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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.7 05-Mar-08  Version 8.34 xx-xxxx-201x
5    --------------------------
6    
7    1.  Add pcre[16|32]_jit_free_unused_memory to forcibly free unused JIT
8        executable memory. Patch inspired by Carsten Klein.
9    
10    2.  ./configure --enable-coverage defined SUPPORT_GCOV in config.h, although
11        this macro is never tested and has no effect, because the work to support
12        coverage involves only compiling and linking options and special targets in
13        the Makefile. The comment in config.h implied that defining the macro would
14        enable coverage support, which is totally false. There was also support for
15        setting this macro in the CMake files (my fault, I just copied it from
16        configure). SUPPORT_GCOV has now been removed.
17    
18    3.  Make a small performance improvement in strlen16() and strlen32() in
19        pcretest.
20    
21    4.  Change 36 for 8.33 left some unreachable statements in pcre_exec.c,
22        detected by the Solaris compiler (gcc doesn't seem to be able to diagnose
23        these cases). There was also one in pcretest.c.
24    
25    5.  Cleaned up a "may be uninitialized" compiler warning in pcre_exec.c.
26    
27    6.  In UTF mode, the code for checking whether a group could match an empty
28        string (which is used for indefinitely repeated groups to allow for
29        breaking an infinite loop) was broken when the group contained a repeated
30        negated single-character class with a character that occupied more than one
31        data item and had a minimum repetition of zero (for example, [^\x{100}]* in
32        UTF-8 mode). The effect was undefined: the group might or might not be
33        deemed as matching an empty string, or the program might have crashed.
34    
35    7.  The code for checking whether a group could match an empty string was not
36        recognizing that \h, \H, \v, \V, and \R must match a character.
37    
38    8.  Implemented PCRE_INFO_MATCH_EMPTY, which yields 1 if the pattern can match
39        an empty string. If it can, pcretest shows this in its information output.
40    
41    9.  Fixed two related bugs that applied to Unicode extended grapheme clusters
42        that were repeated with a maximizing qualifier (e.g. \X* or \X{2,5}) when
43        matched by pcre_exec() without using JIT:
44    
45        (a) If the rest of the pattern did not match after a maximal run of
46            grapheme clusters, the code for backing up to try with fewer of them
47            did not always back up over a full grapheme when characters that do not
48            have the modifier quality were involved, e.g. Hangul syllables.
49    
50        (b) If the match point in a subject started with modifier character, and
51            there was no match, the code could incorrectly back up beyond the match
52            point, and potentially beyond the first character in the subject,
53            leading to a segfault or an incorrect match result.
54    
55    10. A conditional group with an assertion condition could lead to PCRE
56        recording an incorrect first data item for a match if no other first data
57        item was recorded. For example, the pattern (?(?=ab)ab) recorded "a" as a
58        first data item, and therefore matched "ca" after "c" instead of at the
59        start.
60    
61    11. Change 40 for 8.33 (allowing pcregrep to find empty strings) showed up a
62        bug that caused the command "echo a | ./pcregrep -M '|a'" to loop.
63    
64    12. The source of pcregrep now includes z/OS-specific code so that it can be
65        compiled for z/OS as part of the special z/OS distribution.
66    
67    13. Added the -T and -TM options to pcretest.
68    
69    14. The code in pcre_compile.c for creating the table of named capturing groups
70        has been refactored. Instead of creating the table dynamically during the
71        actual compiling pass, the information is remembered during the pre-compile
72        pass (on the stack unless there are more than 20 named groups, in which
73        case malloc() is used) and the whole table is created before the actual
74        compile happens. This has simplified the code (it is now nearly 150 lines
75        shorter) and prepared the way for better handling of references to groups
76        with duplicate names.
77    
78    15. A back reference to a named subpattern when there is more than one of the
79        same name now checks them in the order in which they appear in the pattern.
80        The first one that is set is used for the reference. Previously only the
81        first one was inspected. This change makes PCRE more compatible with Perl.
82    
83    16. Unicode character properties were updated from Unicode 6.3.0.
84    
85    17. The compile-time code for auto-possessification has been refactored, based
86        on a patch by Zoltan Herczeg. It now happens after instead of during
87        compilation. The code is cleaner, and more cases are handled. The option
88        PCRE_NO_AUTO_POSSESSIFY is added for testing purposes, and the -O and /O
89        options in pcretest are provided to set it.
90    
91    18. The character VT has been added to the set of characters that match \s and
92        are generally treated as white space, following this same change in Perl
93        5.18. There is now no difference between "Perl space" and "POSIX space".
94    
95    19. The code for checking named groups as conditions, either for being set or
96        for being recursed, has been refactored (this is related to 14 and 15
97        above). Processing unduplicated named groups should now be as fast at
98        numerical groups, and processing duplicated groups should be faster than
99        before.
100    
101    20. Two patches to the CMake build system, by Alexander Barkov:
102    
103          (1) Replace the "source" command by "." in CMakeLists.txt because
104              "source" is a bash-ism.
105    
106          (2) Add missing HAVE_STDINT_H and HAVE_INTTYPES_H to config-cmake.h.in;
107              without these the CMake build does not work on Solaris.
108    
109    21. Perl has changed its handling of \8 and \9. If there is no previously
110        encountered capturing group of those numbers, they are treated as the
111        literal characters 8 and 9 instead of a binary zero followed by the
112        literals. PCRE now does the same.
113    
114    22. Following Perl, added \o{} to specify codepoints in octal, making it
115        possible to specify values greater than 0777 and also making them
116        unambiguous.
117    
118    23. Perl now gives an error for missing closing braces after \x{... instead of
119        treating the string as literal. PCRE now does the same.
120    
121    24. RunTest used to grumble if an inappropriate test was selected explicitly,
122        but just skip it when running all tests. This make it awkward to run ranges
123        of tests when one of them was inappropriate. Now it just skips any
124        inappropriate tests, as it always did when running all tests.
125    
126    25. If PCRE_AUTO_CALLOUT and PCRE_UCP were set for a pattern that contained
127        character types such as \d or \w, too many callouts were inserted, and the
128        data that they returned was rubbish.
129    
130    26. In UCP mode, \s was not matching two of the characters that Perl matches,
131        namely NEL (U+0085) and MONGOLIAN VOWEL SEPARATOR (U+180E), though they
132        were matched by \h. The code has now been refactored so that the lists of
133        the horizontal and vertical whitespace characters used for \h and \v (which
134        are defined only in one place) are now also used for \s.
135    
136    27. Add JIT support for the 64 bit TileGX architecture.
137        Patch by Jiong Wang (Tilera Corporation).
138    
139    28. Possessive quantifiers for classes (both explicit and automatically
140        generated) now use special opcodes instead of wrapping in ONCE brackets.
141    
142    29. Whereas an item such as A{4}+ ignored the possessivenes of the quantifier
143        (because it's meaningless), this was not happening when PCRE_CASELESS was
144        set. Not wrong, but inefficient.
145    
146    
147    Version 8.33 28-May-2013
148    ------------------------
149    
150    1.  Added 'U' to some constants that are compared to unsigned integers, to
151        avoid compiler signed/unsigned warnings. Added (int) casts to unsigned
152        variables that are added to signed variables, to ensure the result is
153        signed and can be negated.
154    
155    2.  Applied patch by Daniel Richard G for quashing MSVC warnings to the
156        CMake config files.
157    
158    3.  Revise the creation of config.h.generic so that all boolean macros are
159        #undefined, whereas non-boolean macros are #ifndef/#endif-ed. This makes
160        overriding via -D on the command line possible.
161    
162    4.  Changing the definition of the variable "op" in pcre_exec.c from pcre_uchar
163        to unsigned int is reported to make a quite noticeable speed difference in
164        a specific Windows environment. Testing on Linux did also appear to show
165        some benefit (and it is clearly not harmful). Also fixed the definition of
166        Xop which should be unsigned.
167    
168    5.  Related to (4), changing the definition of the intermediate variable cc
169        in repeated character loops from pcre_uchar to pcre_uint32 also gave speed
170        improvements.
171    
172    6.  Fix forward search in JIT when link size is 3 or greater. Also removed some
173        unnecessary spaces.
174    
175    7.  Adjust autogen.sh and configure.ac to lose warnings given by automake 1.12
176        and later.
177    
178    8.  Fix two buffer over read issues in 16 and 32 bit modes. Affects JIT only.
179    
180    9.  Optimizing fast_forward_start_bits in JIT.
181    
182    10. Adding support for callouts in JIT, and fixing some issues revealed
183        during this work. Namely:
184    
185        (a) Unoptimized capturing brackets incorrectly reset on backtrack.
186    
187        (b) Minimum length was not checked before the matching is started.
188    
189    11. The value of capture_last that is passed to callouts was incorrect in some
190        cases when there was a capture on one path that was subsequently abandoned
191        after a backtrack. Also, the capture_last value is now reset after a
192        recursion, since all captures are also reset in this case.
193    
194    12. The interpreter no longer returns the "too many substrings" error in the
195        case when an overflowing capture is in a branch that is subsequently
196        abandoned after a backtrack.
197    
198    13. In the pathological case when an offset vector of size 2 is used, pcretest
199        now prints out the matched string after a yield of 0 or 1.
200    
201    14. Inlining subpatterns in recursions, when certain conditions are fulfilled.
202        Only supported by the JIT compiler at the moment.
203    
204    15. JIT compiler now supports 32 bit Macs thanks to Lawrence Velazquez.
205    
206    16. Partial matches now set offsets[2] to the "bumpalong" value, that is, the
207        offset of the starting point of the matching process, provided the offsets
208        vector is large enough.
209    
210    17. The \A escape now records a lookbehind value of 1, though its execution
211        does not actually inspect the previous character. This is to ensure that,
212        in partial multi-segment matching, at least one character from the old
213        segment is retained when a new segment is processed. Otherwise, if there
214        are no lookbehinds in the pattern, \A might match incorrectly at the start
215        of a new segment.
216    
217    18. Added some #ifdef __VMS code into pcretest.c to help VMS implementations.
