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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.00 ??-???-??  Version 8.33 xx-xxxx-201x
5    -------------------------
7    1.  Added 'U' to some constants that are compared to unsigned integers, to
8        avoid compiler signed/unsigned warnings. Added (int) casts to unsigned
9        variables that are added to signed variables, to ensure the result is
10        signed and can be negated.
12    2.  Applied patch by Daniel Richard G for quashing MSVC warnings to the
13        CMake config files.
15    3.  Revise the creation of config.h.generic so that all boolean macros are
16        #undefined, whereas non-boolean macros are #ifndef/#endif-ed. This makes
17        overriding via -D on the command line possible.
19    4.  Changing the definition of the variable "op" in pcre_exec.c from pcre_uchar
20        to unsigned int is reported to make a quite noticeable speed difference in
21        a specific Windows environment. Testing on Linux did also appear to show
22        some benefit (and it is clearly not harmful). Also fixed the definition of
23        Xop which should be unsigned.
25    5.  Related to (4), changing the definition of the intermediate variable cc
26        in repeated character loops from pcre_uchar to pcre_uint32 also gave speed
27        improvements.
29    6.  Fix forward search in JIT when link size is 3 or greater. Also removed some
30        unnecessary spaces.
32    7.  Adjust autogen.sh and configure.ac to lose warnings given by automake 1.12
33        and later.
35    8.  Fix two buffer over read issues in 16 and 32 bit modes. Affects JIT only.
37    9.  Optimizing fast_forward_start_bits in JIT.
39    10. Adding experimental support for callouts in JIT, and fixing some
40        issues revealed during this work. Namely:
42        (a) Unoptimized capturing brackets incorrectly reset on backtrack.
44        (b) Minimum length was not checked before the matching is started.
46    11. The value of capture_last that is passed to callouts was incorrect in some
47        cases when there was a capture on one path that was subsequently abandoned
48        after a backtrack. Also, the capture_last value is now reset after a
49        recursion, since all captures are also reset in this case.
51    12. The interpreter no longer returns the "too many substrings" error in the
52        case when an overflowing capture is in a branch that is subsequently
53        abandoned after a backtrack.
55    13. In the pathological case when an offset vector of size 2 is used, pcretest
56        now prints out the matched string after a yield of 0 or 1.
58    14. Inlining subpatterns in recursions, when certain conditions are fulfilled.
59        Only supported by the JIT compiler at the moment.
61    15. JIT compiler now supports 32 bit Macs thanks to Lawrence Velazquez.
63    16. Partial matches now set offsets[2] to the "bumpalong" value, that is, the
64        offset of the starting point of the matching process, provided the offsets
65        vector is large enough.
67    17. The \A escape now records a lookbehind value of 1, though its execution
68        does not actually inspect the previous character. This is to ensure that,
69        in partial multi-segment matching, at least one character from the old
70        segment is retained when a new segment is processed. Otherwise, if there
71        are no lookbehinds in the pattern, \A might match incorrectly at the start
72        of a new segment.
74    18. Added some #ifdef __VMS code into pcretest.c to help VMS implementations.
76    19. Redefined some pcre_uchar variables in pcre_exec.c as pcre_uint32; this
77        gives some modest performance improvement in 8-bit mode.
79    20. Added the PCRE-specific property \p{Xuc} for matching characters that can
80        be expressed in certain programming languages using Universal Character
81        Names.
83    21. Unicode validation has been updated in the light of Unicode Corrigendum #9,
84        which points out that "non characters" are not "characters that may not
85        appear in Unicode strings" but rather "characters that are reserved for
86        internal use and have only local meaning".
88    22. When a pattern was compiled with automatic callouts (PCRE_AUTO_CALLOUT) and
89        there was a conditional group that depended on an assertion, if the
90        assertion was false, the callout that immediately followed the alternation
91        in the condition was skipped when pcre_exec() was used for matching.
93    23. Allow an explicit callout to be inserted before an assertion that is the
94        condition for a conditional group, for compatibility with automatic
95        callouts, which always insert a callout at this point.
97    24. In 8.31, (*COMMIT) was confined to within a recursive subpattern. Perl also
98        confines (*SKIP) and (*PRUNE) in the same way, and this has now been done.
100    25. (*PRUNE) is now supported by the JIT compiler.
102    26. Fix infinite loop when /(?<=(*SKIP)ac)a/ is matched against aa.
104    27. Fix the case where there are two or more SKIPs with arguments that may be
105        ignored.
107    28. Experimental support of (*SKIP) backtracking verb in the JIT compiler.
110    Version 8.32 30-November-2012
111    -----------------------------
113    1.  Improved JIT compiler optimizations for first character search and single
114        character iterators.
116    2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
117        Patch by Daniel Richard G.
119    3.  Single character iterator optimizations in the JIT compiler.
121    4.  Improved JIT compiler optimizations for character ranges.
123    5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
124        Reported by Giuseppe D'Angelo.
126    6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
127        of a line, was being set incorrectly in cases where .* appeared inside
128        atomic brackets at the start of a pattern, or where there was a subsequent
129        *PRUNE or *SKIP.
131    7.  Improved instruction cache flush for POWER/PowerPC.
132        Patch by Daniel Richard G.
134    8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
135        grep:
137        (a) There is now no limit to the number of patterns to be matched.
139        (b) An error is given if a pattern is too long.
141        (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
142            are now supported.
144        (d) --exclude-from and --include-from (multiple use) have been added.
146        (e) Exclusions and inclusions now apply to all files and directories, not
147            just to those obtained from scanning a directory recursively.
149        (f) Multiple uses of -f and --file-list are now supported.
151        (g) In a Windows environment, the default for -d has been changed from
152            "read" (the GNU grep default) to "skip", because otherwise the presence
153            of a directory in the file list provokes an error.
155        (h) The documentation has been revised and clarified in places.
157    9.  Improve the matching speed of capturing brackets.
159    10. Changed the meaning of \X so that it now matches a Unicode extended
160        grapheme cluster.
162    11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
163        out POSIX threads when JIT support is configured.
165    12. Added support for PCRE_STUDY_EXTRA_NEEDED.
167    13. In the POSIX wrapper regcomp() function, setting re_nsub field in the preg
168        structure could go wrong in environments where size_t is not the same size
169        as int.
171    14. Applied user-supplied patch to pcrecpp.cc to allow PCRE_NO_UTF8_CHECK to be
172        set.
174    15. The EBCDIC support had decayed; later updates to the code had included
175        explicit references to (e.g.) \x0a instead of CHAR_LF. There has been a
176        general tidy up of EBCDIC-related issues, and the documentation was also
177        not quite right. There is now a test that can be run on ASCII systems to
178        check some of the EBCDIC-related things (but is it not a full test).
180    16. The new PCRE_STUDY_EXTRA_NEEDED option is now used by pcregrep, resulting
181        in a small tidy to the code.
183    17. Fix JIT tests when UTF is disabled and both 8 and 16 bit mode are enabled.
185    18. If the --only-matching (-o) option in pcregrep is specified multiple
186        times, each one causes appropriate output. For example, -o1 -o2 outputs the
187        substrings matched by the 1st and 2nd capturing parentheses. A separating
188        string can be specified by --om-separator (default empty).
