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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.13 30-Apr-2011  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.
52    Version 8.31 06-July-2012
53    -------------------------
55    1.  Fixing a wrong JIT test case and some compiler warnings.
57    2.  Removed a bashism from the RunTest script.
59    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
60        to unsigned type, result still unsigned" that was given by an MS compiler
61        on encountering the code "-sizeof(xxx)".
63    4.  Partial matching support is added to the JIT compiler.
65    5.  Fixed several bugs concerned with partial matching of items that consist
66        of more than one character:
68        (a) /^(..)\1/ did not partially match "aba" because checking references was
69            done on an "all or nothing" basis. This also applied to repeated
70            references.
72        (b) \R did not give a hard partial match if \r was found at the end of the
73            subject.
75        (c) \X did not give a hard partial match after matching one or more
76            characters at the end of the subject.
78        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
79            a partial match for the string "\r".
81        (e) When newline was set to CRLF, the metacharacter "." did not recognize
82            a partial match for a CR character at the end of the subject string.
84    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
85        running pcretest, the text "(JIT)" added to the output whenever JIT is
86        actually used to run the match.
88    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
89        or /S+[+] with a digit between 1 and 7.
91    8.  OP_NOT now supports any UTF character not just single-byte ones.
93    9.  (*MARK) control verb is now supported by the JIT compiler.
95    10. The command "./RunTest list" lists the available tests without actually
96        running any of them. (Because I keep forgetting what they all are.)
100    12. Applied a (slightly modified) user-supplied patch that improves performance
101        when the heap is used for recursion (compiled with --disable-stack-for-
102        recursion). Instead of malloc and free for each heap frame each time a
103        logical recursion happens, frames are retained on a chain and re-used where
104        possible. This sometimes gives as much as 30% improvement.
106    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
107        call.
109    14. As documented, (*COMMIT) is now confined to within a positive assertion.
111    15. It is now possible to link pcretest with libedit as an alternative to
112        libreadline.
114    16. (*COMMIT) control verb is now supported by the JIT compiler.
116    17. The Unicode data tables have been updated to Unicode 6.1.0.
118    18. Added --file-list option to pcregrep.
120    19. Added binary file support to pcregrep, including the -a, --binary-files,
121        -I, and --text options.
123    20. The madvise function is renamed for posix_madvise for QNX compatibility
124        reasons. Fixed by Giuseppe D'Angelo.
126    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
128    22. Changed the option for creating symbolic links for 16-bit man pages from
129        -s to -sf so that re-installing does not cause issues.
131    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
133    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
134        matches in certain environments (the workspace was not being correctly
135        retained). Also added to pcre_dfa_exec() a simple plausibility check on
136        some of the workspace data at the beginning of a restart.
138    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
139        was not doing so when it should - probably a typo introduced by SVN 528
140        (change 8.10/14).
142    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
143        \w+ when the character tables indicated that \x{c4} was a word character.
144        There were several related cases, all because the tests for doing a table
145        lookup were testing for characters less than 127 instead of 255.
147    27. If a pattern contains capturing parentheses that are not used in a match,
148        their slots in the ovector are set to -1. For those that are higher than
149        any matched groups, this happens at the end of processing. In the case when
150        there were back references that the ovector was too small to contain
151        (causing temporary malloc'd memory to be used during matching), and the
152        highest capturing number was not used, memory off the end of the ovector
153        was incorrectly being set to -1. (It was using the size of the temporary
154        memory instead of the true size.)
156    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
157        ovector size, it uses memory at the end of the block that it has got.
159    29. Check for an overlong MARK name and give an error at compile time. The
160        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
162    30. JIT compiler update.
164    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
165        Rill for the patch.
167    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
169    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
171    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
172        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
173        was enabled.
175    35. Improve JIT code generation for greedy plus quantifier.
177    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
178        1 to "aa" instead of to an empty string. The bug affected repeated groups
179        that could potentially match an empty string.