218    
219    19. Redefined some pcre_uchar variables in pcre_exec.c as pcre_uint32; this
220        gives some modest performance improvement in 8-bit mode.
221    
222    20. Added the PCRE-specific property \p{Xuc} for matching characters that can
223        be expressed in certain programming languages using Universal Character
224        Names.
225    
226    21. Unicode validation has been updated in the light of Unicode Corrigendum #9,
227        which points out that "non characters" are not "characters that may not
228        appear in Unicode strings" but rather "characters that are reserved for
229        internal use and have only local meaning".
230    
231    22. When a pattern was compiled with automatic callouts (PCRE_AUTO_CALLOUT) and
232        there was a conditional group that depended on an assertion, if the
233        assertion was false, the callout that immediately followed the alternation
234        in the condition was skipped when pcre_exec() was used for matching.
235    
236    23. Allow an explicit callout to be inserted before an assertion that is the
237        condition for a conditional group, for compatibility with automatic
238        callouts, which always insert a callout at this point.
239    
240    24. In 8.31, (*COMMIT) was confined to within a recursive subpattern. Perl also
241        confines (*SKIP) and (*PRUNE) in the same way, and this has now been done.
242    
243    25. (*PRUNE) is now supported by the JIT compiler.
244    
245    26. Fix infinite loop when /(?<=(*SKIP)ac)a/ is matched against aa.
246    
247    27. Fix the case where there are two or more SKIPs with arguments that may be
248        ignored.
249    
250    28. (*SKIP) is now supported by the JIT compiler.
251    
252    29. (*THEN) is now supported by the JIT compiler.
253    
254    30. Update RunTest with additional test selector options.
255    
256    31. The way PCRE handles backtracking verbs has been changed in two ways.
257    
258        (1) Previously, in something like (*COMMIT)(*SKIP), COMMIT would override
259        SKIP. Now, PCRE acts on whichever backtracking verb is reached first by
260        backtracking. In some cases this makes it more Perl-compatible, but Perl's
261        rather obscure rules do not always do the same thing.
262    
263        (2) Previously, backtracking verbs were confined within assertions. This is
264        no longer the case for positive assertions, except for (*ACCEPT). Again,
265        this sometimes improves Perl compatibility, and sometimes does not.
266    
267    32. A number of tests that were in test 2 because Perl did things differently
268        have been moved to test 1, because either Perl or PCRE has changed, and
269        these tests are now compatible.
270    
271    32. Backtracking control verbs are now handled in the same way in JIT and
272        interpreter.
273    
274    33. An opening parenthesis in a MARK/PRUNE/SKIP/THEN name in a pattern that
275        contained a forward subroutine reference caused a compile error.
276    
277    34. Auto-detect and optimize limited repetitions in JIT.
278    
279    35. Implement PCRE_NEVER_UTF to lock out the use of UTF, in particular,
280        blocking (*UTF) etc.
281    
282    36. In the interpreter, maximizing pattern repetitions for characters and
283        character types now use tail recursion, which reduces stack usage.
284    
285    37. The value of the max lookbehind was not correctly preserved if a compiled
286        and saved regex was reloaded on a host of different endianness.
287    
288    38. Implemented (*LIMIT_MATCH) and (*LIMIT_RECURSION). As part of the extension
289        of the compiled pattern block, expand the flags field from 16 to 32 bits
290        because it was almost full.
291    
292    39. Try madvise first before posix_madvise.
293    
294    40. Change 7 for PCRE 7.9 made it impossible for pcregrep to find empty lines
295        with a pattern such as ^$. It has taken 4 years for anybody to notice! The
296        original change locked out all matches of empty strings. This has been
297        changed so that one match of an empty string per line is recognized.
298        Subsequent searches on the same line (for colouring or for --only-matching,
299        for example) do not recognize empty strings.
300    
301    41. Applied a user patch to fix a number of spelling mistakes in comments.
302    
303    42. Data lines longer than 65536 caused pcretest to crash.
304    
305    43. Clarified the data type for length and startoffset arguments for pcre_exec
306        and pcre_dfa_exec in the function-specific man pages, where they were
307        explicitly stated to be in bytes, never having been updated. I also added
308        some clarification to the pcreapi man page.
309    
310    44. A call to pcre_dfa_exec() with an output vector size less than 2 caused
311        a segmentation fault.
312    
313    
314    Version 8.32 30-November-2012
315    -----------------------------
316    
317    1.  Improved JIT compiler optimizations for first character search and single
318        character iterators.
319    
320    2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
321        Patch by Daniel Richard G.
322    
323    3.  Single character iterator optimizations in the JIT compiler.
324    
325    4.  Improved JIT compiler optimizations for character ranges.
326    
327    5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
328        Reported by Giuseppe D'Angelo.
329    
330    6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
331        of a line, was being set incorrectly in cases where .* appeared inside
332        atomic brackets at the start of a pattern, or where there was a subsequent
333        *PRUNE or *SKIP.
334    
335    7.  Improved instruction cache flush for POWER/PowerPC.
336        Patch by Daniel Richard G.
337    
338    8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
339        grep:
340    
341        (a) There is now no limit to the number of patterns to be matched.
342    
343        (b) An error is given if a pattern is too long.
344    
345        (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
346            are now supported.
347    
348        (d) --exclude-from and --include-from (multiple use) have been added.
349    
350        (e) Exclusions and inclusions now apply to all files and directories, not
351            just to those obtained from scanning a directory recursively.
352    
353        (f) Multiple uses of -f and --file-list are now supported.
354    
355        (g) In a Windows environment, the default for -d has been changed from
356            "read" (the GNU grep default) to "skip", because otherwise the presence
357            of a directory in the file list provokes an error.
358    
359        (h) The documentation has been revised and clarified in places.
360    
361    9.  Improve the matching speed of capturing brackets.
362    
363    10. Changed the meaning of \X so that it now matches a Unicode extended
364        grapheme cluster.
365    
366    11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
367        out POSIX threads when JIT support is configured.
368    
369    12. Added support for PCRE_STUDY_EXTRA_NEEDED.
370    
371    13. In the POSIX wrapper regcomp() function, setting re_nsub field in the preg
372        structure could go wrong in environments where size_t is not the same size
373        as int.
374    
375    14. Applied user-supplied patch to pcrecpp.cc to allow PCRE_NO_UTF8_CHECK to be
376        set.
377    
378    15. The EBCDIC support had decayed; later updates to the code had included
379        explicit references to (e.g.) \x0a instead of CHAR_LF. There has been a
380        general tidy up of EBCDIC-related issues, and the documentation was also
381        not quite right. There is now a test that can be run on ASCII systems to
382        check some of the EBCDIC-related things (but is it not a full test).
383    
384    16. The new PCRE_STUDY_EXTRA_NEEDED option is now used by pcregrep, resulting
385        in a small tidy to the code.
386    
387    17. Fix JIT tests when UTF is disabled and both 8 and 16 bit mode are enabled.
388    
389    18. If the --only-matching (-o) option in pcregrep is specified multiple
390        times, each one causes appropriate output. For example, -o1 -o2 outputs the
391        substrings matched by the 1st and 2nd capturing parentheses. A separating
392        string can be specified by --om-separator (default empty).
393    
394    19. Improving the first n character searches.
395    
396    20. Turn case lists for horizontal and vertical white space into macros so that
397        they are defined only once.
398    
399    21. This set of changes together give more compatible Unicode case-folding
400        behaviour for characters that have more than one other case when UCP
401        support is available.
402    
403        (a) The Unicode property table now has offsets into a new table of sets of
404            three or more characters that are case-equivalent. The MultiStage2.py
405            script that generates these tables (the pcre_ucd.c file) now scans
406            CaseFolding.txt instead of UnicodeData.txt for character case
407            information.
408    
409        (b) The code for adding characters or ranges of characters to a character
410            class has been abstracted into a generalized function that also handles
411            case-independence. In UTF-mode with UCP support, this uses the new data
412            to handle characters with more than one other case.
413    
414        (c) A bug that is fixed as a result of (b) is that codepoints less than 256
415            whose other case is greater than 256 are now correctly matched
416            caselessly. Previously, the high codepoint matched the low one, but not
417            vice versa.
418    
419        (d) The processing of \h, \H, \v, and \ in character classes now makes use
420            of the new class addition function, using character lists defined as
421            macros alongside the case definitions of 20 above.
422    
423        (e) Caseless back references now work with characters that have more than
424            one other case.
425    
426        (f) General caseless matching of characters with more than one other case
427            is supported.
428    
429    22. Unicode character properties were updated from Unicode 6.2.0
430    
431    23. Improved CMake support under Windows. Patch by Daniel Richard G.
432    
433    24. Add support for 32-bit character strings, and UTF-32
434    
435    25. Major JIT compiler update (code refactoring and bugfixing).
436        Experimental Sparc 32 support is added.
437    
438    26. Applied a modified version of Daniel Richard G's patch to create
439        pcre.h.generic and config.h.generic by "make" instead of in the
440        PrepareRelease script.
441    
442    27. Added a definition for CHAR_NULL (helpful for the z/OS port), and use it in
443        pcre_compile.c when checking for a zero character.
444    
445    28. Introducing a native interface for JIT. Through this interface, the compiled
446        machine code can be directly executed. The purpose of this interface is to
447        provide fast pattern matching, so several sanity checks are not performed.
448        However, feature tests are still performed. The new interface provides
449        1.4x speedup compared to the old one.
450    
451    29. If pcre_exec() or pcre_dfa_exec() was called with a negative value for
452        the subject string length, the error given was PCRE_ERROR_BADOFFSET, which
453        was confusing. There is now a new error PCRE_ERROR_BADLENGTH for this case.
454    
455    30. In 8-bit UTF-8 mode, pcretest failed to give an error for data codepoints
456        greater than 0x7fffffff (which cannot be represented in UTF-8, even under
457        the "old" RFC 2279). Instead, it ended up passing a negative length to
458        pcre_exec().
459    
460    31. Add support for GCC's visibility feature to hide internal functions.
461    
462    32. Running "pcretest -C pcre8" or "pcretest -C pcre16" gave a spurious error
463        "unknown -C option" after outputting 0 or 1.
