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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.13 30-Apr-2011  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. (*COMMIT) is now correctly confined to within a recursive subpattern call.
59    
60    14. It is now possible to link pcretest with libedit as an alternative to
61        libreadline.
62    
63    
64    Version 8.30 04-February-2012
65    -----------------------------
66    
67    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
68        name is defined in ctype.h.
69    
70    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
71        only in quite long subpatterns.
72    
73    3.  Removed the function pcre_info(), which has been obsolete and deprecated
74        since it was replaced by pcre_fullinfo() in February 2000.
75    
76    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
77        match a (*MARK), and the match failed at the start of the subject, a
78        reference to memory before the start of the subject could occur. This bug
79        was introduced by fix 17 of release 8.21.
80    
81    5.  A reference to an unset group with zero minimum repetition was giving
82        totally wrong answers (in non-JavaScript-compatibility mode). For example,
83        /(another)?(\1?)test/ matched against "hello world test". This bug was
84        introduced in release 8.13.
85    
86    6.  Add support for 16-bit character strings (a large amount of work involving
87        many changes and refactorings).
88    
89    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
90        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
91        from a file.
92    
93    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
94        rounding is not applied in this particular case).
95    
96    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
97        if they appear, or are escaped, in patterns.
98    
99    10. Get rid of a number of -Wunused-but-set-variable warnings.
100    
101    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
102        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
103        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
104        also returns the mark "x". This bug applied to capturing parentheses,
105        non-capturing parentheses, and atomic parentheses. It also applied to some
106        assertions.
107    
108    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
109        information out of configure.ac instead of relying on pcre.h.generic, which
110        is not stored in the repository.
111    
112    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
113        -lreadline.
114    
115    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
116    
117    15. Applied Graycode's patch to put the top-level frame on the stack rather
118        than the heap when not using the stack for recursion. This gives a
119        performance improvement in many cases when recursion is not deep.
120    
121    16. Experimental code added to "pcretest -C" to output the stack frame size.
122    
123    
124    Version 8.21 12-Dec-2011
125    ------------------------
126    
127    1.  Updating the JIT compiler.
128    
129    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
130        are added as well.
131    
132    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
133        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
134        calling _pcre_jit_exec. Some extra comments are added.
135    
136    4.  (*MARK) settings inside atomic groups that do not contain any capturing
137        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
138        was introduced by change 18 for 8.20.
139    
140    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
141        ECMA-262 standard.
142    
143    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
144        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
145        This bug was probably introduced by change 9 of 8.13.
146    
147    7.  While fixing 6 above, I noticed that a number of other items were being
148        incorrectly rejected as "not fixed length". This arose partly because newer
149        opcodes had not been added to the fixed-length checking code. I have (a)
150        corrected the bug and added tests for these items, and (b) arranged for an
151        error to occur if an unknown opcode is encountered while checking for fixed
152        length instead of just assuming "not fixed length". The items that were
153        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
154        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
155        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
156    
157    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
158        being incorrectly compiled and would have given unpredicatble results.
159    
160    9.  A possessively repeated subpattern with minimum repeat count greater than
161        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
162        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
163        the first (A) could occur when it should not.
164    
165    10. Add a cast and remove a redundant test from the code.
166    
167    11. JIT should use pcre_malloc/pcre_free for allocation.
168    
169    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
170        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
171        is anything other than /usr, -L is still shown).
172    
173    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
174    
175    14. Perl does not support \N without a following name in a [] class; PCRE now
176        also gives an error.
177    
178    15. If a forward reference was repeated with an upper limit of around 2000,
179        it caused the error "internal error: overran compiling workspace". The
180        maximum number of forward references (including repeats) was limited by the
181        internal workspace, and dependent on the LINK_SIZE. The code has been
182        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
183        the default depends on LINK_SIZE. There is a new upper limit (for safety)
184        of around 200,000 forward references. While doing this, I also speeded up
185        the filling in of repeated forward references.
186    
187    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
188        incorrectly expecting the subject to contain another "a" after the start.
189    
190    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
191        in the match, the SKIP should be ignored. This was not happening; instead
192        the SKIP was being treated as NOMATCH. For patterns such as
193        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
194        tested.