181    37. Optimizing single character iterators in JIT.
183    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
184        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
185        codepoints that are too big for the mode are faulted, and in a UTF mode,
186        disallowed codepoints are also faulted.
188    39. If PCRE was compiled with UTF support, in three places in the DFA
189        matcher there was code that should only have been obeyed in UTF mode, but
190        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
191        processing when bytes with values greater than 127 were present. In 16-bit
192        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
193        both cases the values are those that cannot be the first data item in a UTF
194        character. The three items that might have provoked this were recursions,
195        possessively repeated groups, and atomic groups.
197    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
198        and pcregrep, because some OS require shared objects to be explicitly
199        passed to ld, causing the link step to fail if they are not.
201    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
202        mode, patterns that started with \h* or \R* might be incorrectly matched.
205    Version 8.30 04-February-2012
206    -----------------------------
208    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
209        name is defined in ctype.h.
211    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
212        only in quite long subpatterns.
214    3.  Removed the function pcre_info(), which has been obsolete and deprecated
215        since it was replaced by pcre_fullinfo() in February 2000.
217    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
218        match a (*MARK), and the match failed at the start of the subject, a
219        reference to memory before the start of the subject could occur. This bug
220        was introduced by fix 17 of release 8.21.
222    5.  A reference to an unset group with zero minimum repetition was giving
223        totally wrong answers (in non-JavaScript-compatibility mode). For example,
224        /(another)?(\1?)test/ matched against "hello world test". This bug was
225        introduced in release 8.13.
227    6.  Add support for 16-bit character strings (a large amount of work involving
228        many changes and refactorings).
230    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
231        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
232        from a file.
234    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
235        rounding is not applied in this particular case).
237    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
238        if they appear, or are escaped, in patterns.
240    10. Get rid of a number of -Wunused-but-set-variable warnings.
242    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
243        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
244        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
245        also returns the mark "x". This bug applied to capturing parentheses,
246        non-capturing parentheses, and atomic parentheses. It also applied to some
247        assertions.
249    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
250        information out of configure.ac instead of relying on pcre.h.generic, which
251        is not stored in the repository.
253    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
254        -lreadline.
256    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
258    15. Applied Graycode's patch to put the top-level frame on the stack rather
259        than the heap when not using the stack for recursion. This gives a
260        performance improvement in many cases when recursion is not deep.
262    16. Experimental code added to "pcretest -C" to output the stack frame size.
265    Version 8.21 12-Dec-2011
266    ------------------------
268    1.  Updating the JIT compiler.
270    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
271        are added as well.
273    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
274        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
275        calling _pcre_jit_exec. Some extra comments are added.
277    4.  (*MARK) settings inside atomic groups that do not contain any capturing
278        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
279        was introduced by change 18 for 8.20.
281    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
282        ECMA-262 standard.
284    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
285        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
286        This bug was probably introduced by change 9 of 8.13.
288    7.  While fixing 6 above, I noticed that a number of other items were being
289        incorrectly rejected as "not fixed length". This arose partly because newer
290        opcodes had not been added to the fixed-length checking code. I have (a)
291        corrected the bug and added tests for these items, and (b) arranged for an
292        error to occur if an unknown opcode is encountered while checking for fixed
293        length instead of just assuming "not fixed length". The items that were
294        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
295        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
296        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
298    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
299        being incorrectly compiled and would have given unpredicatble results.
301    9.  A possessively repeated subpattern with minimum repeat count greater than
302        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
303        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
304        the first (A) could occur when it should not.
306    10. Add a cast and remove a redundant test from the code.
308    11. JIT should use pcre_malloc/pcre_free for allocation.
310    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
311        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
312        is anything other than /usr, -L is still shown).
314    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
316    14. Perl does not support \N without a following name in a [] class; PCRE now
317        also gives an error.