464    
465    33. There is now support for generating a code coverage report for the test
466        suite in environments where gcc is the compiler and lcov is installed. This
467        is mainly for the benefit of the developers.
468    
469    34. If PCRE is built with --enable-valgrind, certain memory regions are marked
470        unaddressable using valgrind annotations, allowing valgrind to detect
471        invalid memory accesses. This is mainly for the benefit of the developers.
472    
473    25. (*UTF) can now be used to start a pattern in any of the three libraries.
474    
475    26. Give configure error if --enable-cpp but no C++ compiler found.
476    
477    
478    Version 8.31 06-July-2012
479    -------------------------
480    
481    1.  Fixing a wrong JIT test case and some compiler warnings.
482    
483    2.  Removed a bashism from the RunTest script.
484    
485    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
486        to unsigned type, result still unsigned" that was given by an MS compiler
487        on encountering the code "-sizeof(xxx)".
488    
489    4.  Partial matching support is added to the JIT compiler.
490    
491    5.  Fixed several bugs concerned with partial matching of items that consist
492        of more than one character:
493    
494        (a) /^(..)\1/ did not partially match "aba" because checking references was
495            done on an "all or nothing" basis. This also applied to repeated
496            references.
497    
498        (b) \R did not give a hard partial match if \r was found at the end of the
499            subject.
500    
501        (c) \X did not give a hard partial match after matching one or more
502            characters at the end of the subject.
503    
504        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
505            a partial match for the string "\r".
506    
507        (e) When newline was set to CRLF, the metacharacter "." did not recognize
508            a partial match for a CR character at the end of the subject string.
509    
510    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
511        running pcretest, the text "(JIT)" added to the output whenever JIT is
512        actually used to run the match.
513    
514    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
515        or /S+[+] with a digit between 1 and 7.
516    
517    8.  OP_NOT now supports any UTF character not just single-byte ones.
518    
519    9.  (*MARK) control verb is now supported by the JIT compiler.
520    
521    10. The command "./RunTest list" lists the available tests without actually
522        running any of them. (Because I keep forgetting what they all are.)
523    
524    11. Add PCRE_INFO_MAXLOOKBEHIND.
525    
526    12. Applied a (slightly modified) user-supplied patch that improves performance
527        when the heap is used for recursion (compiled with --disable-stack-for-
528        recursion). Instead of malloc and free for each heap frame each time a
529        logical recursion happens, frames are retained on a chain and re-used where
530        possible. This sometimes gives as much as 30% improvement.
531    
532    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
533        call.
534    
535    14. As documented, (*COMMIT) is now confined to within a positive assertion.
536    
537    15. It is now possible to link pcretest with libedit as an alternative to
538        libreadline.
539    
540    16. (*COMMIT) control verb is now supported by the JIT compiler.
541    
542    17. The Unicode data tables have been updated to Unicode 6.1.0.
543    
544    18. Added --file-list option to pcregrep.
545    
546    19. Added binary file support to pcregrep, including the -a, --binary-files,
547        -I, and --text options.
548    
549    20. The madvise function is renamed for posix_madvise for QNX compatibility
550        reasons. Fixed by Giuseppe D'Angelo.
551    
552    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
553    
554    22. Changed the option for creating symbolic links for 16-bit man pages from
555        -s to -sf so that re-installing does not cause issues.
556    
557    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
558    
559    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
560        matches in certain environments (the workspace was not being correctly
561        retained). Also added to pcre_dfa_exec() a simple plausibility check on
562        some of the workspace data at the beginning of a restart.
563    
564    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
565        was not doing so when it should - probably a typo introduced by SVN 528
566        (change 8.10/14).
567    
568    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
569        \w+ when the character tables indicated that \x{c4} was a word character.
570        There were several related cases, all because the tests for doing a table
571        lookup were testing for characters less than 127 instead of 255.
572    
573    27. If a pattern contains capturing parentheses that are not used in a match,
574        their slots in the ovector are set to -1. For those that are higher than
575        any matched groups, this happens at the end of processing. In the case when
576        there were back references that the ovector was too small to contain
577        (causing temporary malloc'd memory to be used during matching), and the
578        highest capturing number was not used, memory off the end of the ovector
579        was incorrectly being set to -1. (It was using the size of the temporary
580        memory instead of the true size.)
581    
582    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
583        ovector size, it uses memory at the end of the block that it has got.
584    
585    29. Check for an overlong MARK name and give an error at compile time. The
586        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
587    
588    30. JIT compiler update.
589    
590    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
591        Rill for the patch.
592    
593    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
594    
595    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
596    
597    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
598        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
599        was enabled.
600    
601    35. Improve JIT code generation for greedy plus quantifier.
602    
603    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
604        1 to "aa" instead of to an empty string. The bug affected repeated groups
605        that could potentially match an empty string.
606    
607    37. Optimizing single character iterators in JIT.
608    
609    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
610        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
611        codepoints that are too big for the mode are faulted, and in a UTF mode,
612        disallowed codepoints are also faulted.
613    
614    39. If PCRE was compiled with UTF support, in three places in the DFA
615        matcher there was code that should only have been obeyed in UTF mode, but
616        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
617        processing when bytes with values greater than 127 were present. In 16-bit
618        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
619        both cases the values are those that cannot be the first data item in a UTF
620        character. The three items that might have provoked this were recursions,
621        possessively repeated groups, and atomic groups.
622    
623    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
624        and pcregrep, because some OS require shared objects to be explicitly
625        passed to ld, causing the link step to fail if they are not.
626    
627    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
628        mode, patterns that started with \h* or \R* might be incorrectly matched.
629    
630    
631    Version 8.30 04-February-2012
632    -----------------------------
633    
634    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
635        name is defined in ctype.h.
636    
637    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
638        only in quite long subpatterns.
639    
640    3.  Removed the function pcre_info(), which has been obsolete and deprecated
641        since it was replaced by pcre_fullinfo() in February 2000.
642    
643    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
644        match a (*MARK), and the match failed at the start of the subject, a
645        reference to memory before the start of the subject could occur. This bug
646        was introduced by fix 17 of release 8.21.
647    
648    5.  A reference to an unset group with zero minimum repetition was giving
649        totally wrong answers (in non-JavaScript-compatibility mode). For example,
650        /(another)?(\1?)test/ matched against "hello world test". This bug was
651        introduced in release 8.13.
652    
653    6.  Add support for 16-bit character strings (a large amount of work involving
654        many changes and refactorings).
655    
656    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
657        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
658        from a file.
659    
660    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
661        rounding is not applied in this particular case).
662    
663    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
664        if they appear, or are escaped, in patterns.
665    
666    10. Get rid of a number of -Wunused-but-set-variable warnings.
667    
668    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
669        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
670        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
671        also returns the mark "x". This bug applied to capturing parentheses,
672        non-capturing parentheses, and atomic parentheses. It also applied to some
673        assertions.
674    
675    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
676        information out of configure.ac instead of relying on pcre.h.generic, which
677        is not stored in the repository.
678    
679    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
680        -lreadline.
681    
682    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
683    
684    15. Applied Graycode's patch to put the top-level frame on the stack rather
685        than the heap when not using the stack for recursion. This gives a
686        performance improvement in many cases when recursion is not deep.
687    
688    16. Experimental code added to "pcretest -C" to output the stack frame size.
689    
690    
691    Version 8.21 12-Dec-2011
692    ------------------------
693    
694    1.  Updating the JIT compiler.
695    
696    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
697        are added as well.
698    
699    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
700        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
701        calling _pcre_jit_exec. Some extra comments are added.
702    
703    4.  (*MARK) settings inside atomic groups that do not contain any capturing
704        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
705        was introduced by change 18 for 8.20.
706    
707    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
708        ECMA-262 standard.
709    
710    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
711        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
712        This bug was probably introduced by change 9 of 8.13.
713    
714    7.  While fixing 6 above, I noticed that a number of other items were being
715        incorrectly rejected as "not fixed length". This arose partly because newer
716        opcodes had not been added to the fixed-length checking code. I have (a)
717        corrected the bug and added tests for these items, and (b) arranged for an
718        error to occur if an unknown opcode is encountered while checking for fixed
719        length instead of just assuming "not fixed length". The items that were
720        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
721        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
722        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
723    
724    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
725        being incorrectly compiled and would have given unpredicatble results.
726    
727    9.  A possessively repeated subpattern with minimum repeat count greater than
728        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
729        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
730        the first (A) could occur when it should not.
731    
732    10. Add a cast and remove a redundant test from the code.
733    
734    11. JIT should use pcre_malloc/pcre_free for allocation.
735    
736    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
737        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
738        is anything other than /usr, -L is still shown).
739    
740    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
741    
742    14. Perl does not support \N without a following name in a [] class; PCRE now
743        also gives an error.
744    
745    15. If a forward reference was repeated with an upper limit of around 2000,
746        it caused the error "internal error: overran compiling workspace". The
747        maximum number of forward references (including repeats) was limited by the
748        internal workspace, and dependent on the LINK_SIZE. The code has been
749        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
750        the default depends on LINK_SIZE. There is a new upper limit (for safety)
751        of around 200,000 forward references. While doing this, I also speeded up
752        the filling in of repeated forward references.
753    
754    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
755        incorrectly expecting the subject to contain another "a" after the start.
756    
757    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
758        in the match, the SKIP should be ignored. This was not happening; instead
759        the SKIP was being treated as NOMATCH. For patterns such as
760        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
761        tested.
762    
763    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
764        now much more compatible with Perl, in particular in cases where the result
765        is a non-match for a non-anchored pattern. For example, if
766        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
767        "m", where previously it did not return a name. A side effect of this
768        change is that for partial matches, the last encountered mark name is
769        returned, as for non matches. A number of tests that were previously not
770        Perl-compatible have been moved into the Perl-compatible test files. The
771        refactoring has had the pleasing side effect of removing one argument from
772        the match() function, thus reducing its stack requirements.
773    
774    19. If the /S+ option was used in pcretest to study a pattern using JIT,
775        subsequent uses of /S (without +) incorrectly behaved like /S+.
