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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.20 12-Sep-2011
5    ------------------------
6    
7    1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
8       a POSIX class. After further experiments with Perl, which convinced me that
9       Perl has bugs and confusions, a closing square bracket is no longer allowed
10       in a POSIX name. This bug also affected patterns with classes that started
11       with full stops.
12    
13    2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured
14       substring, but while checking the failing first alternative, substring 1 is
15       temporarily captured. If the output vector supplied to pcre_exec() was not
16       big enough for this capture, the yield of the function was still zero
17       ("insufficient space for captured substrings"). This cannot be totally fixed
18       without adding another stack variable, which seems a lot of expense for a
19       edge case. However, I have improved the situation in cases such as
20       /(a)(b)x|abc/ matched against "abc", where the return code indicates that
21       fewer than the maximum number of slots in the ovector have been set.
22    
23    3. Related to (2) above: when there are more back references in a pattern than
24       slots in the output vector, pcre_exec() uses temporary memory during
25       matching, and copies in the captures as far as possible afterwards. It was
26       using the entire output vector, but this conflicts with the specification
27       that only 2/3 is used for passing back captured substrings. Now it uses only
28       the first 2/3, for compatibility. This is, of course, another edge case.
29    
30    4. Zoltan Herczeg's just-in-time compiler support has been integrated into the
31       main code base, and can be used by building with --enable-jit. When this is
32       done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
33       runtime --no-jit option is given.
34    
35    5. When the number of matches in a pcre_dfa_exec() run exactly filled the
36       ovector, the return from the function was zero, implying that there were
37       other matches that did not fit. The correct "exactly full" value is now
38       returned.
39    
40    6. If a subpattern that was called recursively or as a subroutine contained
41       (*PRUNE) or any other control that caused it to give a non-standard return,
42       invalid errors such as "Error -26 (nested recursion at the same subject
43       position)" or even infinite loops could occur.
44    
45    7. If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
46       computing the minimum length on reaching *ACCEPT, and so ended up with the
47       wrong value of 1 rather than 0. Further investigation indicates that
48       computing a minimum subject length in the presence of *ACCEPT is difficult
49       (think back references, subroutine calls), and so I have changed the code so
50       that no minimum is registered for a pattern that contains *ACCEPT.
51    
52    8. If (*THEN) was present in the first (true) branch of a conditional group,
53       it was not handled as intended.
54    
55    9. Replaced RunTest.bat with the much improved version provided by Sheri
56       Pierce.
57    
58    
59    Version 8.13 16-Aug-2011
60    ------------------------
61    
62    1.  The Unicode data tables have been updated to Unicode 6.0.0.
63    
64    2.  Two minor typos in pcre_internal.h have been fixed.
65    
66    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
67        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
68        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
69    
70    4.  There were a number of related bugs in the code for matching backrefences
71        caselessly in UTF-8 mode when codes for the characters concerned were
72        different numbers of bytes. For example, U+023A and U+2C65 are an upper
73        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
74        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
75        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
76        2-byte code at the end of the subject (it thought there wasn't enough data
77        left).
78    
79    5.  Comprehensive information about what went wrong is now returned by
80        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
81        as the output vector has at least 2 elements. The offset of the start of
82        the failing character and a reason code are placed in the vector.
83    
84    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
85        now returned is for the first byte of the failing character, instead of the
86        last byte inspected. This is an incompatible change, but I hope it is small
87        enough not to be a problem. It makes the returned offset consistent with
88        pcre_exec() and pcre_dfa_exec().
89    
90    7.  pcretest now gives a text phrase as well as the error number when
91        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
92        failure, the offset and reason code are output.
93    
94    8.  When \R was used with a maximizing quantifier it failed to skip backwards
95        over a \r\n pair if the subsequent match failed. Instead, it just skipped
96        back over a single character (\n). This seems wrong (because it treated the
97        two characters as a single entity when going forwards), conflicts with the
98        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
99        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
100        has been changed.
101    
102    9.  Some internal refactoring has changed the processing so that the handling
103        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
104        time (the PCRE_DOTALL option was changed this way some time ago: version
105        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
106        which was always a bit of a fudge. It also means that there is one less
107        argument for the match() function, which reduces its stack requirements
108        slightly. This change also fixes an incompatibility with Perl: the pattern
109        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
110    
111    10. More internal refactoring has drastically reduced the number of recursive
112        calls to match() for possessively repeated groups such as (abc)++ when
113        using pcre_exec().