195    
196    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
197        now much more compatible with Perl, in particular in cases where the result
198        is a non-match for a non-anchored pattern. For example, if
199        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
200        "m", where previously it did not return a name. A side effect of this
201        change is that for partial matches, the last encountered mark name is
202        returned, as for non matches. A number of tests that were previously not
203        Perl-compatible have been moved into the Perl-compatible test files. The
204        refactoring has had the pleasing side effect of removing one argument from
205        the match() function, thus reducing its stack requirements.
206    
207    19. If the /S+ option was used in pcretest to study a pattern using JIT,
208        subsequent uses of /S (without +) incorrectly behaved like /S+.
209    
210    21. Retrieve executable code size support for the JIT compiler and fixing
211        some warnings.
212    
213    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
214        not work when the shorter character appeared right at the end of the
215        subject string.
216    
217    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
218        systems.
219    
220    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
221        output it when the /M option is used in pcretest.
222    
223    25. The CheckMan script was not being included in the distribution. Also, added
224        an explicit "perl" to run Perl scripts from the PrepareRelease script
225        because this is reportedly needed in Windows.
226    
227    26. If study data was being save in a file and studying had not found a set of
228        "starts with" bytes for the pattern, the data written to the file (though
229        never used) was taken from uninitialized memory and so caused valgrind to
230        complain.
231    
232    27. Updated RunTest.bat as provided by Sheri Pierce.
233    
234    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
235    
236    29. Computation of memory usage for the table of capturing group names was
237        giving an unnecessarily large value.
238    
239    
240    Version 8.20 21-Oct-2011
241    ------------------------
242    
243    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
244        a POSIX class. After further experiments with Perl, which convinced me that
245        Perl has bugs and confusions, a closing square bracket is no longer allowed
246        in a POSIX name. This bug also affected patterns with classes that started
247        with full stops.
248    
249    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
250        captured substring, but while checking the failing first alternative,
251        substring 1 is temporarily captured. If the output vector supplied to
252        pcre_exec() was not big enough for this capture, the yield of the function
253        was still zero ("insufficient space for captured substrings"). This cannot
254        be totally fixed without adding another stack variable, which seems a lot
255        of expense for a edge case. However, I have improved the situation in cases
256        such as /(a)(b)x|abc/ matched against "abc", where the return code
257        indicates that fewer than the maximum number of slots in the ovector have
258        been set.
259    
260    3.  Related to (2) above: when there are more back references in a pattern than
261        slots in the output vector, pcre_exec() uses temporary memory during
262        matching, and copies in the captures as far as possible afterwards. It was
263        using the entire output vector, but this conflicts with the specification
264        that only 2/3 is used for passing back captured substrings. Now it uses
265        only the first 2/3, for compatibility. This is, of course, another edge
266        case.
267    
268    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
269        main code base, and can be used by building with --enable-jit. When this is
270        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
271        runtime --no-jit option is given.
272    
273    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
274        ovector, the return from the function was zero, implying that there were
275        other matches that did not fit. The correct "exactly full" value is now
276        returned.
277    
278    6.  If a subpattern that was called recursively or as a subroutine contained
279        (*PRUNE) or any other control that caused it to give a non-standard return,
280        invalid errors such as "Error -26 (nested recursion at the same subject
281        position)" or even infinite loops could occur.
282    
283    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
284        computing the minimum length on reaching *ACCEPT, and so ended up with the
285        wrong value of 1 rather than 0. Further investigation indicates that
286        computing a minimum subject length in the presence of *ACCEPT is difficult
287        (think back references, subroutine calls), and so I have changed the code
288        so that no minimum is registered for a pattern that contains *ACCEPT.
289    
290    8.  If (*THEN) was present in the first (true) branch of a conditional group,
291        it was not handled as intended. [But see 16 below.]
292    
293    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
294        Sheri Pierce.
295    
296    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
297        the first byte in a match must be "a".
298    
299    11. Change 17 for 8.13 increased the recursion depth for patterns like
300        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
301        pattern contains any instances of (*THEN). If it does not, the old
302        optimizations are restored. It would be nice to do this on a per-group
303        basis, but at the moment that is not feasible.