319    15. If a forward reference was repeated with an upper limit of around 2000,
320        it caused the error "internal error: overran compiling workspace". The
321        maximum number of forward references (including repeats) was limited by the
322        internal workspace, and dependent on the LINK_SIZE. The code has been
323        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
324        the default depends on LINK_SIZE. There is a new upper limit (for safety)
325        of around 200,000 forward references. While doing this, I also speeded up
326        the filling in of repeated forward references.
328    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
329        incorrectly expecting the subject to contain another "a" after the start.
331    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
332        in the match, the SKIP should be ignored. This was not happening; instead
333        the SKIP was being treated as NOMATCH. For patterns such as
334        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
335        tested.
337    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
338        now much more compatible with Perl, in particular in cases where the result
339        is a non-match for a non-anchored pattern. For example, if
340        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
341        "m", where previously it did not return a name. A side effect of this
342        change is that for partial matches, the last encountered mark name is
343        returned, as for non matches. A number of tests that were previously not
344        Perl-compatible have been moved into the Perl-compatible test files. The
345        refactoring has had the pleasing side effect of removing one argument from
346        the match() function, thus reducing its stack requirements.
348    19. If the /S+ option was used in pcretest to study a pattern using JIT,
349        subsequent uses of /S (without +) incorrectly behaved like /S+.
351    21. Retrieve executable code size support for the JIT compiler and fixing
352        some warnings.
354    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
355        not work when the shorter character appeared right at the end of the
356        subject string.
358    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
359        systems.
361    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
362        output it when the /M option is used in pcretest.
364    25. The CheckMan script was not being included in the distribution. Also, added
365        an explicit "perl" to run Perl scripts from the PrepareRelease script
366        because this is reportedly needed in Windows.
368    26. If study data was being save in a file and studying had not found a set of
369        "starts with" bytes for the pattern, the data written to the file (though
370        never used) was taken from uninitialized memory and so caused valgrind to
371        complain.
373    27. Updated RunTest.bat as provided by Sheri Pierce.
375    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
377    29. Computation of memory usage for the table of capturing group names was
378        giving an unnecessarily large value.
381    Version 8.20 21-Oct-2011
382    ------------------------
384    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
385        a POSIX class. After further experiments with Perl, which convinced me that
386        Perl has bugs and confusions, a closing square bracket is no longer allowed
387        in a POSIX name. This bug also affected patterns with classes that started
388        with full stops.
390    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
391        captured substring, but while checking the failing first alternative,
392        substring 1 is temporarily captured. If the output vector supplied to
393        pcre_exec() was not big enough for this capture, the yield of the function
394        was still zero ("insufficient space for captured substrings"). This cannot
395        be totally fixed without adding another stack variable, which seems a lot
396        of expense for a edge case. However, I have improved the situation in cases
397        such as /(a)(b)x|abc/ matched against "abc", where the return code
398        indicates that fewer than the maximum number of slots in the ovector have
399        been set.
401    3.  Related to (2) above: when there are more back references in a pattern than
402        slots in the output vector, pcre_exec() uses temporary memory during
403        matching, and copies in the captures as far as possible afterwards. It was
404        using the entire output vector, but this conflicts with the specification
405        that only 2/3 is used for passing back captured substrings. Now it uses
406        only the first 2/3, for compatibility. This is, of course, another edge
407        case.
409    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
410        main code base, and can be used by building with --enable-jit. When this is
411        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
412        runtime --no-jit option is given.
414    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
415        ovector, the return from the function was zero, implying that there were
416        other matches that did not fit. The correct "exactly full" value is now
417        returned.
419    6.  If a subpattern that was called recursively or as a subroutine contained
420        (*PRUNE) or any other control that caused it to give a non-standard return,
421        invalid errors such as "Error -26 (nested recursion at the same subject
422        position)" or even infinite loops could occur.
424    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
425        computing the minimum length on reaching *ACCEPT, and so ended up with the
426        wrong value of 1 rather than 0. Further investigation indicates that
427        computing a minimum subject length in the presence of *ACCEPT is difficult
428        (think back references, subroutine calls), and so I have changed the code
429        so that no minimum is registered for a pattern that contains *ACCEPT.