190    19. Improving the first n character searches.
192    20. Turn case lists for horizontal and vertical white space into macros so that
193        they are defined only once.
195    21. This set of changes together give more compatible Unicode case-folding
196        behaviour for characters that have more than one other case when UCP
197        support is available.
199        (a) The Unicode property table now has offsets into a new table of sets of
200            three or more characters that are case-equivalent. The MultiStage2.py
201            script that generates these tables (the pcre_ucd.c file) now scans
202            CaseFolding.txt instead of UnicodeData.txt for character case
203            information.
205        (b) The code for adding characters or ranges of characters to a character
206            class has been abstracted into a generalized function that also handles
207            case-independence. In UTF-mode with UCP support, this uses the new data
208            to handle characters with more than one other case.
210        (c) A bug that is fixed as a result of (b) is that codepoints less than 256
211            whose other case is greater than 256 are now correctly matched
212            caselessly. Previously, the high codepoint matched the low one, but not
213            vice versa.
215        (d) The processing of \h, \H, \v, and \ in character classes now makes use
216            of the new class addition function, using character lists defined as
217            macros alongside the case definitions of 20 above.
219        (e) Caseless back references now work with characters that have more than
220            one other case.
222        (f) General caseless matching of characters with more than one other case
223            is supported.
225    22. Unicode character properties were updated from Unicode 6.2.0
227    23. Improved CMake support under Windows. Patch by Daniel Richard G.
229    24. Add support for 32-bit character strings, and UTF-32
231    25. Major JIT compiler update (code refactoring and bugfixing).
232        Experimental Sparc 32 support is added.
234    26. Applied a modified version of Daniel Richard G's patch to create
235        pcre.h.generic and config.h.generic by "make" instead of in the
236        PrepareRelease script.
238    27. Added a definition for CHAR_NULL (helpful for the z/OS port), and use it in
239        pcre_compile.c when checking for a zero character.
241    28. Introducing a native interface for JIT. Through this interface, the compiled
242        machine code can be directly executed. The purpose of this interface is to
243        provide fast pattern matching, so several sanity checks are not performed.
244        However, feature tests are still performed. The new interface provides
245        1.4x speedup compared to the old one.
247    29. If pcre_exec() or pcre_dfa_exec() was called with a negative value for
248        the subject string length, the error given was PCRE_ERROR_BADOFFSET, which
249        was confusing. There is now a new error PCRE_ERROR_BADLENGTH for this case.
251    30. In 8-bit UTF-8 mode, pcretest failed to give an error for data codepoints
252        greater than 0x7fffffff (which cannot be represented in UTF-8, even under
253        the "old" RFC 2279). Instead, it ended up passing a negative length to
254        pcre_exec().
256    31. Add support for GCC's visibility feature to hide internal functions.
258    32. Running "pcretest -C pcre8" or "pcretest -C pcre16" gave a spurious error
259        "unknown -C option" after outputting 0 or 1.
261    33. There is now support for generating a code coverage report for the test
262        suite in environments where gcc is the compiler and lcov is installed. This
263        is mainly for the benefit of the developers.
265    34. If PCRE is built with --enable-valgrind, certain memory regions are marked
266        unaddressable using valgrind annotations, allowing valgrind to detect
267        invalid memory accesses. This is mainly for the benefit of the developers.
269    25. (*UTF) can now be used to start a pattern in any of the three libraries.
271    26. Give configure error if --enable-cpp but no C++ compiler found.
274    Version 8.31 06-July-2012
275    -------------------------
277    1.  Fixing a wrong JIT test case and some compiler warnings.
279    2.  Removed a bashism from the RunTest script.
281    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
282        to unsigned type, result still unsigned" that was given by an MS compiler
283        on encountering the code "-sizeof(xxx)".
285    4.  Partial matching support is added to the JIT compiler.
287    5.  Fixed several bugs concerned with partial matching of items that consist
288        of more than one character:
290        (a) /^(..)\1/ did not partially match "aba" because checking references was
291            done on an "all or nothing" basis. This also applied to repeated
292            references.
294        (b) \R did not give a hard partial match if \r was found at the end of the
295            subject.
297        (c) \X did not give a hard partial match after matching one or more
298            characters at the end of the subject.
300        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
301            a partial match for the string "\r".
303        (e) When newline was set to CRLF, the metacharacter "." did not recognize
304            a partial match for a CR character at the end of the subject string.
306    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
307        running pcretest, the text "(JIT)" added to the output whenever JIT is
308        actually used to run the match.
310    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
311        or /S+[+] with a digit between 1 and 7.
313    8.  OP_NOT now supports any UTF character not just single-byte ones.
315    9.  (*MARK) control verb is now supported by the JIT compiler.
317    10. The command "./RunTest list" lists the available tests without actually
318        running any of them. (Because I keep forgetting what they all are.)
322    12. Applied a (slightly modified) user-supplied patch that improves performance
323        when the heap is used for recursion (compiled with --disable-stack-for-
324        recursion). Instead of malloc and free for each heap frame each time a
325        logical recursion happens, frames are retained on a chain and re-used where
326        possible. This sometimes gives as much as 30% improvement.
328    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
329        call.
331    14. As documented, (*COMMIT) is now confined to within a positive assertion.
333    15. It is now possible to link pcretest with libedit as an alternative to
334        libreadline.
336    16. (*COMMIT) control verb is now supported by the JIT compiler.
338    17. The Unicode data tables have been updated to Unicode 6.1.0.
340    18. Added --file-list option to pcregrep.
342    19. Added binary file support to pcregrep, including the -a, --binary-files,
343        -I, and --text options.
345    20. The madvise function is renamed for posix_madvise for QNX compatibility
346        reasons. Fixed by Giuseppe D'Angelo.
348    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
350    22. Changed the option for creating symbolic links for 16-bit man pages from
351        -s to -sf so that re-installing does not cause issues.
353    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
355    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
356        matches in certain environments (the workspace was not being correctly
357        retained). Also added to pcre_dfa_exec() a simple plausibility check on
358        some of the workspace data at the beginning of a restart.
360    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
361        was not doing so when it should - probably a typo introduced by SVN 528
362        (change 8.10/14).
364    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
365        \w+ when the character tables indicated that \x{c4} was a word character.
366        There were several related cases, all because the tests for doing a table
367        lookup were testing for characters less than 127 instead of 255.
369    27. If a pattern contains capturing parentheses that are not used in a match,
370        their slots in the ovector are set to -1. For those that are higher than
371        any matched groups, this happens at the end of processing. In the case when
372        there were back references that the ovector was too small to contain
373        (causing temporary malloc'd memory to be used during matching), and the
374        highest capturing number was not used, memory off the end of the ovector
375        was incorrectly being set to -1. (It was using the size of the temporary
376        memory instead of the true size.)
378    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
379        ovector size, it uses memory at the end of the block that it has got.
381    29. Check for an overlong MARK name and give an error at compile time. The
382        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
384    30. JIT compiler update.
386    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
387        Rill for the patch.
389    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
391    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
393    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
394        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
395        was enabled.
397    35. Improve JIT code generation for greedy plus quantifier.
399    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
400        1 to "aa" instead of to an empty string. The bug affected repeated groups
401        that could potentially match an empty string.