114    
115    11. While implementing 10, a number of bugs in the handling of groups were
116        discovered and fixed:
117    
118        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
119        (a|)*(?1) gave a compile-time internal error.
120        ((a|)+)+  did not notice that the outer group could match an empty string.
121        (^a|^)+   was not marked as anchored.
122        (.*a|.*)+ was not marked as matching at start or after a newline.
123    
124    12. Yet more internal refactoring has removed another argument from the match()
125        function. Special calls to this function are now indicated by setting a
126        value in a variable in the "match data" data block.
127    
128    13. Be more explicit in pcre_study() instead of relying on "default" for
129        opcodes that mean there is no starting character; this means that when new
130        ones are added and accidentally left out of pcre_study(), testing should
131        pick them up.
132    
133    14. The -s option of pcretest has been documented for ages as being an old
134        synonym of -m (show memory usage). I have changed it to mean "force study
135        for every regex", that is, assume /S for every regex. This is similar to -i
136        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
137        using it. It makes it easier to run collections of tests with and without
138        study enabled, and thereby test pcre_study() more easily. All the standard
139        tests are now run with and without -s (but some patterns can be marked as
140        "never study" - see 20 below).
141    
142    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
143        restoration of the capturing data to the outer values was not happening
144        correctly.
145    
146    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
147        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
148        pattern had matched an empty string, and so incorrectly returned a no
149        match.
150    
151    17. There was optimizing code for the last branch of non-capturing parentheses,
152        and also for the obeyed branch of a conditional subexpression, which used
153        tail recursion to cut down on stack usage. Unfortunately, now that there is
154        the possibility of (*THEN) occurring in these branches, tail recursion is
155        no longer possible because the return has to be checked for (*THEN). These
156        two optimizations have therefore been removed.
157    
158    18. If a pattern containing \R was studied, it was assumed that \R always
159        matched two bytes, thus causing the minimum subject length to be
160        incorrectly computed because \R can also match just one byte.
161    
162    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
163        was incorrectly computed.
164    
165    20. If /S is present twice on a test pattern in pcretest input, it now
166        *disables* studying, thereby overriding the use of -s on the command line
167        (see 14 above). This is necessary for one or two tests to keep the output
168        identical in both cases.
169    
170    21. When (*ACCEPT) was used in an assertion that matched an empty string and
171        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
172    
173    22. When an atomic group that contained a capturing parenthesis was
174        successfully matched, but the branch in which it appeared failed, the
175        capturing was not being forgotten if a higher numbered group was later
176        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
177        group 1 to "a", when in fact it should be unset. This applied to multi-
178        branched capturing and non-capturing groups, repeated or not, and also to
179        positive assertions (capturing in negative assertions does not happen
180        in PCRE) and also to nested atomic groups.
181    
182    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
183        subject after a captured substring, to make it easier to tell which of a
184        number of identical substrings has been captured.
185    
186    24. The way atomic groups are processed by pcre_exec() has been changed so that
187        if they are repeated, backtracking one repetition now resets captured
188        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
189        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
190        "aaa". Previously, it would have been "a". As part of this code
191        refactoring, the way recursive calls are handled has also been changed.
192    
193    25. If an assertion condition captured any substrings, they were not passed
194        back unless some other capturing happened later. For example, if
195        (?(?=(a))a) was matched against "a", no capturing was returned.
196    
197    26. When studying a pattern that contained subroutine calls or assertions,
198        the code for finding the minimum length of a possible match was handling
199        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
200        group 1 called group 2 while simultaneously a separate group 2 called group
201        1). A stack overflow occurred in this case. I have fixed this by limiting
202        the recursion depth to 10.
203    
204    27. Updated RunTest.bat in the distribution to the version supplied by Tom
205        Fortmann. This supports explicit test numbers on the command line, and has
206        argument validation and error reporting.
207    
208    28. An instance of \X with an unlimited repeat could fail if at any point the
209        first character it looked at was a mark character.
210    
211    29. Some minor code refactoring concerning Unicode properties and scripts
212        should reduce the stack requirement of match() slightly.
213    
214    30. Added the '=' option to pcretest to check the setting of unused capturing
215        slots at the end of the pattern, which are documented as being -1, but are
216        not included in the return count.