431    8.  If (*THEN) was present in the first (true) branch of a conditional group,
432        it was not handled as intended. [But see 16 below.]
434    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
435        Sheri Pierce.
437    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
438        the first byte in a match must be "a".
440    11. Change 17 for 8.13 increased the recursion depth for patterns like
441        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
442        pattern contains any instances of (*THEN). If it does not, the old
443        optimizations are restored. It would be nice to do this on a per-group
444        basis, but at the moment that is not feasible.
446    12. In some environments, the output of pcretest -C is CRLF terminated. This
447        broke RunTest's code that checks for the link size. A single white space
448        character after the value is now allowed for.
450    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
451        For "fr", it uses the Windows-specific input and output files.
453    14. If (*THEN) appeared in a group that was called recursively or as a
454        subroutine, it did not work as intended. [But see next item.]
456    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
457        pattern fragments (but not containing any | characters). If A and B are
458        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
459        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
460        D. In other words, Perl considers parentheses that do not contain any |
461        characters to be part of a surrounding alternative, whereas PCRE was
462        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
463        differently. PCRE now behaves in the same way as Perl, except in the case
464        of subroutine/recursion calls such as (?1) which have in any case always
465        been different (but PCRE had them first :-).
467    16. Related to 15 above: Perl does not treat the | in a conditional group as
468        creating alternatives. Such a group is treated in the same way as an
469        ordinary group without any | characters when processing (*THEN). PCRE has
470        been changed to match Perl's behaviour.
472    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
473        RunGrepTest script failed.
475    18. Change 22 for version 13 caused atomic groups to use more stack. This is
476        inevitable for groups that contain captures, but it can lead to a lot of
477        stack use in large patterns. The old behaviour has been restored for atomic
478        groups that do not contain any capturing parentheses.
480    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
481        suppress the check for a minimum subject length at run time. (If it was
482        given to pcre_exec() or pcre_dfa_exec() it did work.)
484    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
485        fail to work when decoding hex characters in data strings in EBCDIC
486        environments.
488    21. It appears that in at least one Mac OS environment, the isxdigit() function
489        is implemented as a macro that evaluates to its argument more than once,
490        contravening the C 90 Standard (I haven't checked a later standard). There
491        was an instance in pcretest which caused it to go wrong when processing
492        \x{...} escapes in subject strings. The has been rewritten to avoid using
493        things like p++ in the argument of isxdigit().
496    Version 8.13 16-Aug-2011
497  ------------------------  ------------------------
499  1.  The Unicode data tables have been updated to Unicode 6.0.0.  1.  The Unicode data tables have been updated to Unicode 6.0.0.
# Line 20  Version 8.13 30-Apr-2011 Line 512  Version 8.13 30-Apr-2011
512      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
513      2-byte code at the end of the subject (it thought there wasn't enough data      2-byte code at the end of the subject (it thought there wasn't enough data
514      left).      left).
516  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
517      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
518      as the output vector has at least 2 elements. The offset of the start of      as the output vector has at least 2 elements. The offset of the start of
519      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
521  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
522      now returned is for the first byte of the failing character, instead of the      now returned is for the first byte of the failing character, instead of the
523      last byte inspected. This is an incompatible change, but I hope it is small      last byte inspected. This is an incompatible change, but I hope it is small
524      enough not to be a problem. It makes the returned offset consistent with      enough not to be a problem. It makes the returned offset consistent with
525      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
527  7.  pcretest now gives a text phrase as well as the error number when  7.  pcretest now gives a text phrase as well as the error number when
528      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
529      failure, the offset and reason code are output.      failure, the offset and reason code are output.
