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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.7 05-Mar-08  Version 8.31
5    -----------------------------
6    
7    1.  Fixing a wrong JIT test case and some compiler warnings.
8    
9    2.  Removed a bashism from the RunTest script.
10    
11    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
12        to unsigned type, result still unsigned" that was given by an MS compiler
13        on encountering the code "-sizeof(xxx)".
14    
15    4.  Partial matching support is added to the JIT compiler.
16    
17    5.  Fixed several bugs concerned with partial matching of items that consist
18        of more than one character:
19    
20        (a) /^(..)\1/ did not partially match "aba" because checking references was
21            done on an "all or nothing" basis. This also applied to repeated
22            references.
23    
24        (b) \R did not give a hard partial match if \r was found at the end of the
25            subject.
26    
27        (c) \X did not give a hard partial match after matching one or more
28            characters at the end of the subject.
29    
30        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
31            a partial match for the string "\r".
32    
33        (e) When newline was set to CRLF, the metacharacter "." did not recognize
34            a partial match for a CR character at the end of the subject string.
35    
36    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
37        running pcretest, the text "(JIT)" added to the output whenever JIT is
38        actually used to run the match.
39    
40    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
41        or /S+[+] with a digit between 1 and 7.
42    
43    8.  OP_NOT now supports any UTF character not just single-byte ones.
44    
45    9.  (*MARK) control verb is now supported by the JIT compiler.
46    
47    10. The command "./RunTest list" lists the available tests without actually
48        running any of them. (Because I keep forgetting what they all are.)
49    
50    11. Add PCRE_INFO_MAXLOOKBEHIND.
51    
52    12. Applied a (slightly modified) user-supplied patch that improves performance
53        when the heap is used for recursion (compiled with --disable-stack-for-
54        recursion). Instead of malloc and free for each heap frame each time a
55        logical recursion happens, frames are retained on a chain and re-used where
56        possible. This sometimes gives as much as 30% improvement.
57    
58    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
59        call.
60    
61    14. As documented, (*COMMIT) is now confined to within a positive assertion.
62    
63    15. It is now possible to link pcretest with libedit as an alternative to
64        libreadline.
65    
66    16. (*COMMIT) control verb is now supported by the JIT compiler.
67    
68    17. The Unicode data tables have been updated to Unicode 6.1.0.
69    
70    18. Added --file-list option to pcregrep.
71    
72    19. Added binary file support to pcregrep, including the -a, --binary-files,
73        -I, and --text options.
74    
75    20. The madvise function is renamed for posix_madvise for QNX compatibility
76        reasons. Fixed by Giuseppe D'Angelo.
77    
78    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
79    
80    
81    Version 8.30 04-February-2012
82    -----------------------------
83    
84    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
85        name is defined in ctype.h.
86    
87    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
88        only in quite long subpatterns.
89    
90    3.  Removed the function pcre_info(), which has been obsolete and deprecated
91        since it was replaced by pcre_fullinfo() in February 2000.
92    
93    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
94        match a (*MARK), and the match failed at the start of the subject, a
95        reference to memory before the start of the subject could occur. This bug
96        was introduced by fix 17 of release 8.21.
97    
98    5.  A reference to an unset group with zero minimum repetition was giving
99        totally wrong answers (in non-JavaScript-compatibility mode). For example,
100        /(another)?(\1?)test/ matched against "hello world test". This bug was
101        introduced in release 8.13.
102    
103    6.  Add support for 16-bit character strings (a large amount of work involving
104        many changes and refactorings).
105    
106    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
107        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
108        from a file.
109    
110    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
111        rounding is not applied in this particular case).
112    
113    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
114        if they appear, or are escaped, in patterns.
115    
116    10. Get rid of a number of -Wunused-but-set-variable warnings.
117    
118    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
119        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
120        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
121        also returns the mark "x". This bug applied to capturing parentheses,
122        non-capturing parentheses, and atomic parentheses. It also applied to some
123        assertions.
124    
125    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
126        information out of configure.ac instead of relying on pcre.h.generic, which
127        is not stored in the repository.
128    
129    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
130        -lreadline.
131    
132    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
133    
134    15. Applied Graycode's patch to put the top-level frame on the stack rather
135        than the heap when not using the stack for recursion. This gives a
136        performance improvement in many cases when recursion is not deep.
137    
138    16. Experimental code added to "pcretest -C" to output the stack frame size.
139    
140    
141    Version 8.21 12-Dec-2011
142    ------------------------
143    
144    1.  Updating the JIT compiler.
145    
146    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
147        are added as well.
148    
149    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
150        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
151        calling _pcre_jit_exec. Some extra comments are added.
152    
153    4.  (*MARK) settings inside atomic groups that do not contain any capturing
154        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
155        was introduced by change 18 for 8.20.
156    
157    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
158        ECMA-262 standard.
159    
160    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
161        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
162        This bug was probably introduced by change 9 of 8.13.
163    
164    7.  While fixing 6 above, I noticed that a number of other items were being
165        incorrectly rejected as "not fixed length". This arose partly because newer
166        opcodes had not been added to the fixed-length checking code. I have (a)
167        corrected the bug and added tests for these items, and (b) arranged for an
168        error to occur if an unknown opcode is encountered while checking for fixed
169        length instead of just assuming "not fixed length". The items that were
170        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
171        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
172        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
173    
174    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
175        being incorrectly compiled and would have given unpredicatble results.
176    
177    9.  A possessively repeated subpattern with minimum repeat count greater than
178        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
179        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
180        the first (A) could occur when it should not.
181    
182    10. Add a cast and remove a redundant test from the code.
183    
184    11. JIT should use pcre_malloc/pcre_free for allocation.
185    
186    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
187        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
188        is anything other than /usr, -L is still shown).
189    
190    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
191    
192    14. Perl does not support \N without a following name in a [] class; PCRE now
193        also gives an error.
194    
195    15. If a forward reference was repeated with an upper limit of around 2000,
196        it caused the error "internal error: overran compiling workspace". The
197        maximum number of forward references (including repeats) was limited by the
198        internal workspace, and dependent on the LINK_SIZE. The code has been
199        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
200        the default depends on LINK_SIZE. There is a new upper limit (for safety)
201        of around 200,000 forward references. While doing this, I also speeded up
202        the filling in of repeated forward references.
203    
204    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
205        incorrectly expecting the subject to contain another "a" after the start.
206    
207    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
208        in the match, the SKIP should be ignored. This was not happening; instead
209        the SKIP was being treated as NOMATCH. For patterns such as
210        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
211        tested.
212    
213    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
214        now much more compatible with Perl, in particular in cases where the result
215        is a non-match for a non-anchored pattern. For example, if
216        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
217        "m", where previously it did not return a name. A side effect of this
218        change is that for partial matches, the last encountered mark name is
219        returned, as for non matches. A number of tests that were previously not
220        Perl-compatible have been moved into the Perl-compatible test files. The
221        refactoring has had the pleasing side effect of removing one argument from
222        the match() function, thus reducing its stack requirements.