776    
777    21. Retrieve executable code size support for the JIT compiler and fixing
778        some warnings.
779    
780    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
781        not work when the shorter character appeared right at the end of the
782        subject string.
783    
784    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
785        systems.
786    
787    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
788        output it when the /M option is used in pcretest.
789    
790    25. The CheckMan script was not being included in the distribution. Also, added
791        an explicit "perl" to run Perl scripts from the PrepareRelease script
792        because this is reportedly needed in Windows.
793    
794    26. If study data was being save in a file and studying had not found a set of
795        "starts with" bytes for the pattern, the data written to the file (though
796        never used) was taken from uninitialized memory and so caused valgrind to
797        complain.
798    
799    27. Updated RunTest.bat as provided by Sheri Pierce.
800    
801    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
802    
803    29. Computation of memory usage for the table of capturing group names was
804        giving an unnecessarily large value.
805    
806    
807    Version 8.20 21-Oct-2011
808    ------------------------
809    
810    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
811        a POSIX class. After further experiments with Perl, which convinced me that
812        Perl has bugs and confusions, a closing square bracket is no longer allowed
813        in a POSIX name. This bug also affected patterns with classes that started
814        with full stops.
815    
816    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
817        captured substring, but while checking the failing first alternative,
818        substring 1 is temporarily captured. If the output vector supplied to
819        pcre_exec() was not big enough for this capture, the yield of the function
820        was still zero ("insufficient space for captured substrings"). This cannot
821        be totally fixed without adding another stack variable, which seems a lot
822        of expense for a edge case. However, I have improved the situation in cases
823        such as /(a)(b)x|abc/ matched against "abc", where the return code
824        indicates that fewer than the maximum number of slots in the ovector have
825        been set.
826    
827    3.  Related to (2) above: when there are more back references in a pattern than
828        slots in the output vector, pcre_exec() uses temporary memory during
829        matching, and copies in the captures as far as possible afterwards. It was
830        using the entire output vector, but this conflicts with the specification
831        that only 2/3 is used for passing back captured substrings. Now it uses
832        only the first 2/3, for compatibility. This is, of course, another edge
833        case.
834    
835    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
836        main code base, and can be used by building with --enable-jit. When this is
837        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
838        runtime --no-jit option is given.
839    
840    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
841        ovector, the return from the function was zero, implying that there were
842        other matches that did not fit. The correct "exactly full" value is now
843        returned.
844    
845    6.  If a subpattern that was called recursively or as a subroutine contained
846        (*PRUNE) or any other control that caused it to give a non-standard return,
847        invalid errors such as "Error -26 (nested recursion at the same subject
848        position)" or even infinite loops could occur.
849    
850    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
851        computing the minimum length on reaching *ACCEPT, and so ended up with the
852        wrong value of 1 rather than 0. Further investigation indicates that
853        computing a minimum subject length in the presence of *ACCEPT is difficult
854        (think back references, subroutine calls), and so I have changed the code
855        so that no minimum is registered for a pattern that contains *ACCEPT.
856    
857    8.  If (*THEN) was present in the first (true) branch of a conditional group,
858        it was not handled as intended. [But see 16 below.]
859    
860    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
861        Sheri Pierce.
862    
863    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
864        the first byte in a match must be "a".
865    
866    11. Change 17 for 8.13 increased the recursion depth for patterns like
867        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
868        pattern contains any instances of (*THEN). If it does not, the old
869        optimizations are restored. It would be nice to do this on a per-group
870        basis, but at the moment that is not feasible.
871    
872    12. In some environments, the output of pcretest -C is CRLF terminated. This
873        broke RunTest's code that checks for the link size. A single white space
874        character after the value is now allowed for.
875    
876    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
877        For "fr", it uses the Windows-specific input and output files.
878    
879    14. If (*THEN) appeared in a group that was called recursively or as a
880        subroutine, it did not work as intended. [But see next item.]
881    
882    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
883        pattern fragments (but not containing any | characters). If A and B are
884        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
885        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
886        D. In other words, Perl considers parentheses that do not contain any |
887        characters to be part of a surrounding alternative, whereas PCRE was
888        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
889        differently. PCRE now behaves in the same way as Perl, except in the case
890        of subroutine/recursion calls such as (?1) which have in any case always
891        been different (but PCRE had them first :-).
892    
893    16. Related to 15 above: Perl does not treat the | in a conditional group as
894        creating alternatives. Such a group is treated in the same way as an
895        ordinary group without any | characters when processing (*THEN). PCRE has
896        been changed to match Perl's behaviour.
897    
898    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
899        RunGrepTest script failed.
900    
901    18. Change 22 for version 13 caused atomic groups to use more stack. This is
902        inevitable for groups that contain captures, but it can lead to a lot of
903        stack use in large patterns. The old behaviour has been restored for atomic
904        groups that do not contain any capturing parentheses.
905    
906    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
907        suppress the check for a minimum subject length at run time. (If it was
908        given to pcre_exec() or pcre_dfa_exec() it did work.)
909    
910    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
911        fail to work when decoding hex characters in data strings in EBCDIC
912        environments.
913    
914    21. It appears that in at least one Mac OS environment, the isxdigit() function
915        is implemented as a macro that evaluates to its argument more than once,
916        contravening the C 90 Standard (I haven't checked a later standard). There
917        was an instance in pcretest which caused it to go wrong when processing
918        \x{...} escapes in subject strings. The has been rewritten to avoid using
919        things like p++ in the argument of isxdigit().
920    
921    
922    Version 8.13 16-Aug-2011
923    ------------------------
924    
925    1.  The Unicode data tables have been updated to Unicode 6.0.0.
926    
927    2.  Two minor typos in pcre_internal.h have been fixed.
928    
929    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
930        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
931        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
932    
933    4.  There were a number of related bugs in the code for matching backrefences
934        caselessly in UTF-8 mode when codes for the characters concerned were
935        different numbers of bytes. For example, U+023A and U+2C65 are an upper
936        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
937        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
938        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
939        2-byte code at the end of the subject (it thought there wasn't enough data
940        left).
941    
942    5.  Comprehensive information about what went wrong is now returned by
943        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
944        as the output vector has at least 2 elements. The offset of the start of
945        the failing character and a reason code are placed in the vector.
946    
947    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
948        now returned is for the first byte of the failing character, instead of the
949        last byte inspected. This is an incompatible change, but I hope it is small
950        enough not to be a problem. It makes the returned offset consistent with
951        pcre_exec() and pcre_dfa_exec().
952    
953    7.  pcretest now gives a text phrase as well as the error number when
954        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
955        failure, the offset and reason code are output.
956    
957    8.  When \R was used with a maximizing quantifier it failed to skip backwards
958        over a \r\n pair if the subsequent match failed. Instead, it just skipped
959        back over a single character (\n). This seems wrong (because it treated the
960        two characters as a single entity when going forwards), conflicts with the
961        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
962        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
963        has been changed.
964    
965    9.  Some internal refactoring has changed the processing so that the handling
966        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
967        time (the PCRE_DOTALL option was changed this way some time ago: version
968        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
969        which was always a bit of a fudge. It also means that there is one less
970        argument for the match() function, which reduces its stack requirements
971        slightly. This change also fixes an incompatibility with Perl: the pattern
972        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
973    
974    10. More internal refactoring has drastically reduced the number of recursive
975        calls to match() for possessively repeated groups such as (abc)++ when
976        using pcre_exec().
977    
978    11. While implementing 10, a number of bugs in the handling of groups were
979        discovered and fixed:
980    
981        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
982        (a|)*(?1) gave a compile-time internal error.
983        ((a|)+)+  did not notice that the outer group could match an empty string.
984        (^a|^)+   was not marked as anchored.
985        (.*a|.*)+ was not marked as matching at start or after a newline.
986    
987    12. Yet more internal refactoring has removed another argument from the match()
988        function. Special calls to this function are now indicated by setting a
989        value in a variable in the "match data" data block.
990    
991    13. Be more explicit in pcre_study() instead of relying on "default" for
992        opcodes that mean there is no starting character; this means that when new
993        ones are added and accidentally left out of pcre_study(), testing should
994        pick them up.
995    
996    14. The -s option of pcretest has been documented for ages as being an old
997        synonym of -m (show memory usage). I have changed it to mean "force study
998        for every regex", that is, assume /S for every regex. This is similar to -i
999        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
1000        using it. It makes it easier to run collections of tests with and without
1001        study enabled, and thereby test pcre_study() more easily. All the standard
1002        tests are now run with and without -s (but some patterns can be marked as
1003        "never study" - see 20 below).
1004    
1005    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
1006        restoration of the capturing data to the outer values was not happening
1007        correctly.
1008    
1009    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
1010        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
1011        pattern had matched an empty string, and so incorrectly returned a no
1012        match.
1013    
1014    17. There was optimizing code for the last branch of non-capturing parentheses,
1015        and also for the obeyed branch of a conditional subexpression, which used
1016        tail recursion to cut down on stack usage. Unfortunately, now that there is
1017        the possibility of (*THEN) occurring in these branches, tail recursion is
1018        no longer possible because the return has to be checked for (*THEN). These
1019        two optimizations have therefore been removed. [But see 8.20/11 above.]
1020    
1021    18. If a pattern containing \R was studied, it was assumed that \R always
1022        matched two bytes, thus causing the minimum subject length to be
1023        incorrectly computed because \R can also match just one byte.
1024    
1025    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
1026        was incorrectly computed.
1027    
1028    20. If /S is present twice on a test pattern in pcretest input, it now
1029        *disables* studying, thereby overriding the use of -s on the command line
1030        (see 14 above). This is necessary for one or two tests to keep the output
1031        identical in both cases.
1032    
1033    21. When (*ACCEPT) was used in an assertion that matched an empty string and
1034        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
1035    
1036    22. When an atomic group that contained a capturing parenthesis was
1037        successfully matched, but the branch in which it appeared failed, the
1038        capturing was not being forgotten if a higher numbered group was later
1039        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
1040        group 1 to "a", when in fact it should be unset. This applied to multi-
1041        branched capturing and non-capturing groups, repeated or not, and also to
1042        positive assertions (capturing in negative assertions does not happen
1043        in PCRE) and also to nested atomic groups.