217    
218    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
219        compiled something random. Now it gives a compile-time error (as does
220        Perl).
221    
222    32. A *MARK encountered during the processing of a positive assertion is now
223        recorded and passed back (compatible with Perl).
224    
225    33. If --only-matching or --colour was set on a pcregrep call whose pattern
226        had alternative anchored branches, the search for a second match in a line
227        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
228        matched the line "0102" twice. The same bug affected patterns that started
229        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
230        twice.
231    
232    34. Previously, PCRE did not allow quantification of assertions. However, Perl
233        does, and because of capturing effects, quantifying parenthesized
234        assertions may at times be useful. Quantifiers are now allowed for
235        parenthesized assertions.
236    
237    35. A minor code tidy in pcre_compile() when checking options for \R usage.
238    
239    36. \g was being checked for fancy things in a character class, when it should
240        just be a literal "g".
241    
242    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
243        appearance of a nested POSIX class supersedes an apparent external class.
244        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
245        unescaped square brackets may also appear as part of class names. For
246        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
247        more like Perl. (But see 8.20/1 above.)
248    
249    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
250        was because it thought it was \N{name}, which is not supported).
251    
252    39. Add minix to OS list not supporting the -S option in pcretest.
253    
254    40. PCRE tries to detect cases of infinite recursion at compile time, but it
255        cannot analyze patterns in sufficient detail to catch mutual recursions
256        such as ((?1))((?2)). There is now a runtime test that gives an error if a
257        subgroup is called recursively as a subpattern for a second time at the
258        same position in the subject string. In previous releases this might have
259        been caught by the recursion limit, or it might have run out of stack.
260    
261    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
262        happen only once. PCRE was, however incorrectly giving a compile time error
263        "recursive call could loop indefinitely" because it cannot analyze the
264        pattern in sufficient detail. The compile time test no longer happens when
265        PCRE is compiling a conditional subpattern, but actual runaway loops are
266        now caught at runtime (see 40 above).
267    
268    42. It seems that Perl allows any characters other than a closing parenthesis
269        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
270        has been changed to be the same.
271    
272    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
273        as not to get warnings when autogen.sh is called. Also changed
274        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
275    
276    44. To help people who use pcregrep to scan files containing exceedingly long
277        lines, the following changes have been made:
278    
279        (a) The default value of the buffer size parameter has been increased from
280            8K to 20K. (The actual buffer used is three times this size.)
281    
282        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
283            PCRE is built.
284    
285        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
286            to be set at run time.
287    
288        (d) Numerical values in pcregrep options can be followed by K or M, for
289            example --buffer-size=50K.
290    
291        (e) If a line being scanned overflows pcregrep's buffer, an error is now
292            given and the return code is set to 2.
293    
294    45. Add a pointer to the latest mark to the callout data block.
295    
296    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
297        partial match of an empty string instead of no match. This was specific to
298        the use of ".".
299    
300    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
301        complete match instead of a partial match. This bug was dependent on both
302        the PCRE_UTF8 and PCRE_DOTALL options being set.
303    
304    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
305        starting byte set, because \b was not being ignored.
306    
307    
308    Version 8.12 15-Jan-2011
309    ------------------------
310    
311    1.  Fixed some typos in the markup of the man pages, and wrote a script that
312        checks for such things as part of the documentation building process.
313    
314    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
315        --match-limit and --recursion-limit options (added for 8.11). In
316        particular, this made one of the standard tests fail. (The integer value
317        went into the wrong half of a long int.)
318    
319    3.  If the --colour option was given to pcregrep with -v (invert match), it
320        did strange things, either producing crazy output, or crashing. It should,
321        of course, ignore a request for colour when reporting lines that do not
322        match.
323    
324    4.  Another pcregrep bug caused similar problems if --colour was specified with
325        -M (multiline) and the pattern match finished with a line ending.
326    
327    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
328        matched in multiline mode, the following line was shown as part of the
329        match. This seems wrong, so I have changed it.
330    
331    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
332        the check for further matches in the same line (so they could be coloured)
333        to overrun the end of the current line. If another match was found, it was
334        incorrectly shown (and then shown again when found in the next line).