223    
224    19. If the /S+ option was used in pcretest to study a pattern using JIT,
225        subsequent uses of /S (without +) incorrectly behaved like /S+.
226    
227    21. Retrieve executable code size support for the JIT compiler and fixing
228        some warnings.
229    
230    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
231        not work when the shorter character appeared right at the end of the
232        subject string.
233    
234    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
235        systems.
236    
237    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
238        output it when the /M option is used in pcretest.
239    
240    25. The CheckMan script was not being included in the distribution. Also, added
241        an explicit "perl" to run Perl scripts from the PrepareRelease script
242        because this is reportedly needed in Windows.
243    
244    26. If study data was being save in a file and studying had not found a set of
245        "starts with" bytes for the pattern, the data written to the file (though
246        never used) was taken from uninitialized memory and so caused valgrind to
247        complain.
248    
249    27. Updated RunTest.bat as provided by Sheri Pierce.
250    
251    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
252    
253    29. Computation of memory usage for the table of capturing group names was
254        giving an unnecessarily large value.
255    
256    
257    Version 8.20 21-Oct-2011
258    ------------------------
259    
260    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
261        a POSIX class. After further experiments with Perl, which convinced me that
262        Perl has bugs and confusions, a closing square bracket is no longer allowed
263        in a POSIX name. This bug also affected patterns with classes that started
264        with full stops.
265    
266    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
267        captured substring, but while checking the failing first alternative,
268        substring 1 is temporarily captured. If the output vector supplied to
269        pcre_exec() was not big enough for this capture, the yield of the function
270        was still zero ("insufficient space for captured substrings"). This cannot
271        be totally fixed without adding another stack variable, which seems a lot
272        of expense for a edge case. However, I have improved the situation in cases
273        such as /(a)(b)x|abc/ matched against "abc", where the return code
274        indicates that fewer than the maximum number of slots in the ovector have
275        been set.
276    
277    3.  Related to (2) above: when there are more back references in a pattern than
278        slots in the output vector, pcre_exec() uses temporary memory during
279        matching, and copies in the captures as far as possible afterwards. It was
280        using the entire output vector, but this conflicts with the specification
281        that only 2/3 is used for passing back captured substrings. Now it uses
282        only the first 2/3, for compatibility. This is, of course, another edge
283        case.
284    
285    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
286        main code base, and can be used by building with --enable-jit. When this is
287        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
288        runtime --no-jit option is given.
289    
290    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
291        ovector, the return from the function was zero, implying that there were
292        other matches that did not fit. The correct "exactly full" value is now
293        returned.
294    
295    6.  If a subpattern that was called recursively or as a subroutine contained
296        (*PRUNE) or any other control that caused it to give a non-standard return,
297        invalid errors such as "Error -26 (nested recursion at the same subject
298        position)" or even infinite loops could occur.
299    
300    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
301        computing the minimum length on reaching *ACCEPT, and so ended up with the
302        wrong value of 1 rather than 0. Further investigation indicates that
303        computing a minimum subject length in the presence of *ACCEPT is difficult
304        (think back references, subroutine calls), and so I have changed the code
305        so that no minimum is registered for a pattern that contains *ACCEPT.
306    
307    8.  If (*THEN) was present in the first (true) branch of a conditional group,
308        it was not handled as intended. [But see 16 below.]
309    
310    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
311        Sheri Pierce.
312    
313    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
314        the first byte in a match must be "a".
315    
316    11. Change 17 for 8.13 increased the recursion depth for patterns like
317        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
318        pattern contains any instances of (*THEN). If it does not, the old
319        optimizations are restored. It would be nice to do this on a per-group
320        basis, but at the moment that is not feasible.
321    
322    12. In some environments, the output of pcretest -C is CRLF terminated. This
323        broke RunTest's code that checks for the link size. A single white space
324        character after the value is now allowed for.
325    
326    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
327        For "fr", it uses the Windows-specific input and output files.
328    
329    14. If (*THEN) appeared in a group that was called recursively or as a
330        subroutine, it did not work as intended. [But see next item.]
331    
332    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
333        pattern fragments (but not containing any | characters). If A and B are
334        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
335        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
336        D. In other words, Perl considers parentheses that do not contain any |
337        characters to be part of a surrounding alternative, whereas PCRE was
338        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
339        differently. PCRE now behaves in the same way as Perl, except in the case
340        of subroutine/recursion calls such as (?1) which have in any case always
341        been different (but PCRE had them first :-).
342    
343    16. Related to 15 above: Perl does not treat the | in a conditional group as
344        creating alternatives. Such a group is treated in the same way as an
345        ordinary group without any | characters when processing (*THEN). PCRE has
346        been changed to match Perl's behaviour.
347    
348    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
349        RunGrepTest script failed.
350    
351    18. Change 22 for version 13 caused atomic groups to use more stack. This is
352        inevitable for groups that contain captures, but it can lead to a lot of
353        stack use in large patterns. The old behaviour has been restored for atomic
354        groups that do not contain any capturing parentheses.
355    
356    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
357        suppress the check for a minimum subject length at run time. (If it was
358        given to pcre_exec() or pcre_dfa_exec() it did work.)
359    
360    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
361        fail to work when decoding hex characters in data strings in EBCDIC
362        environments.
363    
364    21. It appears that in at least one Mac OS environment, the isxdigit() function
365        is implemented as a macro that evaluates to its argument more than once,
366        contravening the C 90 Standard (I haven't checked a later standard). There
367        was an instance in pcretest which caused it to go wrong when processing
368        \x{...} escapes in subject strings. The has been rewritten to avoid using
369        things like p++ in the argument of isxdigit().
370    
371    
372    Version 8.13 16-Aug-2011
373    ------------------------
374    
375    1.  The Unicode data tables have been updated to Unicode 6.0.0.
376    
377    2.  Two minor typos in pcre_internal.h have been fixed.
378    
379    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
380        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
381        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
382    
383    4.  There were a number of related bugs in the code for matching backrefences
384        caselessly in UTF-8 mode when codes for the characters concerned were
385        different numbers of bytes. For example, U+023A and U+2C65 are an upper
386        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
387        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
388        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
389        2-byte code at the end of the subject (it thought there wasn't enough data
390        left).
391    
392    5.  Comprehensive information about what went wrong is now returned by
393        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
394        as the output vector has at least 2 elements. The offset of the start of
395        the failing character and a reason code are placed in the vector.
396    
397    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
398        now returned is for the first byte of the failing character, instead of the
399        last byte inspected. This is an incompatible change, but I hope it is small
400        enough not to be a problem. It makes the returned offset consistent with
401        pcre_exec() and pcre_dfa_exec().
402    
403    7.  pcretest now gives a text phrase as well as the error number when
404        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
405        failure, the offset and reason code are output.
406    
407    8.  When \R was used with a maximizing quantifier it failed to skip backwards
408        over a \r\n pair if the subsequent match failed. Instead, it just skipped
409        back over a single character (\n). This seems wrong (because it treated the
410        two characters as a single entity when going forwards), conflicts with the
411        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
412        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
413        has been changed.