403    37. Optimizing single character iterators in JIT.
405    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
406        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
407        codepoints that are too big for the mode are faulted, and in a UTF mode,
408        disallowed codepoints are also faulted.
410    39. If PCRE was compiled with UTF support, in three places in the DFA
411        matcher there was code that should only have been obeyed in UTF mode, but
412        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
413        processing when bytes with values greater than 127 were present. In 16-bit
414        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
415        both cases the values are those that cannot be the first data item in a UTF
416        character. The three items that might have provoked this were recursions,
417        possessively repeated groups, and atomic groups.
419    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
420        and pcregrep, because some OS require shared objects to be explicitly
421        passed to ld, causing the link step to fail if they are not.
423    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
424        mode, patterns that started with \h* or \R* might be incorrectly matched.
427    Version 8.30 04-February-2012
428    -----------------------------
430    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
431        name is defined in ctype.h.
433    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
434        only in quite long subpatterns.
436    3.  Removed the function pcre_info(), which has been obsolete and deprecated
437        since it was replaced by pcre_fullinfo() in February 2000.
439    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
440        match a (*MARK), and the match failed at the start of the subject, a
441        reference to memory before the start of the subject could occur. This bug
442        was introduced by fix 17 of release 8.21.
444    5.  A reference to an unset group with zero minimum repetition was giving
445        totally wrong answers (in non-JavaScript-compatibility mode). For example,
446        /(another)?(\1?)test/ matched against "hello world test". This bug was
447        introduced in release 8.13.
449    6.  Add support for 16-bit character strings (a large amount of work involving
450        many changes and refactorings).
452    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
453        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
454        from a file.
456    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
457        rounding is not applied in this particular case).
459    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
460        if they appear, or are escaped, in patterns.
462    10. Get rid of a number of -Wunused-but-set-variable warnings.
464    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
465        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
466        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
467        also returns the mark "x". This bug applied to capturing parentheses,
468        non-capturing parentheses, and atomic parentheses. It also applied to some
469        assertions.
471    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
472        information out of configure.ac instead of relying on pcre.h.generic, which
473        is not stored in the repository.
475    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
476        -lreadline.
478    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
480    15. Applied Graycode's patch to put the top-level frame on the stack rather
481        than the heap when not using the stack for recursion. This gives a
482        performance improvement in many cases when recursion is not deep.
484    16. Experimental code added to "pcretest -C" to output the stack frame size.
487    Version 8.21 12-Dec-2011
488    ------------------------
490    1.  Updating the JIT compiler.
492    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
493        are added as well.
495    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
496        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
497        calling _pcre_jit_exec. Some extra comments are added.
499    4.  (*MARK) settings inside atomic groups that do not contain any capturing
500        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
501        was introduced by change 18 for 8.20.
503    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
504        ECMA-262 standard.
506    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
507        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
508        This bug was probably introduced by change 9 of 8.13.
510    7.  While fixing 6 above, I noticed that a number of other items were being
511        incorrectly rejected as "not fixed length". This arose partly because newer
512        opcodes had not been added to the fixed-length checking code. I have (a)
513        corrected the bug and added tests for these items, and (b) arranged for an
514        error to occur if an unknown opcode is encountered while checking for fixed
515        length instead of just assuming "not fixed length". The items that were
516        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
517        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
518        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
520    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
521        being incorrectly compiled and would have given unpredicatble results.
523    9.  A possessively repeated subpattern with minimum repeat count greater than
524        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
525        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
526        the first (A) could occur when it should not.
528    10. Add a cast and remove a redundant test from the code.
530    11. JIT should use pcre_malloc/pcre_free for allocation.
532    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
533        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
534        is anything other than /usr, -L is still shown).
536    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
538    14. Perl does not support \N without a following name in a [] class; PCRE now
539        also gives an error.
541    15. If a forward reference was repeated with an upper limit of around 2000,
542        it caused the error "internal error: overran compiling workspace". The
543        maximum number of forward references (including repeats) was limited by the
544        internal workspace, and dependent on the LINK_SIZE. The code has been
545        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
546        the default depends on LINK_SIZE. There is a new upper limit (for safety)
547        of around 200,000 forward references. While doing this, I also speeded up
548        the filling in of repeated forward references.
550    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
551        incorrectly expecting the subject to contain another "a" after the start.
553    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
554        in the match, the SKIP should be ignored. This was not happening; instead
555        the SKIP was being treated as NOMATCH. For patterns such as
556        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
557        tested.
559    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
560        now much more compatible with Perl, in particular in cases where the result
561        is a non-match for a non-anchored pattern. For example, if
562        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
563        "m", where previously it did not return a name. A side effect of this
564        change is that for partial matches, the last encountered mark name is
565        returned, as for non matches. A number of tests that were previously not
566        Perl-compatible have been moved into the Perl-compatible test files. The
567        refactoring has had the pleasing side effect of removing one argument from
568        the match() function, thus reducing its stack requirements.
570    19. If the /S+ option was used in pcretest to study a pattern using JIT,
571        subsequent uses of /S (without +) incorrectly behaved like /S+.
573    21. Retrieve executable code size support for the JIT compiler and fixing
574        some warnings.
576    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
577        not work when the shorter character appeared right at the end of the
578        subject string.
580    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
581        systems.
583    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
584        output it when the /M option is used in pcretest.
586    25. The CheckMan script was not being included in the distribution. Also, added
587        an explicit "perl" to run Perl scripts from the PrepareRelease script
588        because this is reportedly needed in Windows.
590    26. If study data was being save in a file and studying had not found a set of
591        "starts with" bytes for the pattern, the data written to the file (though
592        never used) was taken from uninitialized memory and so caused valgrind to
593        complain.
595    27. Updated RunTest.bat as provided by Sheri Pierce.
597    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
599    29. Computation of memory usage for the table of capturing group names was
600        giving an unnecessarily large value.
603    Version 8.20 21-Oct-2011
604    ------------------------
606    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
607        a POSIX class. After further experiments with Perl, which convinced me that
608        Perl has bugs and confusions, a closing square bracket is no longer allowed
609        in a POSIX name. This bug also affected patterns with classes that started
610        with full stops.
612    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
613        captured substring, but while checking the failing first alternative,
614        substring 1 is temporarily captured. If the output vector supplied to
615        pcre_exec() was not big enough for this capture, the yield of the function
616        was still zero ("insufficient space for captured substrings"). This cannot
617        be totally fixed without adding another stack variable, which seems a lot
618        of expense for a edge case. However, I have improved the situation in cases
619        such as /(a)(b)x|abc/ matched against "abc", where the return code
620        indicates that fewer than the maximum number of slots in the ovector have
621        been set.
623    3.  Related to (2) above: when there are more back references in a pattern than
624        slots in the output vector, pcre_exec() uses temporary memory during
625        matching, and copies in the captures as far as possible afterwards. It was
626        using the entire output vector, but this conflicts with the specification
627        that only 2/3 is used for passing back captured substrings. Now it uses
628        only the first 2/3, for compatibility. This is, of course, another edge
629        case.
631    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
632        main code base, and can be used by building with --enable-jit. When this is
633        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
634        runtime --no-jit option is given.