1044    
1045    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
1046        subject after a captured substring, to make it easier to tell which of a
1047        number of identical substrings has been captured.
1048    
1049    24. The way atomic groups are processed by pcre_exec() has been changed so that
1050        if they are repeated, backtracking one repetition now resets captured
1051        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
1052        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
1053        "aaa". Previously, it would have been "a". As part of this code
1054        refactoring, the way recursive calls are handled has also been changed.
1055    
1056    25. If an assertion condition captured any substrings, they were not passed
1057        back unless some other capturing happened later. For example, if
1058        (?(?=(a))a) was matched against "a", no capturing was returned.
1059    
1060    26. When studying a pattern that contained subroutine calls or assertions,
1061        the code for finding the minimum length of a possible match was handling
1062        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
1063        group 1 called group 2 while simultaneously a separate group 2 called group
1064        1). A stack overflow occurred in this case. I have fixed this by limiting
1065        the recursion depth to 10.
1066    
1067    27. Updated RunTest.bat in the distribution to the version supplied by Tom
1068        Fortmann. This supports explicit test numbers on the command line, and has
1069        argument validation and error reporting.
1070    
1071    28. An instance of \X with an unlimited repeat could fail if at any point the
1072        first character it looked at was a mark character.
1073    
1074    29. Some minor code refactoring concerning Unicode properties and scripts
1075        should reduce the stack requirement of match() slightly.
1076    
1077    30. Added the '=' option to pcretest to check the setting of unused capturing
1078        slots at the end of the pattern, which are documented as being -1, but are
1079        not included in the return count.
1080    
1081    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
1082        compiled something random. Now it gives a compile-time error (as does
1083        Perl).
1084    
1085    32. A *MARK encountered during the processing of a positive assertion is now
1086        recorded and passed back (compatible with Perl).
1087    
1088    33. If --only-matching or --colour was set on a pcregrep call whose pattern
1089        had alternative anchored branches, the search for a second match in a line
1090        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
1091        matched the line "0102" twice. The same bug affected patterns that started
1092        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
1093        twice.
1094    
1095    34. Previously, PCRE did not allow quantification of assertions. However, Perl
1096        does, and because of capturing effects, quantifying parenthesized
1097        assertions may at times be useful. Quantifiers are now allowed for
1098        parenthesized assertions.
1099    
1100    35. A minor code tidy in pcre_compile() when checking options for \R usage.
1101    
1102    36. \g was being checked for fancy things in a character class, when it should
1103        just be a literal "g".
1104    
1105    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
1106        appearance of a nested POSIX class supersedes an apparent external class.
1107        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
1108        unescaped square brackets may also appear as part of class names. For
1109        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
1110        more like Perl. (But see 8.20/1 above.)
1111    
1112    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
1113        was because it thought it was \N{name}, which is not supported).
1114    
1115    39. Add minix to OS list not supporting the -S option in pcretest.
1116    
1117    40. PCRE tries to detect cases of infinite recursion at compile time, but it
1118        cannot analyze patterns in sufficient detail to catch mutual recursions
1119        such as ((?1))((?2)). There is now a runtime test that gives an error if a
1120        subgroup is called recursively as a subpattern for a second time at the
1121        same position in the subject string. In previous releases this might have
1122        been caught by the recursion limit, or it might have run out of stack.
1123    
1124    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
1125        happen only once. PCRE was, however incorrectly giving a compile time error
1126        "recursive call could loop indefinitely" because it cannot analyze the
1127        pattern in sufficient detail. The compile time test no longer happens when
1128        PCRE is compiling a conditional subpattern, but actual runaway loops are
1129        now caught at runtime (see 40 above).
1130    
1131    42. It seems that Perl allows any characters other than a closing parenthesis
1132        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
1133        has been changed to be the same.
1134    
1135    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
1136        as not to get warnings when autogen.sh is called. Also changed
1137        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
1138    
1139    44. To help people who use pcregrep to scan files containing exceedingly long
1140        lines, the following changes have been made:
1141    
1142        (a) The default value of the buffer size parameter has been increased from
1143            8K to 20K. (The actual buffer used is three times this size.)
1144    
1145        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
1146            PCRE is built.
1147    
1148        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
1149            to be set at run time.
1150    
1151        (d) Numerical values in pcregrep options can be followed by K or M, for
1152            example --buffer-size=50K.
1153    
1154        (e) If a line being scanned overflows pcregrep's buffer, an error is now
1155            given and the return code is set to 2.
1156    
1157    45. Add a pointer to the latest mark to the callout data block.
1158    
1159    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
1160        partial match of an empty string instead of no match. This was specific to
1161        the use of ".".
1162    
1163    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
1164        complete match instead of a partial match. This bug was dependent on both
1165        the PCRE_UTF8 and PCRE_DOTALL options being set.
1166    
1167    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
1168        starting byte set, because \b was not being ignored.
1169    
1170    
1171    Version 8.12 15-Jan-2011
1172    ------------------------
1173    
1174    1.  Fixed some typos in the markup of the man pages, and wrote a script that
1175        checks for such things as part of the documentation building process.
1176    
1177    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
1178        --match-limit and --recursion-limit options (added for 8.11). In
1179        particular, this made one of the standard tests fail. (The integer value
1180        went into the wrong half of a long int.)
1181    
1182    3.  If the --colour option was given to pcregrep with -v (invert match), it
1183        did strange things, either producing crazy output, or crashing. It should,
1184        of course, ignore a request for colour when reporting lines that do not
1185        match.
1186    
1187    4.  Another pcregrep bug caused similar problems if --colour was specified with
1188        -M (multiline) and the pattern match finished with a line ending.
1189    
1190    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
1191        matched in multiline mode, the following line was shown as part of the
1192        match. This seems wrong, so I have changed it.
1193    
1194    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
1195        the check for further matches in the same line (so they could be coloured)
1196        to overrun the end of the current line. If another match was found, it was
1197        incorrectly shown (and then shown again when found in the next line).
1198    
1199    7.  If pcregrep was compiled under Windows, there was a reference to the
1200        function pcregrep_exit() before it was defined. I am assuming this was
1201        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
1202        reported by a user. I've moved the definition above the reference.
1203    
1204    
1205    Version 8.11 10-Dec-2010
1206    ------------------------
1207    
1208    1.  (*THEN) was not working properly if there were untried alternatives prior
1209        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
1210        backtracked to try for "b" instead of moving to the next alternative branch
1211        at the same level (in this case, to look for "c"). The Perl documentation
1212        is clear that when (*THEN) is backtracked onto, it goes to the "next
1213        alternative in the innermost enclosing group".
1214    
1215    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
1216        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
1217        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
1218        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
1219        (*THEN).
1220    
1221    3.  If \s appeared in a character class, it removed the VT character from
1222        the class, even if it had been included by some previous item, for example
1223        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
1224        of \s, but is part of the POSIX "space" class.)
1225    
1226    4.  A partial match never returns an empty string (because you can always
1227        match an empty string at the end of the subject); however the checking for
1228        an empty string was starting at the "start of match" point. This has been
1229        changed to the "earliest inspected character" point, because the returned
1230        data for a partial match starts at this character. This means that, for
1231        example, /(?<=abc)def/ gives a partial match for the subject "abc"
1232        (previously it gave "no match").
1233    
1234    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
1235        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
1236        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
1237        has an implication that the given string is incomplete (because a partial
1238        match is preferred over a full match). For this reason, these items now
1239        give a partial match in this situation. [Aside: previously, the one case
1240        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
1241        match rather than a full match, which was wrong by the old rules, but is
1242        now correct.]
1243    
1244    6.  There was a bug in the handling of #-introduced comments, recognized when
1245        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
1246        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
1247        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
1248        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
1249        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
1250        places in pcre_compile().
1251    
1252    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
1253        comments when looking ahead for named forward references to subpatterns,
1254        the only newline sequence it recognized was NL. It now handles newlines
1255        according to the set newline convention.
1256    
1257    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
1258        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
1259        cater for a lack of strerror(). These oversights have been fixed.
1260    
1261    9.  Added --match-limit and --recursion-limit to pcregrep.
1262    
1263    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
1264    
1265    11. When the -o option was used, pcregrep was setting a return code of 1, even
1266        when matches were found, and --line-buffered was not being honoured.
1267    
1268    12. Added an optional parentheses number to the -o and --only-matching options
1269        of pcregrep.
1270    
1271    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
1272        can match an empty string. The code to do it in pcretest and pcredemo
1273        needed fixing:
1274    
1275        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
1276            only one byte after an empty string match just before CRLF (this case
1277            just got forgotten; "any" and "anycrlf" were OK).
1278    
1279        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
1280            mode when an empty string match preceded an ASCII character followed by
1281            a non-ASCII character. (The code for advancing by one character rather
1282            than one byte was nonsense.)
1283    
1284        (c) The pcredemo.c sample program did not have any code at all to handle
1285            the cases when CRLF is a valid newline sequence.
1286    
1287    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
1288        as a starting offset was within the subject string. There is now a new
1289        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
1290        negative or greater than the length of the string. In order to test this,
1291        pcretest is extended to allow the setting of negative starting offsets.
1292    
1293    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
1294        starting offset points to the beginning of a UTF-8 character was
1295        unnecessarily clumsy. I tidied it up.
1296    
1297    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
1298        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
1299    
1300    17. Nobody had reported that the --include_dir option, which was added in
1301        release 7.7 should have been called --include-dir (hyphen, not underscore)
1302        for compatibility with GNU grep. I have changed it to --include-dir, but
1303        left --include_dir as an undocumented synonym, and the same for
1304        --exclude-dir, though that is not available in GNU grep, at least as of
1305        release 2.5.4.
1306    
1307    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
1308        characters from a string of bytes) have been redefined so as not to use
1309        loops, in order to improve performance in some environments. At the same
1310        time, I abstracted some of the common code into auxiliary macros to save
1311        repetition (this should not affect the compiled code).
1312    
1313    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
1314        compile-time error is now given if \c is not followed by an ASCII
1315        character, that is, a byte less than 128. (In EBCDIC mode, the code is
1316        different, and any byte value is allowed.)