304    
305    12. In some environments, the output of pcretest -C is CRLF terminated. This
306        broke RunTest's code that checks for the link size. A single white space
307        character after the value is now allowed for.
308    
309    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
310        For "fr", it uses the Windows-specific input and output files.
311    
312    14. If (*THEN) appeared in a group that was called recursively or as a
313        subroutine, it did not work as intended. [But see next item.]
314    
315    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
316        pattern fragments (but not containing any | characters). If A and B are
317        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
318        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
319        D. In other words, Perl considers parentheses that do not contain any |
320        characters to be part of a surrounding alternative, whereas PCRE was
321        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
322        differently. PCRE now behaves in the same way as Perl, except in the case
323        of subroutine/recursion calls such as (?1) which have in any case always
324        been different (but PCRE had them first :-).
325    
326    16. Related to 15 above: Perl does not treat the | in a conditional group as
327        creating alternatives. Such a group is treated in the same way as an
328        ordinary group without any | characters when processing (*THEN). PCRE has
329        been changed to match Perl's behaviour.
330    
331    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
332        RunGrepTest script failed.
333    
334    18. Change 22 for version 13 caused atomic groups to use more stack. This is
335        inevitable for groups that contain captures, but it can lead to a lot of
336        stack use in large patterns. The old behaviour has been restored for atomic
337        groups that do not contain any capturing parentheses.
338    
339    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
340        suppress the check for a minimum subject length at run time. (If it was
341        given to pcre_exec() or pcre_dfa_exec() it did work.)
342    
343    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
344        fail to work when decoding hex characters in data strings in EBCDIC
345        environments.
346    
347    21. It appears that in at least one Mac OS environment, the isxdigit() function
348        is implemented as a macro that evaluates to its argument more than once,
349        contravening the C 90 Standard (I haven't checked a later standard). There
350        was an instance in pcretest which caused it to go wrong when processing
351        \x{...} escapes in subject strings. The has been rewritten to avoid using
352        things like p++ in the argument of isxdigit().
353    
354    
355    Version 8.13 16-Aug-2011
356  ------------------------  ------------------------
357    
358  1.  The Unicode data tables have been updated to Unicode 6.0.0.  1.  The Unicode data tables have been updated to Unicode 6.0.0.
# Line 20  Version 8.13 30-Apr-2011 Line 371  Version 8.13 30-Apr-2011
371      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
372      2-byte code at the end of the subject (it thought there wasn't enough data      2-byte code at the end of the subject (it thought there wasn't enough data
373      left).      left).
374    
375  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
376      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
377      as the output vector has at least 2 elements. The offset of the start of      as the output vector has at least 2 elements. The offset of the start of
378      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
379    
380  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
381      now returned is for the first byte of the failing character, instead of the      now returned is for the first byte of the failing character, instead of the
382      last byte inspected. This is an incompatible change, but I hope it is small      last byte inspected. This is an incompatible change, but I hope it is small
383      enough not to be a problem. It makes the returned offset consistent with      enough not to be a problem. It makes the returned offset consistent with
384      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
385    
386  7.  pcretest now gives a text phrase as well as the error number when  7.  pcretest now gives a text phrase as well as the error number when
387      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
388      failure, the offset and reason code are output.      failure, the offset and reason code are output.
389    
390  8.  When \R was used with a maximizing quantifier it failed to skip backwards  8.  When \R was used with a maximizing quantifier it failed to skip backwards
391      over a \r\n pair if the subsequent match failed. Instead, it just skipped      over a \r\n pair if the subsequent match failed. Instead, it just skipped
392      back over a single character (\n). This seems wrong (because it treated the      back over a single character (\n). This seems wrong (because it treated the
393      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
394      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
395      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
396      has been changed.      has been changed.
397    
398  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
399      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
400      time (the PCRE_DOTALL option was changed this way some time ago: version      time (the PCRE_DOTALL option was changed this way some time ago: version
401      7.7 change 16). This has made it possible to abolish the OP_OPT op code,      7.7 change 16). This has made it possible to abolish the OP_OPT op code,
402      which was always a bit of a fudge. It also means that there is one less      which was always a bit of a fudge. It also means that there is one less
403      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
404      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
405      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
406    
407  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
408      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
409      using pcre_exec().      using pcre_exec().