636    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
637        ovector, the return from the function was zero, implying that there were
638        other matches that did not fit. The correct "exactly full" value is now
639        returned.
641    6.  If a subpattern that was called recursively or as a subroutine contained
642        (*PRUNE) or any other control that caused it to give a non-standard return,
643        invalid errors such as "Error -26 (nested recursion at the same subject
644        position)" or even infinite loops could occur.
646    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
647        computing the minimum length on reaching *ACCEPT, and so ended up with the
648        wrong value of 1 rather than 0. Further investigation indicates that
649        computing a minimum subject length in the presence of *ACCEPT is difficult
650        (think back references, subroutine calls), and so I have changed the code
651        so that no minimum is registered for a pattern that contains *ACCEPT.
653    8.  If (*THEN) was present in the first (true) branch of a conditional group,
654        it was not handled as intended. [But see 16 below.]
656    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
657        Sheri Pierce.
659    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
660        the first byte in a match must be "a".
662    11. Change 17 for 8.13 increased the recursion depth for patterns like
663        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
664        pattern contains any instances of (*THEN). If it does not, the old
665        optimizations are restored. It would be nice to do this on a per-group
666        basis, but at the moment that is not feasible.
668    12. In some environments, the output of pcretest -C is CRLF terminated. This
669        broke RunTest's code that checks for the link size. A single white space
670        character after the value is now allowed for.
672    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
673        For "fr", it uses the Windows-specific input and output files.
675    14. If (*THEN) appeared in a group that was called recursively or as a
676        subroutine, it did not work as intended. [But see next item.]
678    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
679        pattern fragments (but not containing any | characters). If A and B are
680        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
681        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
682        D. In other words, Perl considers parentheses that do not contain any |
683        characters to be part of a surrounding alternative, whereas PCRE was
684        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
685        differently. PCRE now behaves in the same way as Perl, except in the case
686        of subroutine/recursion calls such as (?1) which have in any case always
687        been different (but PCRE had them first :-).
689    16. Related to 15 above: Perl does not treat the | in a conditional group as
690        creating alternatives. Such a group is treated in the same way as an
691        ordinary group without any | characters when processing (*THEN). PCRE has
692        been changed to match Perl's behaviour.
694    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
695        RunGrepTest script failed.
697    18. Change 22 for version 13 caused atomic groups to use more stack. This is
698        inevitable for groups that contain captures, but it can lead to a lot of
699        stack use in large patterns. The old behaviour has been restored for atomic
700        groups that do not contain any capturing parentheses.
702    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
703        suppress the check for a minimum subject length at run time. (If it was
704        given to pcre_exec() or pcre_dfa_exec() it did work.)
706    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
707        fail to work when decoding hex characters in data strings in EBCDIC
708        environments.
710    21. It appears that in at least one Mac OS environment, the isxdigit() function
711        is implemented as a macro that evaluates to its argument more than once,
712        contravening the C 90 Standard (I haven't checked a later standard). There
713        was an instance in pcretest which caused it to go wrong when processing
714        \x{...} escapes in subject strings. The has been rewritten to avoid using
715        things like p++ in the argument of isxdigit().
718    Version 8.13 16-Aug-2011
719    ------------------------
721    1.  The Unicode data tables have been updated to Unicode 6.0.0.
723    2.  Two minor typos in pcre_internal.h have been fixed.
725    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
726        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
727        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
729    4.  There were a number of related bugs in the code for matching backrefences
730        caselessly in UTF-8 mode when codes for the characters concerned were
731        different numbers of bytes. For example, U+023A and U+2C65 are an upper
732        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
733        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
734        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
735        2-byte code at the end of the subject (it thought there wasn't enough data
736        left).
738    5.  Comprehensive information about what went wrong is now returned by
739        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
740        as the output vector has at least 2 elements. The offset of the start of
741        the failing character and a reason code are placed in the vector.
743    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
744        now returned is for the first byte of the failing character, instead of the
745        last byte inspected. This is an incompatible change, but I hope it is small
746        enough not to be a problem. It makes the returned offset consistent with
747        pcre_exec() and pcre_dfa_exec().
749    7.  pcretest now gives a text phrase as well as the error number when
750        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
751        failure, the offset and reason code are output.
753    8.  When \R was used with a maximizing quantifier it failed to skip backwards
754        over a \r\n pair if the subsequent match failed. Instead, it just skipped
755        back over a single character (\n). This seems wrong (because it treated the
756        two characters as a single entity when going forwards), conflicts with the
757        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
758        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
759        has been changed.
761    9.  Some internal refactoring has changed the processing so that the handling
762        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
763        time (the PCRE_DOTALL option was changed this way some time ago: version
764        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
765        which was always a bit of a fudge. It also means that there is one less
766        argument for the match() function, which reduces its stack requirements
767        slightly. This change also fixes an incompatibility with Perl: the pattern
768        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
770    10. More internal refactoring has drastically reduced the number of recursive
771        calls to match() for possessively repeated groups such as (abc)++ when
772        using pcre_exec().
774    11. While implementing 10, a number of bugs in the handling of groups were
775        discovered and fixed:
777        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
778        (a|)*(?1) gave a compile-time internal error.
779        ((a|)+)+  did not notice that the outer group could match an empty string.
780        (^a|^)+   was not marked as anchored.
781        (.*a|.*)+ was not marked as matching at start or after a newline.
783    12. Yet more internal refactoring has removed another argument from the match()
784        function. Special calls to this function are now indicated by setting a
785        value in a variable in the "match data" data block.
787    13. Be more explicit in pcre_study() instead of relying on "default" for
788        opcodes that mean there is no starting character; this means that when new
789        ones are added and accidentally left out of pcre_study(), testing should
790        pick them up.
792    14. The -s option of pcretest has been documented for ages as being an old
793        synonym of -m (show memory usage). I have changed it to mean "force study
794        for every regex", that is, assume /S for every regex. This is similar to -i
795        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
796        using it. It makes it easier to run collections of tests with and without
797        study enabled, and thereby test pcre_study() more easily. All the standard
798        tests are now run with and without -s (but some patterns can be marked as
799        "never study" - see 20 below).
801    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
802        restoration of the capturing data to the outer values was not happening
803        correctly.
805    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
806        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
807        pattern had matched an empty string, and so incorrectly returned a no
808        match.
810    17. There was optimizing code for the last branch of non-capturing parentheses,
811        and also for the obeyed branch of a conditional subexpression, which used
812        tail recursion to cut down on stack usage. Unfortunately, now that there is
813        the possibility of (*THEN) occurring in these branches, tail recursion is
814        no longer possible because the return has to be checked for (*THEN). These
815        two optimizations have therefore been removed. [But see 8.20/11 above.]
817    18. If a pattern containing \R was studied, it was assumed that \R always
818        matched two bytes, thus causing the minimum subject length to be
819        incorrectly computed because \R can also match just one byte.
821    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
822        was incorrectly computed.
824    20. If /S is present twice on a test pattern in pcretest input, it now
825        *disables* studying, thereby overriding the use of -s on the command line
826        (see 14 above). This is necessary for one or two tests to keep the output
827        identical in both cases.