1317    
1318    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
1319        START_OPTIMIZE option, which is now allowed at compile time - but just
1320        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
1321        to pcregrep and other applications that have no direct access to PCRE
1322        options. The new /Y option in pcretest sets this option when calling
1323        pcre_compile().
1324    
1325    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
1326        back references. Groups containing recursive back references were forced to
1327        be atomic by that change, but in the case of named groups, the amount of
1328        memory required was incorrectly computed, leading to "Failed: internal
1329        error: code overflow". This has been fixed.
1330    
1331    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
1332        pcretest.c, to avoid build problems in some Borland environments.
1333    
1334    
1335    Version 8.10 25-Jun-2010
1336    ------------------------
1337    
1338    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
1339        THEN.
1340    
1341    2.  (*ACCEPT) was not working when inside an atomic group.
1342    
1343    3.  Inside a character class, \B is treated as a literal by default, but
1344        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
1345        causes the error). The code is unchanged, but I tidied the documentation.
1346    
1347    4.  Inside a character class, PCRE always treated \R and \X as literals,
1348        whereas Perl faults them if its -w option is set. I have changed PCRE so
1349        that it faults them when PCRE_EXTRA is set.
1350    
1351    5.  Added support for \N, which always matches any character other than
1352        newline. (It is the same as "." when PCRE_DOTALL is not set.)
1353    
1354    6.  When compiling pcregrep with newer versions of gcc which may have
1355        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
1356        declared with attribute warn_unused_result" were given. Just casting the
1357        result to (void) does not stop the warnings; a more elaborate fudge is
1358        needed. I've used a macro to implement this.
1359    
1360    7.  Minor change to pcretest.c to avoid a compiler warning.
1361    
1362    8.  Added four artifical Unicode properties to help with an option to make
1363        \s etc use properties (see next item). The new properties are: Xan
1364        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
1365    
1366    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
1367        use Unicode properties. (*UCP) at the start of a pattern can be used to set
1368        this option. Modified pcretest to add /W to test this facility. Added
1369        REG_UCP to make it available via the POSIX interface.
1370    
1371    10. Added --line-buffered to pcregrep.
1372    
1373    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
1374        studied, and the match started with a letter with a code point greater than
1375        127 whose first byte was different to the first byte of the other case of
1376        the letter, the other case of this starting letter was not recognized
1377        (#976).
1378    
1379    12. If a pattern that was studied started with a repeated Unicode property
1380        test, for example, \p{Nd}+, there was the theoretical possibility of
1381        setting up an incorrect bitmap of starting bytes, but fortunately it could
1382        not have actually happened in practice until change 8 above was made (it
1383        added property types that matched character-matching opcodes).
1384    
1385    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
1386        possible starting bytes for non-anchored patterns.
1387    
1388    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
1389        \R, and also a number of cases that involve Unicode properties, both
1390        explicit and implicit when PCRE_UCP is set.
1391    
1392    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
1393        input, it could crash or give wrong results if characters with values
1394        greater than 0xc0 were present in the subject string. (Detail: it assumed
1395        UTF-8 input when processing these items.)
1396    
1397    16. Added a lot of (int) casts to avoid compiler warnings in systems where
1398        size_t is 64-bit (#991).
1399    
1400    17. Added a check for running out of memory when PCRE is compiled with
1401        --disable-stack-for-recursion (#990).
1402    
1403    18. If the last data line in a file for pcretest does not have a newline on
1404        the end, a newline was missing in the output.
1405    
1406    19. The default pcre_chartables.c file recognizes only ASCII characters (values
1407        less than 128) in its various bitmaps. However, there is a facility for
1408        generating tables according to the current locale when PCRE is compiled. It
1409        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
1410        characters, are recognized by isspace() and therefore were getting set in
1411        these tables, and indeed these tables seem to approximate to ISO 8859. This
1412        caused a problem in UTF-8 mode when pcre_study() was used to create a list
1413        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
1414        which of course cannot start UTF-8 characters. I have changed the code so
1415        that only real ASCII characters (less than 128) and the correct starting
1416        bytes for UTF-8 encodings are set for characters greater than 127 when in
1417        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
1418        altogether.)
1419    
1420    20. Added the /T option to pcretest so as to be able to run tests with non-
1421        standard character tables, thus making it possible to include the tests
1422        used for 19 above in the standard set of tests.
1423    
1424    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
1425        reference to a subpattern the other side of a comment that contains an
1426        opening parenthesis caused either an internal compiling error, or a
1427        reference to the wrong subpattern.
1428    
1429    
1430    Version 8.02 19-Mar-2010
1431    ------------------------
1432    
1433    1.  The Unicode data tables have been updated to Unicode 5.2.0.
1434    
1435    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
1436        configured.
1437    
1438    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
1439        original author of that file, following a query about its status.
1440    
1441    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
1442        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
1443    
1444    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
1445        quantifier applied to a forward-referencing subroutine call, could compile
1446        incorrect code or give the error "internal error: previously-checked
1447        referenced subpattern not found".
1448    
1449    6.  Both MS Visual Studio and Symbian OS have problems with initializing
1450        variables to point to external functions. For these systems, therefore,
1451        pcre_malloc etc. are now initialized to local functions that call the
1452        relevant global functions.
1453    
1454    7.  There were two entries missing in the vectors called coptable and poptable
1455        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
1456        I've fixed the data, and added a kludgy way of testing at compile time that
1457        the lengths are correct (equal to the number of opcodes).
1458    
1459    8.  Following on from 7, I added a similar kludge to check the length of the
1460        eint vector in pcreposix.c.
1461    
1462    9.  Error texts for pcre_compile() are held as one long string to avoid too
1463        much relocation at load time. To find a text, the string is searched,
1464        counting zeros. There was no check for running off the end of the string,
1465        which could happen if a new error number was added without updating the
1466        string.
1467    
1468    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
1469    
1470    11. \K was not working if it appeared in an atomic group or in a group that
1471        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
1472        \K is "not well defined" if used in an assertion. PCRE now accepts it if
1473        the assertion is positive, but not if it is negative.
1474    
1475    12. Change 11 fortuitously reduced the size of the stack frame used in the
1476        "match()" function of pcre_exec.c by one pointer. Forthcoming
1477        implementation of support for (*MARK) will need an extra pointer on the
1478        stack; I have reserved it now, so that the stack frame size does not
1479        decrease.
1480    
1481    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
1482        item in branch that calls a recursion is a subroutine call - as in the
1483        second branch in the above example - was incorrectly given the compile-
1484        time error "recursive call could loop indefinitely" because pcre_compile()
1485        was not correctly checking the subroutine for matching a non-empty string.
1486    
1487    14. The checks for overrunning compiling workspace could trigger after an
1488        overrun had occurred. This is a "should never occur" error, but it can be
1489        triggered by pathological patterns such as hundreds of nested parentheses.
1490        The checks now trigger 100 bytes before the end of the workspace.
1491    
1492    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
1493    
1494    
1495    Version 8.01 19-Jan-2010
1496    ------------------------
1497    
1498    1.  If a pattern contained a conditional subpattern with only one branch (in
1499        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
1500        computed the wrong minimum data length (which is of course zero for such
1501        subpatterns). This could cause incorrect "no match" results.
1502    
1503    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
1504        the pattern is reset in the first branch, pcre_compile() failed with
1505        "internal error: code overflow at offset...". This happened only when
1506        the reset was to the original external option setting. (An optimization
1507        abstracts leading options settings into an external setting, which was the
1508        cause of this.)
1509    
1510    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
1511        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
1512        assertion pattern did not match (meaning that the assertion was true), it
1513        was incorrectly treated as false if the SKIP had been reached during the
1514        matching. This also applied to assertions used as conditions.
1515    
1516    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
1517        assertion subpattern, including such a pattern used as a condition,
1518        unpredictable results occurred, instead of the error return
1519        PCRE_ERROR_DFA_UITEM.
1520    
1521    5.  The C++ GlobalReplace function was not working like Perl for the special
1522        situation when an empty string is matched. It now does the fancy magic
1523        stuff that is necessary.
1524    
1525    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
1526        removed. (These were left over from very, very early versions of PCRE.)
1527    
1528    7.  Some cosmetic changes to the code to make life easier when compiling it
1529        as part of something else:
1530    
1531        (a) Change DEBUG to PCRE_DEBUG.
1532    
1533        (b) In pcre_compile(), rename the member of the "branch_chain" structure
1534            called "current" as "current_branch", to prevent a collision with the
1535            Linux macro when compiled as a kernel module.
1536    
1537        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
1538            prevent a collision with the Linux macro when compiled as a kernel
1539            module.
1540    
1541    8.  In pcre_compile() there are some checks for integer overflows that used to
1542        cast potentially large values to (double). This has been changed to that
1543        when building, a check for int64_t is made, and if it is found, it is used
1544        instead, thus avoiding the use of floating point arithmetic. (There is no
1545        other use of FP in PCRE.) If int64_t is not found, the fallback is to
1546        double.
1547    
1548    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
1549        2005 (difference between two addresses compared to an unsigned value).
1550    
1551    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
1552        custom one, because of the following reported problem in Windows:
1553    
1554          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
1555              under Win32.
1556          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
1557              therefore missing the function definition.
1558          - The compiler thus generates a "C" signature for the test function.
1559          - The linker fails to find the "C" function.
1560          - PCRE fails to configure if asked to do so against libbz2.
1561    
1562    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
1563        messages were output:
1564    
1565          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
1566          rerunning libtoolize, to keep the correct libtool macros in-tree.
1567          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
1568    
1569        I have done both of these things.
1570    
1571    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
1572        most of the time, it *can* run out if it is given a pattern that contains a
1573        runaway infinite recursion. I updated the discussion in the pcrestack man
1574        page.
1575    
1576    13. Now that we have gone to the x.xx style of version numbers, the minor
1577        version may start with zero. Using 08 or 09 is a bad idea because users
1578        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
1579        interpreted as invalid octal numbers. I've updated the previous comment in
1580        configure.ac, and also added a check that gives an error if 08 or 09 are
1581        used.