414    
415    9.  Some internal refactoring has changed the processing so that the handling
416        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
417        time (the PCRE_DOTALL option was changed this way some time ago: version
418        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
419        which was always a bit of a fudge. It also means that there is one less
420        argument for the match() function, which reduces its stack requirements
421        slightly. This change also fixes an incompatibility with Perl: the pattern
422        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
423    
424    10. More internal refactoring has drastically reduced the number of recursive
425        calls to match() for possessively repeated groups such as (abc)++ when
426        using pcre_exec().
427    
428    11. While implementing 10, a number of bugs in the handling of groups were
429        discovered and fixed:
430    
431        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
432        (a|)*(?1) gave a compile-time internal error.
433        ((a|)+)+  did not notice that the outer group could match an empty string.
434        (^a|^)+   was not marked as anchored.
435        (.*a|.*)+ was not marked as matching at start or after a newline.
436    
437    12. Yet more internal refactoring has removed another argument from the match()
438        function. Special calls to this function are now indicated by setting a
439        value in a variable in the "match data" data block.
440    
441    13. Be more explicit in pcre_study() instead of relying on "default" for
442        opcodes that mean there is no starting character; this means that when new
443        ones are added and accidentally left out of pcre_study(), testing should
444        pick them up.
445    
446    14. The -s option of pcretest has been documented for ages as being an old
447        synonym of -m (show memory usage). I have changed it to mean "force study
448        for every regex", that is, assume /S for every regex. This is similar to -i
449        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
450        using it. It makes it easier to run collections of tests with and without
451        study enabled, and thereby test pcre_study() more easily. All the standard
452        tests are now run with and without -s (but some patterns can be marked as
453        "never study" - see 20 below).
454    
455    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
456        restoration of the capturing data to the outer values was not happening
457        correctly.
458    
459    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
460        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
461        pattern had matched an empty string, and so incorrectly returned a no
462        match.
463    
464    17. There was optimizing code for the last branch of non-capturing parentheses,
465        and also for the obeyed branch of a conditional subexpression, which used
466        tail recursion to cut down on stack usage. Unfortunately, now that there is
467        the possibility of (*THEN) occurring in these branches, tail recursion is
468        no longer possible because the return has to be checked for (*THEN). These
469        two optimizations have therefore been removed. [But see 8.20/11 above.]
470    
471    18. If a pattern containing \R was studied, it was assumed that \R always
472        matched two bytes, thus causing the minimum subject length to be
473        incorrectly computed because \R can also match just one byte.
474    
475    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
476        was incorrectly computed.
477    
478    20. If /S is present twice on a test pattern in pcretest input, it now
479        *disables* studying, thereby overriding the use of -s on the command line
480        (see 14 above). This is necessary for one or two tests to keep the output
481        identical in both cases.
482    
483    21. When (*ACCEPT) was used in an assertion that matched an empty string and
484        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
485    
486    22. When an atomic group that contained a capturing parenthesis was
487        successfully matched, but the branch in which it appeared failed, the
488        capturing was not being forgotten if a higher numbered group was later
489        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
490        group 1 to "a", when in fact it should be unset. This applied to multi-
491        branched capturing and non-capturing groups, repeated or not, and also to
492        positive assertions (capturing in negative assertions does not happen
493        in PCRE) and also to nested atomic groups.
494    
495    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
496        subject after a captured substring, to make it easier to tell which of a
497        number of identical substrings has been captured.
498    
499    24. The way atomic groups are processed by pcre_exec() has been changed so that
500        if they are repeated, backtracking one repetition now resets captured
501        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
502        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
503        "aaa". Previously, it would have been "a". As part of this code
504        refactoring, the way recursive calls are handled has also been changed.
505    
506    25. If an assertion condition captured any substrings, they were not passed
507        back unless some other capturing happened later. For example, if
508        (?(?=(a))a) was matched against "a", no capturing was returned.
509    
510    26. When studying a pattern that contained subroutine calls or assertions,
511        the code for finding the minimum length of a possible match was handling
512        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
513        group 1 called group 2 while simultaneously a separate group 2 called group
514        1). A stack overflow occurred in this case. I have fixed this by limiting
515        the recursion depth to 10.
516    
517    27. Updated RunTest.bat in the distribution to the version supplied by Tom
518        Fortmann. This supports explicit test numbers on the command line, and has
519        argument validation and error reporting.
520    
521    28. An instance of \X with an unlimited repeat could fail if at any point the
522        first character it looked at was a mark character.
523    
524    29. Some minor code refactoring concerning Unicode properties and scripts
525        should reduce the stack requirement of match() slightly.
526    
527    30. Added the '=' option to pcretest to check the setting of unused capturing
528        slots at the end of the pattern, which are documented as being -1, but are
529        not included in the return count.
530    
531    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
532        compiled something random. Now it gives a compile-time error (as does
533        Perl).
534    
535    32. A *MARK encountered during the processing of a positive assertion is now
536        recorded and passed back (compatible with Perl).
537    
538    33. If --only-matching or --colour was set on a pcregrep call whose pattern
539        had alternative anchored branches, the search for a second match in a line
540        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
541        matched the line "0102" twice. The same bug affected patterns that started
542        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
543        twice.
544    
545    34. Previously, PCRE did not allow quantification of assertions. However, Perl
546        does, and because of capturing effects, quantifying parenthesized
547        assertions may at times be useful. Quantifiers are now allowed for
548        parenthesized assertions.
549    
550    35. A minor code tidy in pcre_compile() when checking options for \R usage.
551    
552    36. \g was being checked for fancy things in a character class, when it should
553        just be a literal "g".
554    
555    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
556        appearance of a nested POSIX class supersedes an apparent external class.
557        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
558        unescaped square brackets may also appear as part of class names. For
559        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
560        more like Perl. (But see 8.20/1 above.)
561    
562    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
563        was because it thought it was \N{name}, which is not supported).
564    
565    39. Add minix to OS list not supporting the -S option in pcretest.
566    
567    40. PCRE tries to detect cases of infinite recursion at compile time, but it
568        cannot analyze patterns in sufficient detail to catch mutual recursions
569        such as ((?1))((?2)). There is now a runtime test that gives an error if a
570        subgroup is called recursively as a subpattern for a second time at the
571        same position in the subject string. In previous releases this might have
572        been caught by the recursion limit, or it might have run out of stack.
573    
574    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
575        happen only once. PCRE was, however incorrectly giving a compile time error
576        "recursive call could loop indefinitely" because it cannot analyze the
577        pattern in sufficient detail. The compile time test no longer happens when
578        PCRE is compiling a conditional subpattern, but actual runaway loops are
579        now caught at runtime (see 40 above).
580    
581    42. It seems that Perl allows any characters other than a closing parenthesis
582        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
583        has been changed to be the same.
584    
585    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
586        as not to get warnings when autogen.sh is called. Also changed
587        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
588    
589    44. To help people who use pcregrep to scan files containing exceedingly long
590        lines, the following changes have been made:
591    
592        (a) The default value of the buffer size parameter has been increased from
593            8K to 20K. (The actual buffer used is three times this size.)