335    
336    7.  If pcregrep was compiled under Windows, there was a reference to the
337        function pcregrep_exit() before it was defined. I am assuming this was
338        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
339        reported by a user. I've moved the definition above the reference.
340    
341    
342    Version 8.11 10-Dec-2010
343    ------------------------
344    
345    1.  (*THEN) was not working properly if there were untried alternatives prior
346        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
347        backtracked to try for "b" instead of moving to the next alternative branch
348        at the same level (in this case, to look for "c"). The Perl documentation
349        is clear that when (*THEN) is backtracked onto, it goes to the "next
350        alternative in the innermost enclosing group".
351    
352    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
353        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
354        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
355        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
356        (*THEN).
357    
358    3.  If \s appeared in a character class, it removed the VT character from
359        the class, even if it had been included by some previous item, for example
360        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
361        of \s, but is part of the POSIX "space" class.)
362    
363    4.  A partial match never returns an empty string (because you can always
364        match an empty string at the end of the subject); however the checking for
365        an empty string was starting at the "start of match" point. This has been
366        changed to the "earliest inspected character" point, because the returned
367        data for a partial match starts at this character. This means that, for
368        example, /(?<=abc)def/ gives a partial match for the subject "abc"
369        (previously it gave "no match").
370    
371    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
372        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
373        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
374        has an implication that the given string is incomplete (because a partial
375        match is preferred over a full match). For this reason, these items now
376        give a partial match in this situation. [Aside: previously, the one case
377        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
378        match rather than a full match, which was wrong by the old rules, but is
379        now correct.]
380    
381    6.  There was a bug in the handling of #-introduced comments, recognized when
382        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
383        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
384        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
385        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
386        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
387        places in pcre_compile().
388    
389    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
390        comments when looking ahead for named forward references to subpatterns,
391        the only newline sequence it recognized was NL. It now handles newlines
392        according to the set newline convention.
393    
394    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
395        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
396        cater for a lack of strerror(). These oversights have been fixed.
397    
398    9.  Added --match-limit and --recursion-limit to pcregrep.
399    
400    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
401    
402    11. When the -o option was used, pcregrep was setting a return code of 1, even
403        when matches were found, and --line-buffered was not being honoured.
404    
405    12. Added an optional parentheses number to the -o and --only-matching options
406        of pcregrep.
407    
408    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
409        can match an empty string. The code to do it in pcretest and pcredemo
410        needed fixing:
411    
412        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
413            only one byte after an empty string match just before CRLF (this case
414            just got forgotten; "any" and "anycrlf" were OK).
415    
416        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
417            mode when an empty string match preceded an ASCII character followed by
418            a non-ASCII character. (The code for advancing by one character rather
419            than one byte was nonsense.)
420    
421        (c) The pcredemo.c sample program did not have any code at all to handle
422            the cases when CRLF is a valid newline sequence.
423    
424    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
425        as a starting offset was within the subject string. There is now a new
426        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
427        negative or greater than the length of the string. In order to test this,
428        pcretest is extended to allow the setting of negative starting offsets.
429    
430    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
431        starting offset points to the beginning of a UTF-8 character was
432        unnecessarily clumsy. I tidied it up.
433    
434    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
435        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
436    
437    17. Nobody had reported that the --include_dir option, which was added in
438        release 7.7 should have been called --include-dir (hyphen, not underscore)
439        for compatibility with GNU grep. I have changed it to --include-dir, but
440        left --include_dir as an undocumented synonym, and the same for
441        --exclude-dir, though that is not available in GNU grep, at least as of
442        release 2.5.4.
443    
444    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
445        characters from a string of bytes) have been redefined so as not to use
446        loops, in order to improve performance in some environments. At the same
447        time, I abstracted some of the common code into auxiliary macros to save
448        repetition (this should not affect the compiled code).
449    
450    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
451        compile-time error is now given if \c is not followed by an ASCII
452        character, that is, a byte less than 128. (In EBCDIC mode, the code is
453        different, and any byte value is allowed.)
454    
455    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
456        START_OPTIMIZE option, which is now allowed at compile time - but just
457        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
458        to pcregrep and other applications that have no direct access to PCRE
459        options. The new /Y option in pcretest sets this option when calling
460        pcre_compile().
461    
462    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
463        back references. Groups containing recursive back references were forced to
464        be atomic by that change, but in the case of named groups, the amount of
465        memory required was incorrectly computed, leading to "Failed: internal
466        error: code overflow". This has been fixed.