531  8.  When \R was used with a maximizing quantifier it failed to skip backwards  8.  When \R was used with a maximizing quantifier it failed to skip backwards
532      over a \r\n pair if the subsequent match failed. Instead, it just skipped      over a \r\n pair if the subsequent match failed. Instead, it just skipped
533      back over a single character (\n). This seems wrong (because it treated the      back over a single character (\n). This seems wrong (because it treated the
534      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
535      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
536      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
537      has been changed.      has been changed.
539    9.  Some internal refactoring has changed the processing so that the handling
540        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
541        time (the PCRE_DOTALL option was changed this way some time ago: version
542        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
543        which was always a bit of a fudge. It also means that there is one less
544        argument for the match() function, which reduces its stack requirements
545        slightly. This change also fixes an incompatibility with Perl: the pattern
546        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
548    10. More internal refactoring has drastically reduced the number of recursive
549        calls to match() for possessively repeated groups such as (abc)++ when
550        using pcre_exec().
552    11. While implementing 10, a number of bugs in the handling of groups were
553        discovered and fixed:
555        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
556        (a|)*(?1) gave a compile-time internal error.
557        ((a|)+)+  did not notice that the outer group could match an empty string.
558        (^a|^)+   was not marked as anchored.
559        (.*a|.*)+ was not marked as matching at start or after a newline.
561    12. Yet more internal refactoring has removed another argument from the match()
562        function. Special calls to this function are now indicated by setting a
563        value in a variable in the "match data" data block.
565    13. Be more explicit in pcre_study() instead of relying on "default" for
566        opcodes that mean there is no starting character; this means that when new
567        ones are added and accidentally left out of pcre_study(), testing should
568        pick them up.
570    14. The -s option of pcretest has been documented for ages as being an old
571        synonym of -m (show memory usage). I have changed it to mean "force study
572        for every regex", that is, assume /S for every regex. This is similar to -i
573        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
574        using it. It makes it easier to run collections of tests with and without
575        study enabled, and thereby test pcre_study() more easily. All the standard
576        tests are now run with and without -s (but some patterns can be marked as
577        "never study" - see 20 below).
579    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
580        restoration of the capturing data to the outer values was not happening
581        correctly.
583    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
584        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
585        pattern had matched an empty string, and so incorrectly returned a no
586        match.
588    17. There was optimizing code for the last branch of non-capturing parentheses,
589        and also for the obeyed branch of a conditional subexpression, which used
590        tail recursion to cut down on stack usage. Unfortunately, now that there is
591        the possibility of (*THEN) occurring in these branches, tail recursion is
592        no longer possible because the return has to be checked for (*THEN). These
593        two optimizations have therefore been removed. [But see 8.20/11 above.]
595    18. If a pattern containing \R was studied, it was assumed that \R always
596        matched two bytes, thus causing the minimum subject length to be
597        incorrectly computed because \R can also match just one byte.
599    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
600        was incorrectly computed.
602    20. If /S is present twice on a test pattern in pcretest input, it now
603        *disables* studying, thereby overriding the use of -s on the command line
604        (see 14 above). This is necessary for one or two tests to keep the output
605        identical in both cases.
607    21. When (*ACCEPT) was used in an assertion that matched an empty string and
608        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
610    22. When an atomic group that contained a capturing parenthesis was
611        successfully matched, but the branch in which it appeared failed, the
612        capturing was not being forgotten if a higher numbered group was later
613        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
614        group 1 to "a", when in fact it should be unset. This applied to multi-
615        branched capturing and non-capturing groups, repeated or not, and also to
616        positive assertions (capturing in negative assertions does not happen
617        in PCRE) and also to nested atomic groups.
619    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
620        subject after a captured substring, to make it easier to tell which of a
621        number of identical substrings has been captured.
623    24. The way atomic groups are processed by pcre_exec() has been changed so that
624        if they are repeated, backtracking one repetition now resets captured
625        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
626        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
627        "aaa". Previously, it would have been "a". As part of this code
628        refactoring, the way recursive calls are handled has also been changed.