594    
595        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
596            PCRE is built.
597    
598        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
599            to be set at run time.
600    
601        (d) Numerical values in pcregrep options can be followed by K or M, for
602            example --buffer-size=50K.
603    
604        (e) If a line being scanned overflows pcregrep's buffer, an error is now
605            given and the return code is set to 2.
606    
607    45. Add a pointer to the latest mark to the callout data block.
608    
609    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
610        partial match of an empty string instead of no match. This was specific to
611        the use of ".".
612    
613    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
614        complete match instead of a partial match. This bug was dependent on both
615        the PCRE_UTF8 and PCRE_DOTALL options being set.
616    
617    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
618        starting byte set, because \b was not being ignored.
619    
620    
621    Version 8.12 15-Jan-2011
622    ------------------------
623    
624    1.  Fixed some typos in the markup of the man pages, and wrote a script that
625        checks for such things as part of the documentation building process.
626    
627    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
628        --match-limit and --recursion-limit options (added for 8.11). In
629        particular, this made one of the standard tests fail. (The integer value
630        went into the wrong half of a long int.)
631    
632    3.  If the --colour option was given to pcregrep with -v (invert match), it
633        did strange things, either producing crazy output, or crashing. It should,
634        of course, ignore a request for colour when reporting lines that do not
635        match.
636    
637    4.  Another pcregrep bug caused similar problems if --colour was specified with
638        -M (multiline) and the pattern match finished with a line ending.
639    
640    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
641        matched in multiline mode, the following line was shown as part of the
642        match. This seems wrong, so I have changed it.
643    
644    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
645        the check for further matches in the same line (so they could be coloured)
646        to overrun the end of the current line. If another match was found, it was
647        incorrectly shown (and then shown again when found in the next line).
648    
649    7.  If pcregrep was compiled under Windows, there was a reference to the
650        function pcregrep_exit() before it was defined. I am assuming this was
651        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
652        reported by a user. I've moved the definition above the reference.
653    
654    
655    Version 8.11 10-Dec-2010
656    ------------------------
657    
658    1.  (*THEN) was not working properly if there were untried alternatives prior
659        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
660        backtracked to try for "b" instead of moving to the next alternative branch
661        at the same level (in this case, to look for "c"). The Perl documentation
662        is clear that when (*THEN) is backtracked onto, it goes to the "next
663        alternative in the innermost enclosing group".
664    
665    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
666        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
667        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
668        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
669        (*THEN).
670    
671    3.  If \s appeared in a character class, it removed the VT character from
672        the class, even if it had been included by some previous item, for example
673        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
674        of \s, but is part of the POSIX "space" class.)
675    
676    4.  A partial match never returns an empty string (because you can always
677        match an empty string at the end of the subject); however the checking for
678        an empty string was starting at the "start of match" point. This has been
679        changed to the "earliest inspected character" point, because the returned
680        data for a partial match starts at this character. This means that, for
681        example, /(?<=abc)def/ gives a partial match for the subject "abc"
682        (previously it gave "no match").
683    
684    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
685        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
686        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
687        has an implication that the given string is incomplete (because a partial
688        match is preferred over a full match). For this reason, these items now
689        give a partial match in this situation. [Aside: previously, the one case
690        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
691        match rather than a full match, which was wrong by the old rules, but is
692        now correct.]
693    
694    6.  There was a bug in the handling of #-introduced comments, recognized when
695        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
696        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
697        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
698        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
699        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
700        places in pcre_compile().
701    
702    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
703        comments when looking ahead for named forward references to subpatterns,
704        the only newline sequence it recognized was NL. It now handles newlines
705        according to the set newline convention.
706    
707    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
708        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
709        cater for a lack of strerror(). These oversights have been fixed.
710    
711    9.  Added --match-limit and --recursion-limit to pcregrep.
712    
713    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
714    
715    11. When the -o option was used, pcregrep was setting a return code of 1, even
716        when matches were found, and --line-buffered was not being honoured.
717    
718    12. Added an optional parentheses number to the -o and --only-matching options
719        of pcregrep.
720    
721    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
722        can match an empty string. The code to do it in pcretest and pcredemo
723        needed fixing:
724    
725        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
726            only one byte after an empty string match just before CRLF (this case
727            just got forgotten; "any" and "anycrlf" were OK).
728    
729        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
730            mode when an empty string match preceded an ASCII character followed by
731            a non-ASCII character. (The code for advancing by one character rather
732            than one byte was nonsense.)
733    
734        (c) The pcredemo.c sample program did not have any code at all to handle
735            the cases when CRLF is a valid newline sequence.
736    
737    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
738        as a starting offset was within the subject string. There is now a new
739        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
740        negative or greater than the length of the string. In order to test this,
741        pcretest is extended to allow the setting of negative starting offsets.
742    
743    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
744        starting offset points to the beginning of a UTF-8 character was
745        unnecessarily clumsy. I tidied it up.
746    
747    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
748        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
749    
750    17. Nobody had reported that the --include_dir option, which was added in
751        release 7.7 should have been called --include-dir (hyphen, not underscore)
752        for compatibility with GNU grep. I have changed it to --include-dir, but
753        left --include_dir as an undocumented synonym, and the same for
754        --exclude-dir, though that is not available in GNU grep, at least as of
755        release 2.5.4.
756    
757    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
758        characters from a string of bytes) have been redefined so as not to use
759        loops, in order to improve performance in some environments. At the same
760        time, I abstracted some of the common code into auxiliary macros to save
761        repetition (this should not affect the compiled code).
762    
763    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
764        compile-time error is now given if \c is not followed by an ASCII
765        character, that is, a byte less than 128. (In EBCDIC mode, the code is
766        different, and any byte value is allowed.)
767    
768    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
769        START_OPTIMIZE option, which is now allowed at compile time - but just
770        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
771        to pcregrep and other applications that have no direct access to PCRE
772        options. The new /Y option in pcretest sets this option when calling
773        pcre_compile().
774    
775    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
776        back references. Groups containing recursive back references were forced to
777        be atomic by that change, but in the case of named groups, the amount of
778        memory required was incorrectly computed, leading to "Failed: internal
779        error: code overflow". This has been fixed.
780    
781    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
782        pcretest.c, to avoid build problems in some Borland environments.
783    
784    
785    Version 8.10 25-Jun-2010
786    ------------------------
787    
788    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
789        THEN.
790    
791    2.  (*ACCEPT) was not working when inside an atomic group.
792    
793    3.  Inside a character class, \B is treated as a literal by default, but
794        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
795        causes the error). The code is unchanged, but I tidied the documentation.
796    
797    4.  Inside a character class, PCRE always treated \R and \X as literals,
798        whereas Perl faults them if its -w option is set. I have changed PCRE so
799        that it faults them when PCRE_EXTRA is set.
800    
801    5.  Added support for \N, which always matches any character other than
802        newline. (It is the same as "." when PCRE_DOTALL is not set.)