467    
468    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
469        pcretest.c, to avoid build problems in some Borland environments.
470    
471    
472    Version 8.10 25-Jun-2010
473    ------------------------
474    
475    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
476        THEN.
477    
478    2.  (*ACCEPT) was not working when inside an atomic group.
479    
480    3.  Inside a character class, \B is treated as a literal by default, but
481        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
482        causes the error). The code is unchanged, but I tidied the documentation.
483    
484    4.  Inside a character class, PCRE always treated \R and \X as literals,
485        whereas Perl faults them if its -w option is set. I have changed PCRE so
486        that it faults them when PCRE_EXTRA is set.
487    
488    5.  Added support for \N, which always matches any character other than
489        newline. (It is the same as "." when PCRE_DOTALL is not set.)
490    
491    6.  When compiling pcregrep with newer versions of gcc which may have
492        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
493        declared with attribute warn_unused_result" were given. Just casting the
494        result to (void) does not stop the warnings; a more elaborate fudge is
495        needed. I've used a macro to implement this.
496    
497    7.  Minor change to pcretest.c to avoid a compiler warning.
498    
499    8.  Added four artifical Unicode properties to help with an option to make
500        \s etc use properties (see next item). The new properties are: Xan
501        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
502    
503    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
504        use Unicode properties. (*UCP) at the start of a pattern can be used to set
505        this option. Modified pcretest to add /W to test this facility. Added
506        REG_UCP to make it available via the POSIX interface.
507    
508    10. Added --line-buffered to pcregrep.
509    
510    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
511        studied, and the match started with a letter with a code point greater than
512        127 whose first byte was different to the first byte of the other case of
513        the letter, the other case of this starting letter was not recognized
514        (#976).
515    
516    12. If a pattern that was studied started with a repeated Unicode property
517        test, for example, \p{Nd}+, there was the theoretical possibility of
518        setting up an incorrect bitmap of starting bytes, but fortunately it could
519        not have actually happened in practice until change 8 above was made (it
520        added property types that matched character-matching opcodes).
521    
522    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
523        possible starting bytes for non-anchored patterns.
524    
525    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
526        \R, and also a number of cases that involve Unicode properties, both
527        explicit and implicit when PCRE_UCP is set.
528    
529    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
530        input, it could crash or give wrong results if characters with values
531        greater than 0xc0 were present in the subject string. (Detail: it assumed
532        UTF-8 input when processing these items.)
533    
534    16. Added a lot of (int) casts to avoid compiler warnings in systems where
535        size_t is 64-bit (#991).
536    
537    17. Added a check for running out of memory when PCRE is compiled with
538        --disable-stack-for-recursion (#990).
539    
540    18. If the last data line in a file for pcretest does not have a newline on
541        the end, a newline was missing in the output.
542    
543    19. The default pcre_chartables.c file recognizes only ASCII characters (values
544        less than 128) in its various bitmaps. However, there is a facility for
545        generating tables according to the current locale when PCRE is compiled. It
546        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
547        characters, are recognized by isspace() and therefore were getting set in
548        these tables, and indeed these tables seem to approximate to ISO 8859. This
549        caused a problem in UTF-8 mode when pcre_study() was used to create a list
550        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
551        which of course cannot start UTF-8 characters. I have changed the code so
552        that only real ASCII characters (less than 128) and the correct starting
553        bytes for UTF-8 encodings are set for characters greater than 127 when in
554        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
555        altogether.)
556    
557    20. Added the /T option to pcretest so as to be able to run tests with non-
558        standard character tables, thus making it possible to include the tests
559        used for 19 above in the standard set of tests.
560    
561    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
562        reference to a subpattern the other side of a comment that contains an
563        opening parenthesis caused either an internal compiling error, or a
564        reference to the wrong subpattern.
565    
566    
567    Version 8.02 19-Mar-2010
568    ------------------------
569    
570    1.  The Unicode data tables have been updated to Unicode 5.2.0.
571    
572    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
573        configured.
574    
575    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
576        original author of that file, following a query about its status.
577    
578    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
579        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
580    
581    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
582        quantifier applied to a forward-referencing subroutine call, could compile
583        incorrect code or give the error "internal error: previously-checked
584        referenced subpattern not found".
