Added the '=' option to pcretest to check the setting of unused capturing
685        slots at the end of the pattern, which are documented as being -1, but are
686        not included in the return count.
688    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
689        compiled something random. Now it gives a compile-time error (as does
690        Perl).
692    32. A *MARK encountered during the processing of a positive assertion is now
693        recorded and passed back (compatible with Perl).
695    33. If --only-matching or --colour was set on a pcregrep call whose pattern
696        had alternative anchored branches, the search for a second match in a line
697        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
698        matched the line "0102" twice. The same bug affected patterns that started
699        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
700        twice.
702    34. Previously, PCRE did not allow quantification of assertions. However, Perl
703        does, and because of capturing effects, quantifying parenthesized
704        assertions may at times be useful. Quantifiers are now allowed for
705        parenthesized assertions.
707    35. A minor code tidy in pcre_compile() when checking options for \R usage.
709    36. \g was being checked for fancy things in a character class, when it should
710        just be a literal "g".
712    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
713        appearance of a nested POSIX class supersedes an apparent external class.
714        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
715        unescaped square brackets may also appear as part of class names. For
716        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
717        more like Perl. (But see 8.20/1 above.)
719    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
720        was because it thought it was \N{name}, which is not supported).
722    39. Add minix to OS list not supporting the -S option in pcretest.
724    40. PCRE tries to detect cases of infinite recursion at compile time, but it
725        cannot analyze patterns in sufficient detail to catch mutual recursions
726        such as ((?1))((?2)). There is now a runtime test that gives an error if a
727        subgroup is called recursively as a subpattern for a second time at the
728        same position in the subject string. In previous releases this might have
729        been caught by the recursion limit, or it might have run out of stack.
731    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
732        happen only once. PCRE was, however incorrectly giving a compile time error
733        "recursive call could loop indefinitely" because it cannot analyze the
734        pattern in sufficient detail. The compile time test no longer happens when
735        PCRE is compiling a conditional subpattern, but actual runaway loops are
736        now caught at runtime (see 40 above).
738    42. It seems that Perl allows any characters other than a closing parenthesis
739        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
740        has been changed to be the same.
742    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
743        as not to get warnings when autogen.sh is called. Also changed
744        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
746    44. To help people who use pcregrep to scan files containing exceedingly long
747        lines, the following changes have been made:
749        (a) The default value of the buffer size parameter has been increased from
750            8K to 20K. (The actual buffer used is three times this size.)
752        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
753            PCRE is built.
755        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
756            to be set at run time.
758        (d) Numerical values in pcregrep options can be followed by K or M, for
759            example --buffer-size=50K.
761        (e) If a line being scanned overflows pcregrep's buffer, an error is now
762            given and the return code is set to 2.
764    45. Add a pointer to the latest mark to the callout data block.
766    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
767        partial match of an empty string instead of no match. This was specific to
768        the use of ".".
770    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
771        complete match instead of a partial match. This bug was dependent on both
772        the PCRE_UTF8 and PCRE_DOTALL options being set.
774    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
775        starting byte set, because \b was not being ignored.
778    Version 8.12 15-Jan-2011
779    ------------------------
781    1.  Fixed some typos in the markup of the man pages, and wrote a script that
782        checks for such things as part of the documentation building process.
784    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
785        --match-limit and --recursion-limit options (added for 8.11). In
786        particular, this made one of the standard tests fail. (The integer value
787        went into the wrong half of a long int.)
789    3.  If the --colour option was given to pcregrep with -v (invert match), it
790        did strange things, either producing crazy output, or crashing. It should,
791        of course, ignore a request for colour when reporting lines that do not
792        match.
794    4.  Another pcregrep bug caused similar problems if --colour was specified with
795        -M (multiline) and the pattern match finished with a line ending.
797    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
798        matched in multiline mode, the following line was shown as part of the
799        match. This seems wrong, so I have changed it.
801    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
802        the check for further matches in the same line (so they could be coloured)
803        to overrun the end of the current line. If another match was found, it was
804        incorrectly shown (and then shown again when found in the next line).
806    7.  If pcregrep was compiled under Windows, there was a reference to the
807        function pcregrep_exit() before it was defined. I am assuming this was
808        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
809        reported by a user. I've moved the definition above the reference.