829    21. When (*ACCEPT) was used in an assertion that matched an empty string and
830        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
832    22. When an atomic group that contained a capturing parenthesis was
833        successfully matched, but the branch in which it appeared failed, the
834        capturing was not being forgotten if a higher numbered group was later
835        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
836        group 1 to "a", when in fact it should be unset. This applied to multi-
837        branched capturing and non-capturing groups, repeated or not, and also to
838        positive assertions (capturing in negative assertions does not happen
839        in PCRE) and also to nested atomic groups.
841    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
842        subject after a captured substring, to make it easier to tell which of a
843        number of identical substrings has been captured.
845    24. The way atomic groups are processed by pcre_exec() has been changed so that
846        if they are repeated, backtracking one repetition now resets captured
847        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
848        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
849        "aaa". Previously, it would have been "a". As part of this code
850        refactoring, the way recursive calls are handled has also been changed.
852    25. If an assertion condition captured any substrings, they were not passed
853        back unless some other capturing happened later. For example, if
854        (?(?=(a))a) was matched against "a", no capturing was returned.
856    26. When studying a pattern that contained subroutine calls or assertions,
857        the code for finding the minimum length of a possible match was handling
858        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
859        group 1 called group 2 while simultaneously a separate group 2 called group
860        1). A stack overflow occurred in this case. I have fixed this by limiting
861        the recursion depth to 10.
863    27. Updated RunTest.bat in the distribution to the version supplied by Tom
864        Fortmann. This supports explicit test numbers on the command line, and has
865        argument validation and error reporting.
867    28. An instance of \X with an unlimited repeat could fail if at any point the
868        first character it looked at was a mark character.
870    29. Some minor code refactoring concerning Unicode properties and scripts
871        should reduce the stack requirement of match() slightly.
873    30. Added the '=' option to pcretest to check the setting of unused capturing
874        slots at the end of the pattern, which are documented as being -1, but are
875        not included in the return count.
877    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
878        compiled something random. Now it gives a compile-time error (as does
879        Perl).
881    32. A *MARK encountered during the processing of a positive assertion is now
882        recorded and passed back (compatible with Perl).
884    33. If --only-matching or --colour was set on a pcregrep call whose pattern
885        had alternative anchored branches, the search for a second match in a line
886        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
887        matched the line "0102" twice. The same bug affected patterns that started
888        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
889        twice.
891    34. Previously, PCRE did not allow quantification of assertions. However, Perl
892        does, and because of capturing effects, quantifying parenthesized
893        assertions may at times be useful. Quantifiers are now allowed for
894        parenthesized assertions.
896    35. A minor code tidy in pcre_compile() when checking options for \R usage.
898    36. \g was being checked for fancy things in a character class, when it should
899        just be a literal "g".
901    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
902        appearance of a nested POSIX class supersedes an apparent external class.
903        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
904        unescaped square brackets may also appear as part of class names. For
905        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
906        more like Perl. (But see 8.20/1 above.)
908    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
909        was because it thought it was \N{name}, which is not supported).
911    39. Add minix to OS list not supporting the -S option in pcretest.
913    40. PCRE tries to detect cases of infinite recursion at compile time, but it
914        cannot analyze patterns in sufficient detail to catch mutual recursions
915        such as ((?1))((?2)). There is now a runtime test that gives an error if a
916        subgroup is called recursively as a subpattern for a second time at the
917        same position in the subject string. In previous releases this might have
918        been caught by the recursion limit, or it might have run out of stack.
920    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
921        happen only once. PCRE was, however incorrectly giving a compile time error
922        "recursive call could loop indefinitely" because it cannot analyze the
923        pattern in sufficient detail. The compile time test no longer happens when
924        PCRE is compiling a conditional subpattern, but actual runaway loops are
925        now caught at runtime (see 40 above).
927    42. It seems that Perl allows any characters other than a closing parenthesis
928        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
929        has been changed to be the same.
931    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
932        as not to get warnings when autogen.sh is called. Also changed
933        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
935    44. To help people who use pcregrep to scan files containing exceedingly long
936        lines, the following changes have been made:
938        (a) The default value of the buffer size parameter has been increased from
939            8K to 20K. (The actual buffer used is three times this size.)
941        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
942            PCRE is built.
944        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
945            to be set at run time.
947        (d) Numerical values in pcregrep options can be followed by K or M, for
948            example --buffer-size=50K.
950        (e) If a line being scanned overflows pcregrep's buffer, an error is now
951            given and the return code is set to 2.
953    45. Add a pointer to the latest mark to the callout data block.
955    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
956        partial match of an empty string instead of no match. This was specific to
957        the use of ".".
959    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
960        complete match instead of a partial match. This bug was dependent on both
961        the PCRE_UTF8 and PCRE_DOTALL options being set.
963    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
964        starting byte set, because \b was not being ignored.
967    Version 8.12 15-Jan-2011
968    ------------------------
970    1.  Fixed some typos in the markup of the man pages, and wrote a script that
971        checks for such things as part of the documentation building process.
973    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
974        --match-limit and --recursion-limit options (added for 8.11). In
975        particular, this made one of the standard tests fail. (The integer value
976        went into the wrong half of a long int.)
978    3.  If the --colour option was given to pcregrep with -v (invert match), it
979        did strange things, either producing crazy output, or crashing. It should,
980        of course, ignore a request for colour when reporting lines that do not
981        match.
983    4.  Another pcregrep bug caused similar problems if --colour was specified with
984        -M (multiline) and the pattern match finished with a line ending.
986    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
987        matched in multiline mode, the following line was shown as part of the
988        match. This seems wrong, so I have changed it.
990    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
991        the check for further matches in the same line (so they could be coloured)
992        to overrun the end of the current line. If another match was found, it was
993        incorrectly shown (and then shown again when found in the next line).
995    7.  If pcregrep was compiled under Windows, there was a reference to the
996        function pcregrep_exit() before it was defined. I am assuming this was
997        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
998        reported by a user. I've moved the definition above the reference.
1001    Version 8.11 10-Dec-2010
1002    ------------------------
1004    1.  (*THEN) was not working properly if there were untried alternatives prior
1005        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
1006        backtracked to try for "b" instead of moving to the next alternative branch
1007        at the same level (in this case, to look for "c"). The Perl documentation
1008        is clear that when (*THEN) is backtracked onto, it goes to the "next
1009        alternative in the innermost enclosing group".
1011    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
1012        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
1013        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
1014        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
1015        (*THEN).
1017    3.  If \s appeared in a character class, it removed the VT character from
1018        the class, even if it had been included by some previous item, for example
1019        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
1020        of \s, but is part of the POSIX "space" class.)
1022    4.  A partial match never returns an empty string (because you can always
1023        match an empty string at the end of the subject); however the checking for
1024        an empty string was starting at the "start of match" point. This has been
1025        changed to the "earliest inspected character" point, because the returned
1026        data for a partial match starts at this character. This means that, for
1027        example, /(?<=abc)def/ gives a partial match for the subject "abc"
1028        (previously it gave "no match").
1030    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
1031        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
1032        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
1033        has an implication that the given string is incomplete (because a partial
1034        match is preferred over a full match). For this reason, these items now
1035        give a partial match in this situation. [Aside: previously, the one case
1036        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
1037        match rather than a full match, which was wrong by the old rules, but is
1038        now correct.]