410    
411  11. While implementing 10, a number of bugs in the handling of groups were  11. While implementing 10, a number of bugs in the handling of groups were
412      discovered and fixed:      discovered and fixed:
413    
414      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
415      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
416      ((a|)+)+  did not notice that the outer group could match an empty string.      ((a|)+)+  did not notice that the outer group could match an empty string.
417      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
418      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
419    
420  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
421      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
422      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
423    
424  13. Be more explicit in pcre_study() instead of relying on "default" for  13. Be more explicit in pcre_study() instead of relying on "default" for
425      opcodes that mean there is no starting character; this means that when new      opcodes that mean there is no starting character; this means that when new
426      ones are added and accidentally left out of pcre_study(), testing should      ones are added and accidentally left out of pcre_study(), testing should
427      pick them up.      pick them up.
428    
429  14. The -s option of pcretest has been documented for ages as being an old  14. The -s option of pcretest has been documented for ages as being an old
430      synonym of -m (show memory usage). I have changed it to mean "force study      synonym of -m (show memory usage). I have changed it to mean "force study
431      for every regex", that is, assume /S for every regex. This is similar to -i      for every regex", that is, assume /S for every regex. This is similar to -i
432      and -d etc. It's slightly incompatible, but I'm hoping nobody is still      and -d etc. It's slightly incompatible, but I'm hoping nobody is still
433      using it. It makes it easier to run collection of tests with study enabled,      using it. It makes it easier to run collections of tests with and without
434      and thereby test pcre_study() more easily.      study enabled, and thereby test pcre_study() more easily. All the standard
435        tests are now run with and without -s (but some patterns can be marked as
436        "never study" - see 20 below).
437    
438  15. When (*ACCEPT) was used in a subpattern that was called recursively, the  15. When (*ACCEPT) was used in a subpattern that was called recursively, the
439      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
440      correctly.      correctly.
441    
442  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  16. If a recursively called subpattern ended with (*ACCEPT) and matched an
443      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
444      pattern had matched an empty string, and so incorrectly returned a no      pattern had matched an empty string, and so incorrectly returned a no
445      match.      match.
446    
447    17. There was optimizing code for the last branch of non-capturing parentheses,
448        and also for the obeyed branch of a conditional subexpression, which used
449        tail recursion to cut down on stack usage. Unfortunately, now that there is
450        the possibility of (*THEN) occurring in these branches, tail recursion is
451        no longer possible because the return has to be checked for (*THEN). These
452        two optimizations have therefore been removed. [But see 8.20/11 above.]
453    
454    18. If a pattern containing \R was studied, it was assumed that \R always
455        matched two bytes, thus causing the minimum subject length to be
456        incorrectly computed because \R can also match just one byte.
457    
458    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
459        was incorrectly computed.
460    
461    20. If /S is present twice on a test pattern in pcretest input, it now
462        *disables* studying, thereby overriding the use of -s on the command line
463        (see 14 above). This is necessary for one or two tests to keep the output
464        identical in both cases.
465    
466    21. When (*ACCEPT) was used in an assertion that matched an empty string and
467        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
468    
469    22. When an atomic group that contained a capturing parenthesis was
470        successfully matched, but the branch in which it appeared failed, the
471        capturing was not being forgotten if a higher numbered group was later
472        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
473        group 1 to "a", when in fact it should be unset. This applied to multi-
474        branched capturing and non-capturing groups, repeated or not, and also to
475        positive assertions (capturing in negative assertions does not happen
476        in PCRE) and also to nested atomic groups.
477    
478    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
479        subject after a captured substring, to make it easier to tell which of a
480        number of identical substrings has been captured.
481    
482    24. The way atomic groups are processed by pcre_exec() has been changed so that
483        if they are repeated, backtracking one repetition now resets captured
484        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
485        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
486        "aaa". Previously, it would have been "a". As part of this code
487        refactoring, the way recursive calls are handled has also been changed.