812    Version 8.11 10-Dec-2010
813    ------------------------
815    1.  (*THEN) was not working properly if there were untried alternatives prior
816        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
817        backtracked to try for "b" instead of moving to the next alternative branch
818        at the same level (in this case, to look for "c"). The Perl documentation
819        is clear that when (*THEN) is backtracked onto, it goes to the "next
820        alternative in the innermost enclosing group".
822    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
823        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
824        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
825        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
826        (*THEN).
828    3.  If \s appeared in a character class, it removed the VT character from
829        the class, even if it had been included by some previous item, for example
830        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
831        of \s, but is part of the POSIX "space" class.)
833    4.  A partial match never returns an empty string (because you can always
834        match an empty string at the end of the subject); however the checking for
835        an empty string was starting at the "start of match" point. This has been
836        changed to the "earliest inspected character" point, because the returned
837        data for a partial match starts at this character. This means that, for
838        example, /(?<=abc)def/ gives a partial match for the subject "abc"
839        (previously it gave "no match").
841    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
842        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
843        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
844        has an implication that the given string is incomplete (because a partial
845        match is preferred over a full match). For this reason, these items now
846        give a partial match in this situation. [Aside: previously, the one case
847        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
848        match rather than a full match, which was wrong by the old rules, but is
849        now correct.]
851    6.  There was a bug in the handling of #-introduced comments, recognized when
852        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
853        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
854        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
855        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
856        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
857        places in pcre_compile().
859    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
860        comments when looking ahead for named forward references to subpatterns,
861        the only newline sequence it recognized was NL. It now handles newlines
862        according to the set newline convention.
864    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
865        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
866        cater for a lack of strerror(). These oversights have been fixed.
868    9.  Added --match-limit and --recursion-limit to pcregrep.
870    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
872    11. When the -o option was used, pcregrep was setting a return code of 1, even
873        when matches were found, and --line-buffered was not being honoured.
875    12. Added an optional parentheses number to the -o and --only-matching options
876        of pcregrep.
878    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
879        can match an empty string. The code to do it in pcretest and pcredemo
880        needed fixing:
882        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
883            only one byte after an empty string match just before CRLF (this case
884            just got forgotten; "any" and "anycrlf" were OK).
886        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
887            mode when an empty string match preceded an ASCII character followed by
888            a non-ASCII character. (The code for advancing by one character rather
889            than one byte was nonsense.)
891        (c) The pcredemo.c sample program did not have any code at all to handle
892            the cases when CRLF is a valid newline sequence.
894    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
895        as a starting offset was within the subject string. There is now a new
896        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
897        negative or greater than the length of the string. In order to test this,
898        pcretest is extended to allow the setting of negative starting offsets.
900    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
901        starting offset points to the beginning of a UTF-8 character was
902        unnecessarily clumsy. I tidied it up.
904    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
905        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
907    17. Nobody had reported that the --include_dir option, which was added in
908        release 7.7 should have been called --include-dir (hyphen, not underscore)
909        for compatibility with GNU grep. I have changed it to --include-dir, but
910        left --include_dir as an undocumented synonym, and the same for
911        --exclude-dir, though that is not available in GNU grep, at least as of
912        release 2.5.4.
914    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
915        characters from a string of bytes) have been redefined so as not to use
916        loops, in order to improve performance in some environments. At the same
917        time, I abstracted some of the common code into auxiliary macros to save
918        repetition (this should not affect the compiled code).
920    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
921        compile-time error is now given if \c is not followed by an ASCII
922        character, that is, a byte less than 128. (In EBCDIC mode, the code is
923        different, and any byte value is allowed.)
925    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
926        START_OPTIMIZE option, which is now allowed at compile time - but just
927        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
928        to pcregrep and other applications that have no direct access to PCRE
929        options. The new /Y option in pcretest sets this option when calling
930        pcre_compile().
932    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
933        back references. Groups containing recursive back references were forced to
934        be atomic by that change, but in the case of named groups, the amount of
935        memory required was incorrectly computed, leading to "Failed: internal
936        error: code overflow". This has been fixed.
938    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
939        pcretest.c, to avoid build problems in some Borland environments.
942    Version 8.10 25-Jun-2010
943  ------------------------  ------------------------
945  1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and  1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and

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