1040    6.  There was a bug in the handling of #-introduced comments, recognized when
1041        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
1042        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
1043        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
1044        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
1045        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
1046        places in pcre_compile().
1048    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
1049        comments when looking ahead for named forward references to subpatterns,
1050        the only newline sequence it recognized was NL. It now handles newlines
1051        according to the set newline convention.
1053    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
1054        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
1055        cater for a lack of strerror(). These oversights have been fixed.
1057    9.  Added --match-limit and --recursion-limit to pcregrep.
1059    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
1061    11. When the -o option was used, pcregrep was setting a return code of 1, even
1062        when matches were found, and --line-buffered was not being honoured.
1064    12. Added an optional parentheses number to the -o and --only-matching options
1065        of pcregrep.
1067    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
1068        can match an empty string. The code to do it in pcretest and pcredemo
1069        needed fixing:
1071        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
1072            only one byte after an empty string match just before CRLF (this case
1073            just got forgotten; "any" and "anycrlf" were OK).
1075        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
1076            mode when an empty string match preceded an ASCII character followed by
1077            a non-ASCII character. (The code for advancing by one character rather
1078            than one byte was nonsense.)
1080        (c) The pcredemo.c sample program did not have any code at all to handle
1081            the cases when CRLF is a valid newline sequence.
1083    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
1084        as a starting offset was within the subject string. There is now a new
1085        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
1086        negative or greater than the length of the string. In order to test this,
1087        pcretest is extended to allow the setting of negative starting offsets.
1089    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
1090        starting offset points to the beginning of a UTF-8 character was
1091        unnecessarily clumsy. I tidied it up.
1093    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
1094        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
1096    17. Nobody had reported that the --include_dir option, which was added in
1097        release 7.7 should have been called --include-dir (hyphen, not underscore)
1098        for compatibility with GNU grep. I have changed it to --include-dir, but
1099        left --include_dir as an undocumented synonym, and the same for
1100        --exclude-dir, though that is not available in GNU grep, at least as of
1101        release 2.5.4.
1103    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
1104        characters from a string of bytes) have been redefined so as not to use
1105        loops, in order to improve performance in some environments. At the same
1106        time, I abstracted some of the common code into auxiliary macros to save
1107        repetition (this should not affect the compiled code).
1109    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
1110        compile-time error is now given if \c is not followed by an ASCII
1111        character, that is, a byte less than 128. (In EBCDIC mode, the code is
1112        different, and any byte value is allowed.)
1114    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
1115        START_OPTIMIZE option, which is now allowed at compile time - but just
1116        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
1117        to pcregrep and other applications that have no direct access to PCRE
1118        options. The new /Y option in pcretest sets this option when calling
1119        pcre_compile().
1121    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
1122        back references. Groups containing recursive back references were forced to
1123        be atomic by that change, but in the case of named groups, the amount of
1124        memory required was incorrectly computed, leading to "Failed: internal
1125        error: code overflow". This has been fixed.
1127    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
1128        pcretest.c, to avoid build problems in some Borland environments.
1131    Version 8.10 25-Jun-2010
1132    ------------------------
1134    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
1135        THEN.
1137    2.  (*ACCEPT) was not working when inside an atomic group.
1139    3.  Inside a character class, \B is treated as a literal by default, but
1140        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
1141        causes the error). The code is unchanged, but I tidied the documentation.
1143    4.  Inside a character class, PCRE always treated \R and \X as literals,
1144        whereas Perl faults them if its -w option is set. I have changed PCRE so
1145        that it faults them when PCRE_EXTRA is set.
1147    5.  Added support for \N, which always matches any character other than
1148        newline. (It is the same as "." when PCRE_DOTALL is not set.)
1150    6.  When compiling pcregrep with newer versions of gcc which may have
1151        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
1152        declared with attribute warn_unused_result" were given. Just casting the
1153        result to (void) does not stop the warnings; a more elaborate fudge is
1154        needed. I've used a macro to implement this.
1156    7.  Minor change to pcretest.c to avoid a compiler warning.
1158    8.  Added four artifical Unicode properties to help with an option to make
1159        \s etc use properties (see next item). The new properties are: Xan
1160        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
1162    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
1163        use Unicode properties. (*UCP) at the start of a pattern can be used to set
1164        this option. Modified pcretest to add /W to test this facility. Added
1165        REG_UCP to make it available via the POSIX interface.
1167    10. Added --line-buffered to pcregrep.
1169    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
1170        studied, and the match started with a letter with a code point greater than
1171        127 whose first byte was different to the first byte of the other case of
1172        the letter, the other case of this starting letter was not recognized
1173        (#976).
1175    12. If a pattern that was studied started with a repeated Unicode property
1176        test, for example, \p{Nd}+, there was the theoretical possibility of
1177        setting up an incorrect bitmap of starting bytes, but fortunately it could
1178        not have actually happened in practice until change 8 above was made (it
1179        added property types that matched character-matching opcodes).
1181    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
1182        possible starting bytes for non-anchored patterns.
1184    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
1185        \R, and also a number of cases that involve Unicode properties, both
1186        explicit and implicit when PCRE_UCP is set.
1188    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
1189        input, it could crash or give wrong results if characters with values
1190        greater than 0xc0 were present in the subject string. (Detail: it assumed
1191        UTF-8 input when processing these items.)
1193    16. Added a lot of (int) casts to avoid compiler warnings in systems where
1194        size_t is 64-bit (#991).
1196    17. Added a check for running out of memory when PCRE is compiled with
1197        --disable-stack-for-recursion (#990).
1199    18. If the last data line in a file for pcretest does not have a newline on
1200        the end, a newline was missing in the output.
1202    19. The default pcre_chartables.c file recognizes only ASCII characters (values
1203        less than 128) in its various bitmaps. However, there is a facility for
1204        generating tables according to the current locale when PCRE is compiled. It
1205        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
1206        characters, are recognized by isspace() and therefore were getting set in
1207        these tables, and indeed these tables seem to approximate to ISO 8859. This
1208        caused a problem in UTF-8 mode when pcre_study() was used to create a list
1209        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
1210        which of course cannot start UTF-8 characters. I have changed the code so
1211        that only real ASCII characters (less than 128) and the correct starting
1212        bytes for UTF-8 encodings are set for characters greater than 127 when in
1213        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
1214        altogether.)
1216    20. Added the /T option to pcretest so as to be able to run tests with non-
1217        standard character tables, thus making it possible to include the tests
1218        used for 19 above in the standard set of tests.
1220    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
1221        reference to a subpattern the other side of a comment that contains an
1222        opening parenthesis caused either an internal compiling error, or a
1223        reference to the wrong subpattern.
1226    Version 8.02 19-Mar-2010
1227    ------------------------
1229    1.  The Unicode data tables have been updated to Unicode 5.2.0.
1231    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
1232        configured.
1234    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
1235        original author of that file, following a query about its status.
1237    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
1238        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
1240    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
1241        quantifier applied to a forward-referencing subroutine call, could compile
1242        incorrect code or give the error "internal error: previously-checked
1243        referenced subpattern not found".