1582    
1583    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
1584        causing partial matching to fail when the end of the subject matched \W
1585        in a UTF-8 pattern where \W was quantified with a minimum of 3.
1586    
1587    15. There were some discrepancies between the declarations in pcre_internal.h
1588        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
1589        their definitions. The declarations used "const uschar *" and the
1590        definitions used USPTR. Even though USPTR is normally defined as "const
1591        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
1592        reported that: "This difference in casting confuses some C++ compilers, for
1593        example, SunCC recognizes above declarations as different functions and
1594        generates broken code for hbpcre." I have changed the declarations to use
1595        USPTR.
1596    
1597    16. GNU libtool is named differently on some systems. The autogen.sh script now
1598        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
1599        (FreeBSD).
1600    
1601    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
1602        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
1603        comment: "Figure out how to create a longlong from a string: strtoll and
1604        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
1605        instance, but it only takes 2 args instead of 3!"
1606    
1607    18. A subtle bug concerned with back references has been fixed by a change of
1608        specification, with a corresponding code fix. A pattern such as
1609        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
1610        refers, was giving matches when it shouldn't. For example, xa=xaaa would
1611        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
1612        same bug. Such groups have to be quantified to be useful, or contained
1613        inside another quantified group. (If there's no repetition, the reference
1614        can never match.) The problem arises because, having left the group and
1615        moved on to the rest of the pattern, a later failure that backtracks into
1616        the group uses the captured value from the final iteration of the group
1617        rather than the correct earlier one. I have fixed this in PCRE by forcing
1618        any group that contains a reference to itself to be an atomic group; that
1619        is, there cannot be any backtracking into it once it has completed. This is
1620        similar to recursive and subroutine calls.
1621    
1622    
1623    Version 8.00 19-Oct-09
1624    ----------------------
1625    
1626    1.  The table for translating pcre_compile() error codes into POSIX error codes
1627        was out-of-date, and there was no check on the pcre_compile() error code
1628        being within the table. This could lead to an OK return being given in
1629        error.
1630    
1631    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
1632        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
1633        in a Windows environment.
1634    
1635    3.  The pcregrep --count option prints the count for each file even when it is
1636        zero, as does GNU grep. However, pcregrep was also printing all files when
1637        --files-with-matches was added. Now, when both options are given, it prints
1638        counts only for those files that have at least one match. (GNU grep just
1639        prints the file name in this circumstance, but including the count seems
1640        more useful - otherwise, why use --count?) Also ensured that the
1641        combination -clh just lists non-zero counts, with no names.
1642    
1643    4.  The long form of the pcregrep -F option was incorrectly implemented as
1644        --fixed_strings instead of --fixed-strings. This is an incompatible change,
1645        but it seems right to fix it, and I didn't think it was worth preserving
1646        the old behaviour.
1647    
1648    5.  The command line items --regex=pattern and --regexp=pattern were not
1649        recognized by pcregrep, which required --regex pattern or --regexp pattern
1650        (with a space rather than an '='). The man page documented the '=' forms,
1651        which are compatible with GNU grep; these now work.
1652    
1653    6.  No libpcreposix.pc file was created for pkg-config; there was just
1654        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
1655    
1656    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
1657        when UCP support is not needed, by modifying the Python script that
1658        generates it from Unicode data files. This should not matter if the module
1659        is correctly used as a library, but I received one complaint about 50K of
1660        unwanted data. My guess is that the person linked everything into his
1661        program rather than using a library. Anyway, it does no harm.
1662    
1663    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
1664        was a minimum greater than 1 for a wide character in a possessive
1665        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
1666        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
1667        character. Chaos in the form of incorrect output or a compiling loop could
1668        result.
1669    
1670    9.  The restrictions on what a pattern can contain when partial matching is
1671        requested for pcre_exec() have been removed. All patterns can now be
1672        partially matched by this function. In addition, if there are at least two
1673        slots in the offset vector, the offset of the earliest inspected character
1674        for the match and the offset of the end of the subject are set in them when
1675        PCRE_ERROR_PARTIAL is returned.
1676    
1677    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
1678        synonymous with PCRE_PARTIAL, for backwards compatibility, and
1679        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
1680        and may be more useful for multi-segment matching.
1681    
1682    11. Partial matching with pcre_exec() is now more intuitive. A partial match
1683        used to be given if ever the end of the subject was reached; now it is
1684        given only if matching could not proceed because another character was
1685        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
1686        string "Z", which now yields "no match" instead of "partial match". In the
1687        case of pcre_dfa_exec(), "no match" is given if every matching path for the
1688        final character ended with (*FAIL).
1689    
1690    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
1691        if the pattern had a "must contain" character that was already found in the
1692        earlier partial match, unless partial matching was again requested. For
1693        example, with the pattern /dog.(body)?/, the "must contain" character is
1694        "g". If the first part-match was for the string "dog", restarting with
1695        "sbody" failed. This bug has been fixed.
1696    
1697    13. The string returned by pcre_dfa_exec() after a partial match has been
1698        changed so that it starts at the first inspected character rather than the
1699        first character of the match. This makes a difference only if the pattern
1700        starts with a lookbehind assertion or \b or \B (\K is not supported by
1701        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1702        matching functions compatible, and I think it's the right thing to do.
1703    
1704    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1705        so that the demonstration program is easily available in environments where
1706        PCRE has not been installed from source.
1707    
1708    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1709        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1710        library.
1711    
1712    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1713        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1714        is not the first non-POSIX option to be added. Clearly some people find
1715        these options useful.
1716    
1717    17. If a caller to the POSIX matching function regexec() passes a non-zero
1718        value for nmatch with a NULL value for pmatch, the value of
1719        nmatch is forced to zero.
1720    
1721    18. RunGrepTest did not have a test for the availability of the -u option of
1722        the diff command, as RunTest does. It now checks in the same way as
1723        RunTest, and also checks for the -b option.
1724    
1725    19. If an odd number of negated classes containing just a single character
1726        interposed, within parentheses, between a forward reference to a named
1727        subpattern and the definition of the subpattern, compilation crashed with
1728        an internal error, complaining that it could not find the referenced
1729        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1730        [The bug was that it was starting one character too far in when skipping
1731        over the character class, thus treating the ] as data rather than
1732        terminating the class. This meant it could skip too much.]
1733    
1734    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1735        /g option in pcretest when the pattern contains \K, which makes it possible
1736        to have an empty string match not at the start, even when the pattern is
1737        anchored. Updated pcretest and pcredemo to use this option.
1738    
1739    21. If the maximum number of capturing subpatterns in a recursion was greater
1740        than the maximum at the outer level, the higher number was returned, but
1741        with unset values at the outer level. The correct (outer level) value is
1742        now given.
1743    
1744    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1745        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1746        make it do so. The string so far is captured, making this feature
1747        compatible with Perl.
1748    
1749    23. The tests have been re-organized, adding tests 11 and 12, to make it
1750        possible to check the Perl 5.10 features against Perl 5.10.
1751    
1752    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1753        pattern matches a fixed length string. PCRE did not allow this; now it
1754        does. Neither allows recursion.
1755    
1756    25. I finally figured out how to implement a request to provide the minimum
1757        length of subject string that was needed in order to match a given pattern.
1758        (It was back references and recursion that I had previously got hung up
1759        on.) This code has now been added to pcre_study(); it finds a lower bound
1760        to the length of subject needed. It is not necessarily the greatest lower
1761        bound, but using it to avoid searching strings that are too short does give
1762        some useful speed-ups. The value is available to calling programs via
1763        pcre_fullinfo().
1764    
1765    26. While implementing 25, I discovered to my embarrassment that pcretest had
1766        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1767        study optimizations had never been tested with that matching function.
1768        Oops. What is worse, even when it was passed study data, there was a bug in
1769        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1770        were also very few tests of studied patterns with pcre_dfa_exec().
1771    
1772    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1773        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1774        on the other side of the coin, they are no longer allowed to have different
1775        names, because these cannot be distinguished in PCRE, and this has caused
1776        confusion. (This is a difference from Perl.)
1777    
1778    28. When duplicate subpattern names are present (necessarily with different
1779        numbers, as required by 27 above), and a test is made by name in a
1780        conditional pattern, either for a subpattern having been matched, or for
1781        recursion in such a pattern, all the associated numbered subpatterns are
1782        tested, and the overall condition is true if the condition is true for any
1783        one of them. This is the way Perl works, and is also more like the way
1784        testing by number works.
1785    
1786    
1787    Version 7.9 11-Apr-09
1788    ---------------------
1789    
1790    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
1791        (pcretest), all targets were linked against these libraries. This included
1792        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
1793        libraries. This caused unwanted dependencies to be created. This problem
1794        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
1795        pcretest is linked with readline.
1796    
1797    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
1798        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
1799        moved outside it again, because FALSE and TRUE are already defined in AIX,
1800        but BOOL is not.
1801    
1802    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
1803        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
1804    
1805    4.  The pcregrep documentation said spaces were inserted as well as colons (or
1806        hyphens) following file names and line numbers when outputting matching
1807        lines. This is not true; no spaces are inserted. I have also clarified the
1808        wording for the --colour (or --color) option.
1809    
1810    5.  In pcregrep, when --colour was used with -o, the list of matching strings
1811        was not coloured; this is different to GNU grep, so I have changed it to be
1812        the same.
1813    
1814    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
1815        each matching line was coloured. Now it goes on to look for further matches
1816        of any of the test patterns, which is the same behaviour as GNU grep.
1817    
1818    7.  A pattern that could match an empty string could cause pcregrep to loop; it
1819        doesn't make sense to accept an empty string match in pcregrep, so I have
1820        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
1821        seems to be how GNU grep behaves. [But see later change 40 for release
1822        8.33.]
1823    
1824    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
1825        start or after a newline", because the conditional assertion was not being
1826        correctly handled. The rule now is that both the assertion and what follows
1827        in the first alternative must satisfy the test.
1828    
1829    9.  If auto-callout was enabled in a pattern with a conditional group whose
1830        condition was an assertion, PCRE could crash during matching, both with
1831        pcre_exec() and pcre_dfa_exec().