803    
804    6.  When compiling pcregrep with newer versions of gcc which may have
805        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
806        declared with attribute warn_unused_result" were given. Just casting the
807        result to (void) does not stop the warnings; a more elaborate fudge is
808        needed. I've used a macro to implement this.
809    
810    7.  Minor change to pcretest.c to avoid a compiler warning.
811    
812    8.  Added four artifical Unicode properties to help with an option to make
813        \s etc use properties (see next item). The new properties are: Xan
814        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
815    
816    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
817        use Unicode properties. (*UCP) at the start of a pattern can be used to set
818        this option. Modified pcretest to add /W to test this facility. Added
819        REG_UCP to make it available via the POSIX interface.
820    
821    10. Added --line-buffered to pcregrep.
822    
823    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
824        studied, and the match started with a letter with a code point greater than
825        127 whose first byte was different to the first byte of the other case of
826        the letter, the other case of this starting letter was not recognized
827        (#976).
828    
829    12. If a pattern that was studied started with a repeated Unicode property
830        test, for example, \p{Nd}+, there was the theoretical possibility of
831        setting up an incorrect bitmap of starting bytes, but fortunately it could
832        not have actually happened in practice until change 8 above was made (it
833        added property types that matched character-matching opcodes).
834    
835    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
836        possible starting bytes for non-anchored patterns.
837    
838    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
839        \R, and also a number of cases that involve Unicode properties, both
840        explicit and implicit when PCRE_UCP is set.
841    
842    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
843        input, it could crash or give wrong results if characters with values
844        greater than 0xc0 were present in the subject string. (Detail: it assumed
845        UTF-8 input when processing these items.)
846    
847    16. Added a lot of (int) casts to avoid compiler warnings in systems where
848        size_t is 64-bit (#991).
849    
850    17. Added a check for running out of memory when PCRE is compiled with
851        --disable-stack-for-recursion (#990).
852    
853    18. If the last data line in a file for pcretest does not have a newline on
854        the end, a newline was missing in the output.
855    
856    19. The default pcre_chartables.c file recognizes only ASCII characters (values
857        less than 128) in its various bitmaps. However, there is a facility for
858        generating tables according to the current locale when PCRE is compiled. It
859        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
860        characters, are recognized by isspace() and therefore were getting set in
861        these tables, and indeed these tables seem to approximate to ISO 8859. This
862        caused a problem in UTF-8 mode when pcre_study() was used to create a list
863        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
864        which of course cannot start UTF-8 characters. I have changed the code so
865        that only real ASCII characters (less than 128) and the correct starting
866        bytes for UTF-8 encodings are set for characters greater than 127 when in
867        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
868        altogether.)
869    
870    20. Added the /T option to pcretest so as to be able to run tests with non-
871        standard character tables, thus making it possible to include the tests
872        used for 19 above in the standard set of tests.
873    
874    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
875        reference to a subpattern the other side of a comment that contains an
876        opening parenthesis caused either an internal compiling error, or a
877        reference to the wrong subpattern.
878    
879    
880    Version 8.02 19-Mar-2010
881    ------------------------
882    
883    1.  The Unicode data tables have been updated to Unicode 5.2.0.
884    
885    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
886        configured.
887    
888    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
889        original author of that file, following a query about its status.
890    
891    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
892        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
893    
894    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
895        quantifier applied to a forward-referencing subroutine call, could compile
896        incorrect code or give the error "internal error: previously-checked
897        referenced subpattern not found".
898    
899    6.  Both MS Visual Studio and Symbian OS have problems with initializing
900        variables to point to external functions. For these systems, therefore,
901        pcre_malloc etc. are now initialized to local functions that call the
902        relevant global functions.
903    
904    7.  There were two entries missing in the vectors called coptable and poptable
905        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
906        I've fixed the data, and added a kludgy way of testing at compile time that
907        the lengths are correct (equal to the number of opcodes).
908    
909    8.  Following on from 7, I added a similar kludge to check the length of the
910        eint vector in pcreposix.c.
911    
912    9.  Error texts for pcre_compile() are held as one long string to avoid too
913        much relocation at load time. To find a text, the string is searched,
914        counting zeros. There was no check for running off the end of the string,
915        which could happen if a new error number was added without updating the
916        string.
917    
918    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
919    
920    11. \K was not working if it appeared in an atomic group or in a group that
921        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
922        \K is "not well defined" if used in an assertion. PCRE now accepts it if
923        the assertion is positive, but not if it is negative.
924    
925    12. Change 11 fortuitously reduced the size of the stack frame used in the
926        "match()" function of pcre_exec.c by one pointer. Forthcoming
927        implementation of support for (*MARK) will need an extra pointer on the
928        stack; I have reserved it now, so that the stack frame size does not
929        decrease.
930    
931    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
932        item in branch that calls a recursion is a subroutine call - as in the
933        second branch in the above example - was incorrectly given the compile-
934        time error "recursive call could loop indefinitely" because pcre_compile()
935        was not correctly checking the subroutine for matching a non-empty string.
936    
937    14. The checks for overrunning compiling workspace could trigger after an
938        overrun had occurred. This is a "should never occur" error, but it can be
939        triggered by pathological patterns such as hundreds of nested parentheses.
940        The checks now trigger 100 bytes before the end of the workspace.
941    
942    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
943    
944    
945    Version 8.01 19-Jan-2010
946    ------------------------
947    
948    1.  If a pattern contained a conditional subpattern with only one branch (in
949        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
950        computed the wrong minimum data length (which is of course zero for such
951        subpatterns). This could cause incorrect "no match" results.
952    
953    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
954        the pattern is reset in the first branch, pcre_compile() failed with
955        "internal error: code overflow at offset...". This happened only when
956        the reset was to the original external option setting. (An optimization
957        abstracts leading options settings into an external setting, which was the
958        cause of this.)
959    
960    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
961        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
962        assertion pattern did not match (meaning that the assertion was true), it
963        was incorrectly treated as false if the SKIP had been reached during the
964        matching. This also applied to assertions used as conditions.
965    
966    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
967        assertion subpattern, including such a pattern used as a condition,
968        unpredictable results occurred, instead of the error return
969        PCRE_ERROR_DFA_UITEM.
970    
971    5.  The C++ GlobalReplace function was not working like Perl for the special
972        situation when an empty string is matched. It now does the fancy magic
973        stuff that is necessary.
974    
975    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
976        removed. (These were left over from very, very early versions of PCRE.)
977    
978    7.  Some cosmetic changes to the code to make life easier when compiling it
979        as part of something else:
980    
981        (a) Change DEBUG to PCRE_DEBUG.
982    
983        (b) In pcre_compile(), rename the member of the "branch_chain" structure
984            called "current" as "current_branch", to prevent a collision with the
985            Linux macro when compiled as a kernel module.
986    
987        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
988            prevent a collision with the Linux macro when compiled as a kernel
989            module.