1245    6.  Both MS Visual Studio and Symbian OS have problems with initializing
1246        variables to point to external functions. For these systems, therefore,
1247        pcre_malloc etc. are now initialized to local functions that call the
1248        relevant global functions.
1250    7.  There were two entries missing in the vectors called coptable and poptable
1251        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
1252        I've fixed the data, and added a kludgy way of testing at compile time that
1253        the lengths are correct (equal to the number of opcodes).
1255    8.  Following on from 7, I added a similar kludge to check the length of the
1256        eint vector in pcreposix.c.
1258    9.  Error texts for pcre_compile() are held as one long string to avoid too
1259        much relocation at load time. To find a text, the string is searched,
1260        counting zeros. There was no check for running off the end of the string,
1261        which could happen if a new error number was added without updating the
1262        string.
1264    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
1266    11. \K was not working if it appeared in an atomic group or in a group that
1267        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
1268        \K is "not well defined" if used in an assertion. PCRE now accepts it if
1269        the assertion is positive, but not if it is negative.
1271    12. Change 11 fortuitously reduced the size of the stack frame used in the
1272        "match()" function of pcre_exec.c by one pointer. Forthcoming
1273        implementation of support for (*MARK) will need an extra pointer on the
1274        stack; I have reserved it now, so that the stack frame size does not
1275        decrease.
1277    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
1278        item in branch that calls a recursion is a subroutine call - as in the
1279        second branch in the above example - was incorrectly given the compile-
1280        time error "recursive call could loop indefinitely" because pcre_compile()
1281        was not correctly checking the subroutine for matching a non-empty string.
1283    14. The checks for overrunning compiling workspace could trigger after an
1284        overrun had occurred. This is a "should never occur" error, but it can be
1285        triggered by pathological patterns such as hundreds of nested parentheses.
1286        The checks now trigger 100 bytes before the end of the workspace.
1288    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
1291    Version 8.01 19-Jan-2010
1292    ------------------------
1294    1.  If a pattern contained a conditional subpattern with only one branch (in
1295        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
1296        computed the wrong minimum data length (which is of course zero for such
1297        subpatterns). This could cause incorrect "no match" results.
1299    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
1300        the pattern is reset in the first branch, pcre_compile() failed with
1301        "internal error: code overflow at offset...". This happened only when
1302        the reset was to the original external option setting. (An optimization
1303        abstracts leading options settings into an external setting, which was the
1304        cause of this.)
1306    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
1307        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
1308        assertion pattern did not match (meaning that the assertion was true), it
1309        was incorrectly treated as false if the SKIP had been reached during the
1310        matching. This also applied to assertions used as conditions.
1312    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
1313        assertion subpattern, including such a pattern used as a condition,
1314        unpredictable results occurred, instead of the error return
1317    5.  The C++ GlobalReplace function was not working like Perl for the special
1318        situation when an empty string is matched. It now does the fancy magic
1319        stuff that is necessary.
1321    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
1322        removed. (These were left over from very, very early versions of PCRE.)
1324    7.  Some cosmetic changes to the code to make life easier when compiling it
1325        as part of something else:
1327        (a) Change DEBUG to PCRE_DEBUG.
1329        (b) In pcre_compile(), rename the member of the "branch_chain" structure
1330            called "current" as "current_branch", to prevent a collision with the
1331            Linux macro when compiled as a kernel module.
1333        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
1334            prevent a collision with the Linux macro when compiled as a kernel
1335            module.
1337    8.  In pcre_compile() there are some checks for integer overflows that used to
1338        cast potentially large values to (double). This has been changed to that
1339        when building, a check for int64_t is made, and if it is found, it is used
1340        instead, thus avoiding the use of floating point arithmetic. (There is no
1341        other use of FP in PCRE.) If int64_t is not found, the fallback is to
1342        double.
1344    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
1345        2005 (difference between two addresses compared to an unsigned value).
1347    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
1348        custom one, because of the following reported problem in Windows:
1350          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
1351              under Win32.
1352          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
1353              therefore missing the function definition.
1354          - The compiler thus generates a "C" signature for the test function.
1355          - The linker fails to find the "C" function.
1356          - PCRE fails to configure if asked to do so against libbz2.
1358    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
1359        messages were output:
1361          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
1362          rerunning libtoolize, to keep the correct libtool macros in-tree.
1363          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
1365        I have done both of these things.
1367    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
1368        most of the time, it *can* run out if it is given a pattern that contains a
1369        runaway infinite recursion. I updated the discussion in the pcrestack man
1370        page.
1372    13. Now that we have gone to the x.xx style of version numbers, the minor
1373        version may start with zero. Using 08 or 09 is a bad idea because users
1374        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
1375        interpreted as invalid octal numbers. I've updated the previous comment in
1376        configure.ac, and also added a check that gives an error if 08 or 09 are
1377        used.
1379    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
1380        causing partial matching to fail when the end of the subject matched \W
1381        in a UTF-8 pattern where \W was quantified with a minimum of 3.
1383    15. There were some discrepancies between the declarations in pcre_internal.h
1384        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
1385        their definitions. The declarations used "const uschar *" and the
1386        definitions used USPTR. Even though USPTR is normally defined as "const
1387        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
1388        reported that: "This difference in casting confuses some C++ compilers, for
1389        example, SunCC recognizes above declarations as different functions and
1390        generates broken code for hbpcre." I have changed the declarations to use
1391        USPTR.
1393    16. GNU libtool is named differently on some systems. The autogen.sh script now
1394        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
1395        (FreeBSD).
1397    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
1398        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
1399        comment: "Figure out how to create a longlong from a string: strtoll and
1400        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
1401        instance, but it only takes 2 args instead of 3!"
1403    18. A subtle bug concerned with back references has been fixed by a change of
1404        specification, with a corresponding code fix. A pattern such as
1405        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
1406        refers, was giving matches when it shouldn't. For example, xa=xaaa would
1407        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
1408        same bug. Such groups have to be quantified to be useful, or contained
1409        inside another quantified group. (If there's no repetition, the reference
1410        can never match.) The problem arises because, having left the group and
1411        moved on to the rest of the pattern, a later failure that backtracks into
1412        the group uses the captured value from the final iteration of the group
1413        rather than the correct earlier one. I have fixed this in PCRE by forcing
1414        any group that contains a reference to itself to be an atomic group; that
1415        is, there cannot be any backtracking into it once it has completed. This is
1416        similar to recursive and subroutine calls.
1419    Version 8.00 19-Oct-09
1420  ----------------------  ----------------------
1422  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
1423      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
1424      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
1425      error.      error.
1427  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
1428      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
1429      in a Windows environment.      in a Windows environment.
1431  3.  The pcregrep --count option prints the count for each file even when it is  3.  The pcregrep --count option prints the count for each file even when it is
1432      zero, as does GNU grep. However, pcregrep was also printing all files when      zero, as does GNU grep. However, pcregrep was also printing all files when
1433      --files-with-matches was added. Now, when both options are given, it prints      --files-with-matches was added. Now, when both options are given, it prints
1434      counts only for those files that have at least one match. (GNU grep just      counts only for those files that have at least one match. (GNU grep just
1435      prints the file name in this circumstance, but including the count seems      prints the file name in this circumstance, but including the count seems
1436      more useful - otherwise, why use --count?) Also ensured that the      more useful - otherwise, why use --count?) Also ensured that the
1437      combination -clh just lists non-zero counts, with no names.      combination -clh just lists non-zero counts, with no names.