585    
586    6.  Both MS Visual Studio and Symbian OS have problems with initializing
587        variables to point to external functions. For these systems, therefore,
588        pcre_malloc etc. are now initialized to local functions that call the
589        relevant global functions.
590    
591    7.  There were two entries missing in the vectors called coptable and poptable
592        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
593        I've fixed the data, and added a kludgy way of testing at compile time that
594        the lengths are correct (equal to the number of opcodes).
595    
596    8.  Following on from 7, I added a similar kludge to check the length of the
597        eint vector in pcreposix.c.
598    
599    9.  Error texts for pcre_compile() are held as one long string to avoid too
600        much relocation at load time. To find a text, the string is searched,
601        counting zeros. There was no check for running off the end of the string,
602        which could happen if a new error number was added without updating the
603        string.
604    
605    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
606    
607    11. \K was not working if it appeared in an atomic group or in a group that
608        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
609        \K is "not well defined" if used in an assertion. PCRE now accepts it if
610        the assertion is positive, but not if it is negative.
611    
612    12. Change 11 fortuitously reduced the size of the stack frame used in the
613        "match()" function of pcre_exec.c by one pointer. Forthcoming
614        implementation of support for (*MARK) will need an extra pointer on the
615        stack; I have reserved it now, so that the stack frame size does not
616        decrease.
617    
618    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
619        item in branch that calls a recursion is a subroutine call - as in the
620        second branch in the above example - was incorrectly given the compile-
621        time error "recursive call could loop indefinitely" because pcre_compile()
622        was not correctly checking the subroutine for matching a non-empty string.
623    
624    14. The checks for overrunning compiling workspace could trigger after an
625        overrun had occurred. This is a "should never occur" error, but it can be
626        triggered by pathological patterns such as hundreds of nested parentheses.
627        The checks now trigger 100 bytes before the end of the workspace.
628    
629    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
630    
631    
632    Version 8.01 19-Jan-2010
633    ------------------------
634    
635    1.  If a pattern contained a conditional subpattern with only one branch (in
636        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
637        computed the wrong minimum data length (which is of course zero for such
638        subpatterns). This could cause incorrect "no match" results.
639    
640    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
641        the pattern is reset in the first branch, pcre_compile() failed with
642        "internal error: code overflow at offset...". This happened only when
643        the reset was to the original external option setting. (An optimization
644        abstracts leading options settings into an external setting, which was the
645        cause of this.)
646    
647    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
648        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
649        assertion pattern did not match (meaning that the assertion was true), it
650        was incorrectly treated as false if the SKIP had been reached during the
651        matching. This also applied to assertions used as conditions.
652    
653    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
654        assertion subpattern, including such a pattern used as a condition,
655        unpredictable results occurred, instead of the error return
656        PCRE_ERROR_DFA_UITEM.
657    
658    5.  The C++ GlobalReplace function was not working like Perl for the special
659        situation when an empty string is matched. It now does the fancy magic
660        stuff that is necessary.
661    
662    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
663        removed. (These were left over from very, very early versions of PCRE.)
664    
665    7.  Some cosmetic changes to the code to make life easier when compiling it
666        as part of something else:
667    
668        (a) Change DEBUG to PCRE_DEBUG.
669    
670        (b) In pcre_compile(), rename the member of the "branch_chain" structure
671            called "current" as "current_branch", to prevent a collision with the
672            Linux macro when compiled as a kernel module.
673    
674        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
675            prevent a collision with the Linux macro when compiled as a kernel
676            module.
677    
678    8.  In pcre_compile() there are some checks for integer overflows that used to
679        cast potentially large values to (double). This has been changed to that
680        when building, a check for int64_t is made, and if it is found, it is used
681        instead, thus avoiding the use of floating point arithmetic. (There is no
682        other use of FP in PCRE.) If int64_t is not found, the fallback is to
683        double.
684    
685    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
686        2005 (difference between two addresses compared to an unsigned value).
687    
688    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
689        custom one, because of the following reported problem in Windows:
690    
691          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
692              under Win32.
693          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
694              therefore missing the function definition.
695          - The compiler thus generates a "C" signature for the test function.
696          - The linker fails to find the "C" function.
697          - PCRE fails to configure if asked to do so against libbz2.