990    
991    8.  In pcre_compile() there are some checks for integer overflows that used to
992        cast potentially large values to (double). This has been changed to that
993        when building, a check for int64_t is made, and if it is found, it is used
994        instead, thus avoiding the use of floating point arithmetic. (There is no
995        other use of FP in PCRE.) If int64_t is not found, the fallback is to
996        double.
997    
998    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
999        2005 (difference between two addresses compared to an unsigned value).
1000    
1001    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
1002        custom one, because of the following reported problem in Windows:
1003    
1004          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
1005              under Win32.
1006          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
1007              therefore missing the function definition.
1008          - The compiler thus generates a "C" signature for the test function.
1009          - The linker fails to find the "C" function.
1010          - PCRE fails to configure if asked to do so against libbz2.
1011    
1012    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
1013        messages were output:
1014    
1015          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
1016          rerunning libtoolize, to keep the correct libtool macros in-tree.
1017          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
1018    
1019        I have done both of these things.
1020    
1021    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
1022        most of the time, it *can* run out if it is given a pattern that contains a
1023        runaway infinite recursion. I updated the discussion in the pcrestack man
1024        page.
1025    
1026    13. Now that we have gone to the x.xx style of version numbers, the minor
1027        version may start with zero. Using 08 or 09 is a bad idea because users
1028        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
1029        interpreted as invalid octal numbers. I've updated the previous comment in
1030        configure.ac, and also added a check that gives an error if 08 or 09 are
1031        used.
1032    
1033    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
1034        causing partial matching to fail when the end of the subject matched \W
1035        in a UTF-8 pattern where \W was quantified with a minimum of 3.
1036    
1037    15. There were some discrepancies between the declarations in pcre_internal.h
1038        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
1039        their definitions. The declarations used "const uschar *" and the
1040        definitions used USPTR. Even though USPTR is normally defined as "const
1041        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
1042        reported that: "This difference in casting confuses some C++ compilers, for
1043        example, SunCC recognizes above declarations as different functions and
1044        generates broken code for hbpcre." I have changed the declarations to use
1045        USPTR.
1046    
1047    16. GNU libtool is named differently on some systems. The autogen.sh script now
1048        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
1049        (FreeBSD).
1050    
1051    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
1052        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
1053        comment: "Figure out how to create a longlong from a string: strtoll and
1054        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
1055        instance, but it only takes 2 args instead of 3!"
1056    
1057    18. A subtle bug concerned with back references has been fixed by a change of
1058        specification, with a corresponding code fix. A pattern such as
1059        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
1060        refers, was giving matches when it shouldn't. For example, xa=xaaa would
1061        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
1062        same bug. Such groups have to be quantified to be useful, or contained
1063        inside another quantified group. (If there's no repetition, the reference
1064        can never match.) The problem arises because, having left the group and
1065        moved on to the rest of the pattern, a later failure that backtracks into
1066        the group uses the captured value from the final iteration of the group
1067        rather than the correct earlier one. I have fixed this in PCRE by forcing
1068        any group that contains a reference to itself to be an atomic group; that
1069        is, there cannot be any backtracking into it once it has completed. This is
1070        similar to recursive and subroutine calls.
1071    
1072    
1073    Version 8.00 19-Oct-09
1074    ----------------------
1075    
1076    1.  The table for translating pcre_compile() error codes into POSIX error codes
1077        was out-of-date, and there was no check on the pcre_compile() error code
1078        being within the table. This could lead to an OK return being given in
1079        error.
1080    
1081    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
1082        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
1083        in a Windows environment.
1084    
1085    3.  The pcregrep --count option prints the count for each file even when it is
1086        zero, as does GNU grep. However, pcregrep was also printing all files when
1087        --files-with-matches was added. Now, when both options are given, it prints
1088        counts only for those files that have at least one match. (GNU grep just
1089        prints the file name in this circumstance, but including the count seems
1090        more useful - otherwise, why use --count?) Also ensured that the
1091        combination -clh just lists non-zero counts, with no names.
1092    
1093    4.  The long form of the pcregrep -F option was incorrectly implemented as
1094        --fixed_strings instead of --fixed-strings. This is an incompatible change,
1095        but it seems right to fix it, and I didn't think it was worth preserving
1096        the old behaviour.
1097    
1098    5.  The command line items --regex=pattern and --regexp=pattern were not
1099        recognized by pcregrep, which required --regex pattern or --regexp pattern
1100        (with a space rather than an '='). The man page documented the '=' forms,
1101        which are compatible with GNU grep; these now work.
1102    
1103    6.  No libpcreposix.pc file was created for pkg-config; there was just
1104        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
1105    
1106    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
1107        when UCP support is not needed, by modifying the Python script that
1108        generates it from Unicode data files. This should not matter if the module
1109        is correctly used as a library, but I received one complaint about 50K of
1110        unwanted data. My guess is that the person linked everything into his
1111        program rather than using a library. Anyway, it does no harm.
1112    
1113    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
1114        was a minimum greater than 1 for a wide character in a possessive
1115        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
1116        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
1117        character. Chaos in the form of incorrect output or a compiling loop could
1118        result.
1119    
1120    9.  The restrictions on what a pattern can contain when partial matching is
1121        requested for pcre_exec() have been removed. All patterns can now be
1122        partially matched by this function. In addition, if there are at least two
1123        slots in the offset vector, the offset of the earliest inspected character
1124        for the match and the offset of the end of the subject are set in them when
1125        PCRE_ERROR_PARTIAL is returned.
1126    
1127    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
1128        synonymous with PCRE_PARTIAL, for backwards compatibility, and
1129        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
1130        and may be more useful for multi-segment matching.
1131    
1132    11. Partial matching with pcre_exec() is now more intuitive. A partial match
1133        used to be given if ever the end of the subject was reached; now it is
1134        given only if matching could not proceed because another character was
1135        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
1136        string "Z", which now yields "no match" instead of "partial match". In the
1137        case of pcre_dfa_exec(), "no match" is given if every matching path for the
1138        final character ended with (*FAIL).
1139    
1140    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
1141        if the pattern had a "must contain" character that was already found in the
1142        earlier partial match, unless partial matching was again requested. For
1143        example, with the pattern /dog.(body)?/, the "must contain" character is
1144        "g". If the first part-match was for the string "dog", restarting with
1145        "sbody" failed. This bug has been fixed.
1146    
1147    13. The string returned by pcre_dfa_exec() after a partial match has been
1148        changed so that it starts at the first inspected character rather than the
1149        first character of the match. This makes a difference only if the pattern
1150        starts with a lookbehind assertion or \b or \B (\K is not supported by
1151        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1152        matching functions compatible, and I think it's the right thing to do.
1153    
1154    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1155        so that the demonstration program is easily available in environments where
1156        PCRE has not been installed from source.
1157    
1158    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1159        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1160        library.
1161    
1162    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1163        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1164        is not the first non-POSIX option to be added. Clearly some people find
1165        these options useful.
1166    
1167    17. If a caller to the POSIX matching function regexec() passes a non-zero
1168        value for nmatch with a NULL value for pmatch, the value of
1169        nmatch is forced to zero.