1832    
1833    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
1834        used for matching.
1835    
1836    11. Unicode property support in character classes was not working for
1837        characters (bytes) greater than 127 when not in UTF-8 mode.
1838    
1839    12. Added the -M command line option to pcretest.
1840    
1841    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
1842    
1843    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
1844    
1845    16. Added comments and documentation about mis-use of no_arg in the C++
1846        wrapper.
1847    
1848    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
1849        from Martin Jerabek that uses macro names for all relevant character and
1850        string constants.
1851    
1852    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
1853        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
1854        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
1855        these, but not everybody uses configure.
1856    
1857    19. A conditional group that had only one branch was not being correctly
1858        recognized as an item that could match an empty string. This meant that an
1859        enclosing group might also not be so recognized, causing infinite looping
1860        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
1861        with the subject "ab", where knowledge that the repeated group can match
1862        nothing is needed in order to break the loop.
1863    
1864    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
1865        exec(), but without supplying a callout function, matching went wrong.
1866    
1867    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
1868        leak if the size of the offset vector was greater than 30. When the vector
1869        is smaller, the saved offsets during recursion go onto a local stack
1870        vector, but for larger vectors malloc() is used. It was failing to free
1871        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
1872        error, in fact).
1873    
1874    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
1875        heapframe that is used only when UTF-8 support is enabled. This caused no
1876        problem, but was untidy.
1877    
1878    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
1879        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
1880        included within another project.
1881    
1882    24. Steven Van Ingelgem's patches to add more options to the CMake support,
1883        slightly modified by me:
1884    
1885          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
1886              not building pcregrep.
1887    
1888          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
1889              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
1890    
1891    25. Forward references, both numeric and by name, in patterns that made use of
1892        duplicate group numbers, could behave incorrectly or give incorrect errors,
1893        because when scanning forward to find the reference group, PCRE was not
1894        taking into account the duplicate group numbers. A pattern such as
1895        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
1896    
1897    26. Changed a few more instances of "const unsigned char *" to USPTR, making
1898        the feature of a custom pointer more persuasive (as requested by a user).
1899    
1900    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
1901        pcretest.c, inside #ifndefs, because it seems they are sometimes already
1902        pre-defined.
1903    
1904    28. Added support for (*UTF8) at the start of a pattern.
1905    
1906    29. Arrange for flags added by the "release type" setting in CMake to be shown
1907        in the configuration summary.
1908    
1909    
1910    Version 7.8 05-Sep-08
1911    ---------------------
1912    
1913    1.  Replaced UCP searching code with optimized version as implemented for Ad
1914        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
1915        stage table and inline lookup instead of a function, giving speed ups of 2
1916        to 5 times on some simple patterns that I tested. Permission was given to
1917        distribute the MultiStage2.py script that generates the tables (it's not in
1918        the tarball, but is in the Subversion repository).
1919    
1920    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
1921        scripts.
1922    
1923    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
1924        a group with a zero qualifier. The result of the study could be incorrect,
1925        or the function might crash, depending on the pattern.
1926    
1927    4.  Caseless matching was not working for non-ASCII characters in back
1928        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
1929        It now works when Unicode Property Support is available.
1930    
1931    5.  In pcretest, an escape such as \x{de} in the data was always generating
1932        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
1933        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
1934        truncation.
1935    
1936    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
1937    
1938    7.  Added two (int) casts to pcregrep when printing the difference of two
1939        pointers, in case they are 64-bit values.
1940    
1941    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
1942        test 2 if it fails.
1943    
1944    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
1945        and a #define of that name to empty if it is not externally set. This is to
1946        allow users of MSVC to set it if necessary.
1947    
1948    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
1949        the convenience functions in the pcre_get.c source file.
1950    
1951    11. An option change at the start of a pattern that had top-level alternatives
1952        could cause overwriting and/or a crash. This command provoked a crash in
1953        some environments:
1954    
1955          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
1956    
1957        This potential security problem was recorded as CVE-2008-2371.
1958    
1959    12. For a pattern where the match had to start at the beginning or immediately
1960        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
1961        pcre_dfa_exec() could read past the end of the passed subject if there was
1962        no match. To help with detecting such bugs (e.g. with valgrind), I modified
1963        pcretest so that it places the subject at the end of its malloc-ed buffer.
1964    
1965    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
1966        exec() might read past the end of the data buffer in UTF-8 mode.
1967    
1968    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
1969        the data contained the byte 0x85 as part of a UTF-8 character within its
1970        first line. This applied both to normal and DFA matching.
1971    
1972    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
1973        /^[^d]*?$/8 failed to match "abc".
1974    
1975    16. Added a missing copyright notice to pcrecpp_internal.h.
1976    
1977    17. Make it more clear in the documentation that values returned from
1978        pcre_exec() in ovector are byte offsets, not character counts.
1979    
1980    18. Tidied a few places to stop certain compilers from issuing warnings.
1981    
1982    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
1983        supplied by Stefan Weber. I made a further small update for 7.8 because
1984        there is a change of source arrangements: the pcre_searchfuncs.c module is
1985        replaced by pcre_ucd.c.
1986    
1987    
1988    Version 7.7 07-May-08
1989  ---------------------  ---------------------
1990    
1991  1.  Applied Craig's patch to sort out a long long problem: "If we can't convert  1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
1992      a string to a long long, pretend we don't even have a long long." This is      a string to a long long, pretend we don't even have a long long." This is
1993      done by checking for the strtoq, strtoll, and _strtoi64 functions.      done by checking for the strtoq, strtoll, and _strtoi64 functions.
1994    
1995  2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with  2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
1996      pre-7.6 versions, which defined a global no_arg variable instead of putting      pre-7.6 versions, which defined a global no_arg variable instead of putting
1997      it in the RE class.      it in the RE class. (See also #8 below.)
1998    
1999  3.  Remove a line of dead code, identified by coverity and reported by Nuno  3.  Remove a line of dead code, identified by coverity and reported by Nuno
2000      Lopes.      Lopes.
2001    
2002  4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:  4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
2003    
2004      (1) The include/exclude patterns were being applied to the whole pathnames      (1) The include/exclude patterns were being applied to the whole pathnames
2005          of files, instead of just to the final components.          of files, instead of just to the final components.
2006    
2007      (2) If there was more than one level of directory, the subdirectories were      (2) If there was more than one level of directory, the subdirectories were
2008          skipped unless they satisfied the include/exclude conditions. This is          skipped unless they satisfied the include/exclude conditions. This is
2009          inconsistent with GNU grep (and could even be seen as contrary to the          inconsistent with GNU grep (and could even be seen as contrary to the
2010          pcregrep specification - which I improved to make it absolutely clear).          pcregrep specification - which I improved to make it absolutely clear).
2011          The action now is always to scan all levels of directory, and just          The action now is always to scan all levels of directory, and just
2012          apply the include/exclude patterns to regular files.          apply the include/exclude patterns to regular files.
2013    
2014  5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used  5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
2015      --exclude_dir in the tests to avoid scanning .svn directories.      --exclude_dir in the tests to avoid scanning .svn directories.
2016    
2017    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
2018        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
2019        doesn't support NULs in patterns.
2020    
2021    7.  Added some missing "const"s to declarations of static tables in
2022        pcre_compile.c and pcre_dfa_exec.c.
2023    
2024    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
2025        caused by fix #2  above. (Subsequently also a second patch to fix the
2026        first patch. And a third patch - this was a messy problem.)
2027    
2028    9.  Applied Craig's patch to remove the use of push_back().
2029    
2030    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
2031        matching function regexec().
2032    
2033    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
2034        which, however, unlike Perl's \g{...}, are subroutine calls, not back
2035        references. PCRE supports relative numbers with this syntax (I don't think
2036        Oniguruma does).
2037    
2038    12. Previously, a group with a zero repeat such as (...){0} was completely
2039        omitted from the compiled regex. However, this means that if the group
2040        was called as a subroutine from elsewhere in the pattern, things went wrong
2041        (an internal error was given). Such groups are now left in the compiled
2042        pattern, with a new opcode that causes them to be skipped at execution
2043        time.
2044    
2045    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
2046        to the way PCRE behaves:
2047    
2048        (a) A lone ] character is dis-allowed (Perl treats it as data).
2049    
2050        (b) A back reference to an unmatched subpattern matches an empty string
2051            (Perl fails the current match path).
2052    
2053        (c) A data ] in a character class must be notated as \] because if the
2054            first data character in a class is ], it defines an empty class. (In
2055            Perl it is not possible to have an empty class.) The empty class []
2056            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
2057            The negative empty class [^] matches any one character, independently
2058            of the DOTALL setting.
2059    
2060    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
2061        non-existent subpattern following a character class starting with ']' and
2062        containing () gave an internal compiling error instead of "reference to
2063        non-existent subpattern". Fortunately, when the pattern did exist, the
2064        compiled code was correct. (When scanning forwards to check for the
2065        existence of the subpattern, it was treating the data ']' as terminating
2066        the class, so got the count wrong. When actually compiling, the reference
2067        was subsequently set up correctly.)
2068    
2069    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
2070        it was being rejected as not supported by pcre_dfa_exec(), even though
2071        other assertions are supported. I have made pcre_dfa_exec() support
2072        (*FAIL).
2073    
2074    16. The implementation of 13c above involved the invention of a new opcode,
2075        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
2076        cannot be changed at match time, I realized I could make a small
2077        improvement to matching performance by compiling OP_ALLANY instead of
2078        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
2079        on the OP_ANY path.
2080    
2081    17. Compiling pcretest on Windows with readline support failed without the
2082        following two fixes: (1) Make the unistd.h include conditional on
2083        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
2084    
2085    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
2086        ncurses library to be included for pcretest when ReadLine support is
2087        requested, but also to allow for it to be overridden. This patch came from
2088        Daniel Bergström.
2089    
2090    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
2091        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
2092        any errors with the current Unicode tables. Thanks to Peter Kankowski for
2093        spotting this.
2094    
2095    
2096  Version 7.6 28-Jan-08  Version 7.6 28-Jan-08

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