488    
489    25. If an assertion condition captured any substrings, they were not passed
490        back unless some other capturing happened later. For example, if
491        (?(?=(a))a) was matched against "a", no capturing was returned.
492    
493    26. When studying a pattern that contained subroutine calls or assertions,
494        the code for finding the minimum length of a possible match was handling
495        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
496        group 1 called group 2 while simultaneously a separate group 2 called group
497        1). A stack overflow occurred in this case. I have fixed this by limiting
498        the recursion depth to 10.
499    
500    27. Updated RunTest.bat in the distribution to the version supplied by Tom
501        Fortmann. This supports explicit test numbers on the command line, and has
502        argument validation and error reporting.
503    
504    28. An instance of \X with an unlimited repeat could fail if at any point the
505        first character it looked at was a mark character.
506    
507    29. Some minor code refactoring concerning Unicode properties and scripts
508        should reduce the stack requirement of match() slightly.
509    
510    30. Added the '=' option to pcretest to check the setting of unused capturing
511        slots at the end of the pattern, which are documented as being -1, but are
512        not included in the return count.
513    
514    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
515        compiled something random. Now it gives a compile-time error (as does
516        Perl).
517    
518    32. A *MARK encountered during the processing of a positive assertion is now
519        recorded and passed back (compatible with Perl).
520    
521    33. If --only-matching or --colour was set on a pcregrep call whose pattern
522        had alternative anchored branches, the search for a second match in a line
523        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
524        matched the line "0102" twice. The same bug affected patterns that started
525        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
526        twice.
527    
528    34. Previously, PCRE did not allow quantification of assertions. However, Perl
529        does, and because of capturing effects, quantifying parenthesized
530        assertions may at times be useful. Quantifiers are now allowed for
531        parenthesized assertions.
532    
533    35. A minor code tidy in pcre_compile() when checking options for \R usage.
534    
535    36. \g was being checked for fancy things in a character class, when it should
536        just be a literal "g".
537    
538    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
539        appearance of a nested POSIX class supersedes an apparent external class.
540        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
541        unescaped square brackets may also appear as part of class names. For
542        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
543        more like Perl. (But see 8.20/1 above.)
544    
545    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
546        was because it thought it was \N{name}, which is not supported).
547    
548    39. Add minix to OS list not supporting the -S option in pcretest.
549    
550    40. PCRE tries to detect cases of infinite recursion at compile time, but it
551        cannot analyze patterns in sufficient detail to catch mutual recursions
552        such as ((?1))((?2)). There is now a runtime test that gives an error if a
553        subgroup is called recursively as a subpattern for a second time at the
554        same position in the subject string. In previous releases this might have
555        been caught by the recursion limit, or it might have run out of stack.
556    
557    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
558        happen only once. PCRE was, however incorrectly giving a compile time error
559        "recursive call could loop indefinitely" because it cannot analyze the
560        pattern in sufficient detail. The compile time test no longer happens when
561        PCRE is compiling a conditional subpattern, but actual runaway loops are
562        now caught at runtime (see 40 above).
563    
564    42. It seems that Perl allows any characters other than a closing parenthesis
565        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
566        has been changed to be the same.
567    
568    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
569        as not to get warnings when autogen.sh is called. Also changed
570        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
571    
572    44. To help people who use pcregrep to scan files containing exceedingly long
573        lines, the following changes have been made:
574    
575        (a) The default value of the buffer size parameter has been increased from
576            8K to 20K. (The actual buffer used is three times this size.)
577    
578        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
579            PCRE is built.
580    
581        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
582            to be set at run time.
583    
584        (d) Numerical values in pcregrep options can be followed by K or M, for
585            example --buffer-size=50K.
586    
587        (e) If a line being scanned overflows pcregrep's buffer, an error is now
588            given and the return code is set to 2.
589    
590    45. Add a pointer to the latest mark to the callout data block.
591    
592    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
593        partial match of an empty string instead of no match. This was specific to
594        the use of ".".
595    
596    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
597        complete match instead of a partial match. This bug was dependent on both
598        the PCRE_UTF8 and PCRE_DOTALL options being set.
599    
600    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
601        starting byte set, because \b was not being ignored.
602    
603    
604  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
605  ------------------------  ------------------------

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