1170    
1171    18. RunGrepTest did not have a test for the availability of the -u option of
1172        the diff command, as RunTest does. It now checks in the same way as
1173        RunTest, and also checks for the -b option.
1174    
1175    19. If an odd number of negated classes containing just a single character
1176        interposed, within parentheses, between a forward reference to a named
1177        subpattern and the definition of the subpattern, compilation crashed with
1178        an internal error, complaining that it could not find the referenced
1179        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1180        [The bug was that it was starting one character too far in when skipping
1181        over the character class, thus treating the ] as data rather than
1182        terminating the class. This meant it could skip too much.]
1183    
1184    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1185        /g option in pcretest when the pattern contains \K, which makes it possible
1186        to have an empty string match not at the start, even when the pattern is
1187        anchored. Updated pcretest and pcredemo to use this option.
1188    
1189    21. If the maximum number of capturing subpatterns in a recursion was greater
1190        than the maximum at the outer level, the higher number was returned, but
1191        with unset values at the outer level. The correct (outer level) value is
1192        now given.
1193    
1194    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1195        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1196        make it do so. The string so far is captured, making this feature
1197        compatible with Perl.
1198    
1199    23. The tests have been re-organized, adding tests 11 and 12, to make it
1200        possible to check the Perl 5.10 features against Perl 5.10.
1201    
1202    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1203        pattern matches a fixed length string. PCRE did not allow this; now it
1204        does. Neither allows recursion.
1205    
1206    25. I finally figured out how to implement a request to provide the minimum
1207        length of subject string that was needed in order to match a given pattern.
1208        (It was back references and recursion that I had previously got hung up
1209        on.) This code has now been added to pcre_study(); it finds a lower bound
1210        to the length of subject needed. It is not necessarily the greatest lower
1211        bound, but using it to avoid searching strings that are too short does give
1212        some useful speed-ups. The value is available to calling programs via
1213        pcre_fullinfo().
1214    
1215    26. While implementing 25, I discovered to my embarrassment that pcretest had
1216        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1217        study optimizations had never been tested with that matching function.
1218        Oops. What is worse, even when it was passed study data, there was a bug in
1219        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1220        were also very few tests of studied patterns with pcre_dfa_exec().
1221    
1222    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1223        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1224        on the other side of the coin, they are no longer allowed to have different
1225        names, because these cannot be distinguished in PCRE, and this has caused
1226        confusion. (This is a difference from Perl.)
1227    
1228    28. When duplicate subpattern names are present (necessarily with different
1229        numbers, as required by 27 above), and a test is made by name in a
1230        conditional pattern, either for a subpattern having been matched, or for
1231        recursion in such a pattern, all the associated numbered subpatterns are
1232        tested, and the overall condition is true if the condition is true for any
1233        one of them. This is the way Perl works, and is also more like the way
1234        testing by number works.
1235    
1236    
1237    Version 7.9 11-Apr-09
1238    ---------------------
1239    
1240    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
1241        (pcretest), all targets were linked against these libraries. This included
1242        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
1243        libraries. This caused unwanted dependencies to be created. This problem
1244        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
1245        pcretest is linked with readline.
1246    
1247    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
1248        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
1249        moved outside it again, because FALSE and TRUE are already defined in AIX,
1250        but BOOL is not.
1251    
1252    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
1253        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
1254    
1255    4.  The pcregrep documentation said spaces were inserted as well as colons (or
1256        hyphens) following file names and line numbers when outputting matching
1257        lines. This is not true; no spaces are inserted. I have also clarified the
1258        wording for the --colour (or --color) option.
1259    
1260    5.  In pcregrep, when --colour was used with -o, the list of matching strings
1261        was not coloured; this is different to GNU grep, so I have changed it to be
1262        the same.
1263    
1264    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
1265        each matching line was coloured. Now it goes on to look for further matches
1266        of any of the test patterns, which is the same behaviour as GNU grep.
1267    
1268    7.  A pattern that could match an empty string could cause pcregrep to loop; it
1269        doesn't make sense to accept an empty string match in pcregrep, so I have
1270        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
1271        seems to be how GNU grep behaves.
1272    
1273    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
1274        start or after a newline", because the conditional assertion was not being
1275        correctly handled. The rule now is that both the assertion and what follows
1276        in the first alternative must satisfy the test.
1277    
1278    9.  If auto-callout was enabled in a pattern with a conditional group whose
1279        condition was an assertion, PCRE could crash during matching, both with
1280        pcre_exec() and pcre_dfa_exec().
1281    
1282    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
1283        used for matching.
1284    
1285    11. Unicode property support in character classes was not working for
1286        characters (bytes) greater than 127 when not in UTF-8 mode.
1287    
1288    12. Added the -M command line option to pcretest.
1289    
1290    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
1291    
1292    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
1293    
1294    16. Added comments and documentation about mis-use of no_arg in the C++
1295        wrapper.
1296    
1297    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
1298        from Martin Jerabek that uses macro names for all relevant character and
1299        string constants.
1300    
1301    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
1302        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
1303        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
1304        these, but not everybody uses configure.
1305    
1306    19. A conditional group that had only one branch was not being correctly
1307        recognized as an item that could match an empty string. This meant that an
1308        enclosing group might also not be so recognized, causing infinite looping
1309        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
1310        with the subject "ab", where knowledge that the repeated group can match
1311        nothing is needed in order to break the loop.
1312    
1313    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
1314        exec(), but without supplying a callout function, matching went wrong.
1315    
1316    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
1317        leak if the size of the offset vector was greater than 30. When the vector
1318        is smaller, the saved offsets during recursion go onto a local stack
1319        vector, but for larger vectors malloc() is used. It was failing to free
1320        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
1321        error, in fact).
1322    
1323    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
1324        heapframe that is used only when UTF-8 support is enabled. This caused no
1325        problem, but was untidy.
1326    
1327    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
1328        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
1329        included within another project.
1330    
1331    24. Steven Van Ingelgem's patches to add more options to the CMake support,
1332        slightly modified by me:
1333    
1334          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
1335              not building pcregrep.
1336    
1337          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
1338              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
1339    
1340    25. Forward references, both numeric and by name, in patterns that made use of
1341        duplicate group numbers, could behave incorrectly or give incorrect errors,
1342        because when scanning forward to find the reference group, PCRE was not
1343        taking into account the duplicate group numbers. A pattern such as
1344        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
1345    
1346    26. Changed a few more instances of "const unsigned char *" to USPTR, making
1347        the feature of a custom pointer more persuasive (as requested by a user).
1348    
1349    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
1350        pcretest.c, inside #ifndefs, because it seems they are sometimes already
1351        pre-defined.
1352    
1353    28. Added support for (*UTF8) at the start of a pattern.
1354    
1355    29. Arrange for flags added by the "release type" setting in CMake to be shown
1356        in the configuration summary.
1357    
1358    
1359    Version 7.8 05-Sep-08
1360    ---------------------
1361    
1362    1.  Replaced UCP searching code with optimized version as implemented for Ad
1363        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
1364        stage table and inline lookup instead of a function, giving speed ups of 2
1365        to 5 times on some simple patterns that I tested. Permission was given to
1366        distribute the MultiStage2.py script that generates the tables (it's not in
1367        the tarball, but is in the Subversion repository).