630    25. If an assertion condition captured any substrings, they were not passed
631        back unless some other capturing happened later. For example, if
632        (?(?=(a))a) was matched against "a", no capturing was returned.
634    26. When studying a pattern that contained subroutine calls or assertions,
635        the code for finding the minimum length of a possible match was handling
636        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
637        group 1 called group 2 while simultaneously a separate group 2 called group
638        1). A stack overflow occurred in this case. I have fixed this by limiting
639        the recursion depth to 10.
641    27. Updated RunTest.bat in the distribution to the version supplied by Tom
642        Fortmann. This supports explicit test numbers on the command line, and has
643        argument validation and error reporting.
645    28. An instance of \X with an unlimited repeat could fail if at any point the
646        first character it looked at was a mark character.
648    29. Some minor code refactoring concerning Unicode properties and scripts
649        should reduce the stack requirement of match() slightly.
651    30. Added the '=' option to pcretest to check the setting of unused capturing
652        slots at the end of the pattern, which are documented as being -1, but are
653        not included in the return count.
655    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
656        compiled something random. Now it gives a compile-time error (as does
657        Perl).
659    32. A *MARK encountered during the processing of a positive assertion is now
660        recorded and passed back (compatible with Perl).
662    33. If --only-matching or --colour was set on a pcregrep call whose pattern
663        had alternative anchored branches, the search for a second match in a line
664        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
665        matched the line "0102" twice. The same bug affected patterns that started
666        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
667        twice.
669    34. Previously, PCRE did not allow quantification of assertions. However, Perl
670        does, and because of capturing effects, quantifying parenthesized
671        assertions may at times be useful. Quantifiers are now allowed for
672        parenthesized assertions.
674    35. A minor code tidy in pcre_compile() when checking options for \R usage.
676    36. \g was being checked for fancy things in a character class, when it should
677        just be a literal "g".
679    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
680        appearance of a nested POSIX class supersedes an apparent external class.
681        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
682        unescaped square brackets may also appear as part of class names. For
683        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
684        more like Perl. (But see 8.20/1 above.)
686    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
687        was because it thought it was \N{name}, which is not supported).
689    39. Add minix to OS list not supporting the -S option in pcretest.
691    40. PCRE tries to detect cases of infinite recursion at compile time, but it
692        cannot analyze patterns in sufficient detail to catch mutual recursions
693        such as ((?1))((?2)). There is now a runtime test that gives an error if a
694        subgroup is called recursively as a subpattern for a second time at the
695        same position in the subject string. In previous releases this might have
696        been caught by the recursion limit, or it might have run out of stack.
698    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
699        happen only once. PCRE was, however incorrectly giving a compile time error
700        "recursive call could loop indefinitely" because it cannot analyze the
701        pattern in sufficient detail. The compile time test no longer happens when
702        PCRE is compiling a conditional subpattern, but actual runaway loops are
703        now caught at runtime (see 40 above).
705    42. It seems that Perl allows any characters other than a closing parenthesis
706        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
707        has been changed to be the same.
709    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
710        as not to get warnings when autogen.sh is called. Also changed
711        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
713    44. To help people who use pcregrep to scan files containing exceedingly long
714        lines, the following changes have been made:
716        (a) The default value of the buffer size parameter has been increased from
717            8K to 20K. (The actual buffer used is three times this size.)
719        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
720            PCRE is built.
722        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
723            to be set at run time.
725        (d) Numerical values in pcregrep options can be followed by K or M, for
726            example --buffer-size=50K.
728        (e) If a line being scanned overflows pcregrep's buffer, an error is now
729            given and the return code is set to 2.
731    45. Add a pointer to the latest mark to the callout data block.
733    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
734        partial match of an empty string instead of no match. This was specific to
735        the use of ".".
737    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
738        complete match instead of a partial match. This bug was dependent on both
739        the PCRE_UTF8 and PCRE_DOTALL options being set.
741    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
742        starting byte set, because \b was not being ignored.
745  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
746  ------------------------  ------------------------

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