1439  4.  The long form of the pcregrep -F option was incorrectly implemented as  4.  The long form of the pcregrep -F option was incorrectly implemented as
1440      --fixed_strings instead of --fixed-strings. This is an incompatible change,      --fixed_strings instead of --fixed-strings. This is an incompatible change,
1441      but it seems right to fix it, and I didn't think it was worth preserving      but it seems right to fix it, and I didn't think it was worth preserving
1442      the old behaviour.      the old behaviour.
1444  5.  The command line items --regex=pattern and --regexp=pattern were not  5.  The command line items --regex=pattern and --regexp=pattern were not
1445      recognized by pcregrep, which required --regex pattern or --regexp pattern      recognized by pcregrep, which required --regex pattern or --regexp pattern
1446      (with a space rather than an '='). The man page documented the '=' forms,      (with a space rather than an '='). The man page documented the '=' forms,
1447      which are compatible with GNU grep; these now work.      which are compatible with GNU grep; these now work.
1449  6.  No libpcreposix.pc file was created for pkg-config; there was just  6.  No libpcreposix.pc file was created for pkg-config; there was just
1450      libpcre.pc and libpcrecpp.pc. The omission has been rectified.      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
1452  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
1453      when UCP support is not needed, by modifying the Python script that      when UCP support is not needed, by modifying the Python script that
1454      generates it from Unicode data files. This should not matter if the module      generates it from Unicode data files. This should not matter if the module
1455      is correctly used as a library, but I received one complaint about 50K of      is correctly used as a library, but I received one complaint about 50K of
1456      unwanted data. My guess is that the person linked everything into his      unwanted data. My guess is that the person linked everything into his
1457      program rather than using a library. Anyway, it does no harm.      program rather than using a library. Anyway, it does no harm.
1459  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
1460      was a minimum greater than 1 for a wide character in a possessive      was a minimum greater than 1 for a wide character in a possessive
1461      repetition. Chaos could result.      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
1462        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
1463        character. Chaos in the form of incorrect output or a compiling loop could
1464        result.
1466  9.  The restrictions on what a pattern can contain when partial matching is  9.  The restrictions on what a pattern can contain when partial matching is
1467      requested for pcre_exec() have been removed. All patterns can now be      requested for pcre_exec() have been removed. All patterns can now be
1468      partially matched by this function. In addition, if there are at least two      partially matched by this function. In addition, if there are at least two
1469      slots in the offset vector, the offsets of the first-encountered partial      slots in the offset vector, the offset of the earliest inspected character
1470      match are set in them when PCRE_ERROR_PARTIAL is returned.      for the match and the offset of the end of the subject are set in them when
1471        PCRE_ERROR_PARTIAL is returned.
1473    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
1474        synonymous with PCRE_PARTIAL, for backwards compatibility, and
1475        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
1476        and may be more useful for multi-segment matching.
1478    11. Partial matching with pcre_exec() is now more intuitive. A partial match
1479        used to be given if ever the end of the subject was reached; now it is
1480        given only if matching could not proceed because another character was
1481        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
1482        string "Z", which now yields "no match" instead of "partial match". In the
1483        case of pcre_dfa_exec(), "no match" is given if every matching path for the
1484        final character ended with (*FAIL).
1486    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
1487        if the pattern had a "must contain" character that was already found in the
1488        earlier partial match, unless partial matching was again requested. For
1489        example, with the pattern /dog.(body)?/, the "must contain" character is
1490        "g". If the first part-match was for the string "dog", restarting with
1491        "sbody" failed. This bug has been fixed.
1493    13. The string returned by pcre_dfa_exec() after a partial match has been
1494        changed so that it starts at the first inspected character rather than the
1495        first character of the match. This makes a difference only if the pattern
1496        starts with a lookbehind assertion or \b or \B (\K is not supported by
1497        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1498        matching functions compatible, and I think it's the right thing to do.
1500    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1501        so that the demonstration program is easily available in environments where
1502        PCRE has not been installed from source.
1504    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1505        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1506        library.
1508    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1509        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1510        is not the first non-POSIX option to be added. Clearly some people find
1511        these options useful.
1513    17. If a caller to the POSIX matching function regexec() passes a non-zero
1514        value for nmatch with a NULL value for pmatch, the value of
1515        nmatch is forced to zero.
1517    18. RunGrepTest did not have a test for the availability of the -u option of
1518        the diff command, as RunTest does. It now checks in the same way as
1519        RunTest, and also checks for the -b option.
1521    19. If an odd number of negated classes containing just a single character
1522        interposed, within parentheses, between a forward reference to a named
1523        subpattern and the definition of the subpattern, compilation crashed with
1524        an internal error, complaining that it could not find the referenced
1525        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1526        [The bug was that it was starting one character too far in when skipping
1527        over the character class, thus treating the ] as data rather than
1528        terminating the class. This meant it could skip too much.]
1530    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1531        /g option in pcretest when the pattern contains \K, which makes it possible
1532        to have an empty string match not at the start, even when the pattern is
1533        anchored. Updated pcretest and pcredemo to use this option.
1535    21. If the maximum number of capturing subpatterns in a recursion was greater
1536        than the maximum at the outer level, the higher number was returned, but
1537        with unset values at the outer level. The correct (outer level) value is
1538        now given.
1540    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1541        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1542        make it do so. The string so far is captured, making this feature
1543        compatible with Perl.
1545    23. The tests have been re-organized, adding tests 11 and 12, to make it
1546        possible to check the Perl 5.10 features against Perl 5.10.
1548    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1549        pattern matches a fixed length string. PCRE did not allow this; now it
1550        does. Neither allows recursion.
1552    25. I finally figured out how to implement a request to provide the minimum
1553        length of subject string that was needed in order to match a given pattern.
1554        (It was back references and recursion that I had previously got hung up
1555        on.) This code has now been added to pcre_study(); it finds a lower bound
1556        to the length of subject needed. It is not necessarily the greatest lower
1557        bound, but using it to avoid searching strings that are too short does give
1558        some useful speed-ups. The value is available to calling programs via
1559        pcre_fullinfo().
1561    26. While implementing 25, I discovered to my embarrassment that pcretest had
1562        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1563        study optimizations had never been tested with that matching function.
1564        Oops. What is worse, even when it was passed study data, there was a bug in
1565        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1566        were also very few tests of studied patterns with pcre_dfa_exec().
1568    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1569        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1570        on the other side of the coin, they are no longer allowed to have different
1571        names, because these cannot be distinguished in PCRE, and this has caused
1572        confusion. (This is a difference from Perl.)
1574    28. When duplicate subpattern names are present (necessarily with different
1575        numbers, as required by 27 above), and a test is made by name in a
1576        conditional pattern, either for a subpattern having been matched, or for
1577        recursion in such a pattern, all the associated numbered subpatterns are
1578        tested, and the overall condition is true if the condition is true for any
1579        one of them. This is the way Perl works, and is also more like the way
1580        testing by number works.
1583  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
1584  ---------------------  ---------------------

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