1368    
1369    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
1370        scripts.
1371    
1372    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
1373        a group with a zero qualifier. The result of the study could be incorrect,
1374        or the function might crash, depending on the pattern.
1375    
1376    4.  Caseless matching was not working for non-ASCII characters in back
1377        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
1378        It now works when Unicode Property Support is available.
1379    
1380    5.  In pcretest, an escape such as \x{de} in the data was always generating
1381        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
1382        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
1383        truncation.
1384    
1385    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
1386    
1387    7.  Added two (int) casts to pcregrep when printing the difference of two
1388        pointers, in case they are 64-bit values.
1389    
1390    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
1391        test 2 if it fails.
1392    
1393    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
1394        and a #define of that name to empty if it is not externally set. This is to
1395        allow users of MSVC to set it if necessary.
1396    
1397    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
1398        the convenience functions in the pcre_get.c source file.
1399    
1400    11. An option change at the start of a pattern that had top-level alternatives
1401        could cause overwriting and/or a crash. This command provoked a crash in
1402        some environments:
1403    
1404          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
1405    
1406        This potential security problem was recorded as CVE-2008-2371.
1407    
1408    12. For a pattern where the match had to start at the beginning or immediately
1409        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
1410        pcre_dfa_exec() could read past the end of the passed subject if there was
1411        no match. To help with detecting such bugs (e.g. with valgrind), I modified
1412        pcretest so that it places the subject at the end of its malloc-ed buffer.
1413    
1414    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
1415        exec() might read past the end of the data buffer in UTF-8 mode.
1416    
1417    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
1418        the data contained the byte 0x85 as part of a UTF-8 character within its
1419        first line. This applied both to normal and DFA matching.
1420    
1421    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
1422        /^[^d]*?$/8 failed to match "abc".
1423    
1424    16. Added a missing copyright notice to pcrecpp_internal.h.
1425    
1426    17. Make it more clear in the documentation that values returned from
1427        pcre_exec() in ovector are byte offsets, not character counts.
1428    
1429    18. Tidied a few places to stop certain compilers from issuing warnings.
1430    
1431    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
1432        supplied by Stefan Weber. I made a further small update for 7.8 because
1433        there is a change of source arrangements: the pcre_searchfuncs.c module is
1434        replaced by pcre_ucd.c.
1435    
1436    
1437    Version 7.7 07-May-08
1438  ---------------------  ---------------------
1439    
1440  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
1441      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
1442      done by checking for the strtoq, strtoll, and _strtoi64 functions.      done by checking for the strtoq, strtoll, and _strtoi64 functions.
1443    
1444  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
1445      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
1446      it in the RE class.      it in the RE class. (See also #8 below.)
1447    
1448  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
1449      Lopes.      Lopes.
1450    
1451  4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:  4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
1452    
1453      (1) The include/exclude patterns were being applied to the whole pathnames      (1) The include/exclude patterns were being applied to the whole pathnames
1454          of files, instead of just to the final components.          of files, instead of just to the final components.
1455    
1456      (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
1457          skipped unless they satisfied the include/exclude conditions. This is          skipped unless they satisfied the include/exclude conditions. This is
1458          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
1459          pcregrep specification - which I improved to make it absolutely clear).          pcregrep specification - which I improved to make it absolutely clear).
1460          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
1461          apply the include/exclude patterns to regular files.          apply the include/exclude patterns to regular files.
1462    
1463  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
1464      --exclude_dir in the tests to avoid scanning .svn directories.      --exclude_dir in the tests to avoid scanning .svn directories.
1465    
1466  6.  Applied Craig's patch to the QuoteMeta function so that it escapes the  6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
1467      NUL character as backslash + 0 rather than backslash + NUL, because PCRE      NUL character as backslash + 0 rather than backslash + NUL, because PCRE
1468      doesn't support NULs in patterns.      doesn't support NULs in patterns.
1469    
1470    7.  Added some missing "const"s to declarations of static tables in
1471        pcre_compile.c and pcre_dfa_exec.c.
1472    
1473    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
1474        caused by fix #2  above. (Subsequently also a second patch to fix the
1475        first patch. And a third patch - this was a messy problem.)
1476    
1477    9.  Applied Craig's patch to remove the use of push_back().
1478    
1479    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
1480        matching function regexec().
1481    
1482    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
1483        which, however, unlike Perl's \g{...}, are subroutine calls, not back
1484        references. PCRE supports relative numbers with this syntax (I don't think
1485        Oniguruma does).
1486    
1487    12. Previously, a group with a zero repeat such as (...){0} was completely
1488        omitted from the compiled regex. However, this means that if the group
1489        was called as a subroutine from elsewhere in the pattern, things went wrong
1490        (an internal error was given). Such groups are now left in the compiled
1491        pattern, with a new opcode that causes them to be skipped at execution
1492        time.
1493    
1494    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
1495        to the way PCRE behaves:
1496    
1497        (a) A lone ] character is dis-allowed (Perl treats it as data).
1498    
1499        (b) A back reference to an unmatched subpattern matches an empty string
1500            (Perl fails the current match path).
1501    
1502        (c) A data ] in a character class must be notated as \] because if the
1503            first data character in a class is ], it defines an empty class. (In
1504            Perl it is not possible to have an empty class.) The empty class []
1505            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
1506            The negative empty class [^] matches any one character, independently
1507            of the DOTALL setting.
1508    
1509    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
1510        non-existent subpattern following a character class starting with ']' and
1511        containing () gave an internal compiling error instead of "reference to
1512        non-existent subpattern". Fortunately, when the pattern did exist, the
1513        compiled code was correct. (When scanning forwards to check for the
1514        existencd of the subpattern, it was treating the data ']' as terminating
1515        the class, so got the count wrong. When actually compiling, the reference
1516        was subsequently set up correctly.)
1517    
1518    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
1519        it was being rejected as not supported by pcre_dfa_exec(), even though
1520        other assertions are supported. I have made pcre_dfa_exec() support
1521        (*FAIL).
1522    
1523    16. The implementation of 13c above involved the invention of a new opcode,
1524        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
1525        cannot be changed at match time, I realized I could make a small
1526        improvement to matching performance by compiling OP_ALLANY instead of
1527        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
1528        on the OP_ANY path.
1529    
1530    17. Compiling pcretest on Windows with readline support failed without the
1531        following two fixes: (1) Make the unistd.h include conditional on
1532        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
1533    
1534    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
1535        ncurses library to be included for pcretest when ReadLine support is
1536        requested, but also to allow for it to be overridden. This patch came from
1537        Daniel Bergström.
1538    
1539    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
1540        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
1541        any errors with the current Unicode tables. Thanks to Peter Kankowski for
1542        spotting this.
1543    
1544    
1545  Version 7.6 28-Jan-08  Version 7.6 28-Jan-08
1546  ---------------------  ---------------------

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