698    
699    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
700        messages were output:
701    
702          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
703          rerunning libtoolize, to keep the correct libtool macros in-tree.
704          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
705    
706        I have done both of these things.
707    
708    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
709        most of the time, it *can* run out if it is given a pattern that contains a
710        runaway infinite recursion. I updated the discussion in the pcrestack man
711        page.
712    
713    13. Now that we have gone to the x.xx style of version numbers, the minor
714        version may start with zero. Using 08 or 09 is a bad idea because users
715        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
716        interpreted as invalid octal numbers. I've updated the previous comment in
717        configure.ac, and also added a check that gives an error if 08 or 09 are
718        used.
719    
720    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
721        causing partial matching to fail when the end of the subject matched \W
722        in a UTF-8 pattern where \W was quantified with a minimum of 3.
723    
724    15. There were some discrepancies between the declarations in pcre_internal.h
725        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
726        their definitions. The declarations used "const uschar *" and the
727        definitions used USPTR. Even though USPTR is normally defined as "const
728        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
729        reported that: "This difference in casting confuses some C++ compilers, for
730        example, SunCC recognizes above declarations as different functions and
731        generates broken code for hbpcre." I have changed the declarations to use
732        USPTR.
733    
734    16. GNU libtool is named differently on some systems. The autogen.sh script now
735        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
736        (FreeBSD).
737    
738    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
739        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
740        comment: "Figure out how to create a longlong from a string: strtoll and
741        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
742        instance, but it only takes 2 args instead of 3!"
743    
744    18. A subtle bug concerned with back references has been fixed by a change of
745        specification, with a corresponding code fix. A pattern such as
746        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
747        refers, was giving matches when it shouldn't. For example, xa=xaaa would
748        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
749        same bug. Such groups have to be quantified to be useful, or contained
750        inside another quantified group. (If there's no repetition, the reference
751        can never match.) The problem arises because, having left the group and
752        moved on to the rest of the pattern, a later failure that backtracks into
753        the group uses the captured value from the final iteration of the group
754        rather than the correct earlier one. I have fixed this in PCRE by forcing
755        any group that contains a reference to itself to be an atomic group; that
756        is, there cannot be any backtracking into it once it has completed. This is
757        similar to recursive and subroutine calls.
758    
759    
760    Version 8.00 19-Oct-09
761  ----------------------  ----------------------
762    
763  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
764      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
765      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
766      error.      error.
767    
768  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
769      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
770      in a Windows environment.      in a Windows environment.
771    
772  3.  The pcregrep --count option prints the count for each file even when it is  3.  The pcregrep --count option prints the count for each file even when it is
773      zero, as does GNU grep. However, pcregrep was also printing all files when      zero, as does GNU grep. However, pcregrep was also printing all files when
774      --files-with-matches was added. Now, when both options are given, it prints      --files-with-matches was added. Now, when both options are given, it prints
775      counts only for those files that have at least one match. (GNU grep just      counts only for those files that have at least one match. (GNU grep just
776      prints the file name in this circumstance, but including the count seems      prints the file name in this circumstance, but including the count seems
777      more useful - otherwise, why use --count?) Also ensured that the      more useful - otherwise, why use --count?) Also ensured that the
778      combination -clh just lists non-zero counts, with no names.      combination -clh just lists non-zero counts, with no names.
779    
780  4.  The long form of the pcregrep -F option was incorrectly implemented as  4.  The long form of the pcregrep -F option was incorrectly implemented as
781      --fixed_strings instead of --fixed-strings. This is an incompatible change,      --fixed_strings instead of --fixed-strings. This is an incompatible change,
782      but it seems right to fix it, and I didn't think it was worth preserving      but it seems right to fix it, and I didn't think it was worth preserving
783      the old behaviour.      the old behaviour.
784    
785  5.  The command line items --regex=pattern and --regexp=pattern were not  5.  The command line items --regex=pattern and --regexp=pattern were not
786      recognized by pcregrep, which required --regex pattern or --regexp pattern      recognized by pcregrep, which required --regex pattern or --regexp pattern
787      (with a space rather than an '='). The man page documented the '=' forms,      (with a space rather than an '='). The man page documented the '=' forms,
788      which are compatible with GNU grep; these now work.      which are compatible with GNU grep; these now work.
789    
790  6.  No libpcreposix.pc file was created for pkg-config; there was just  6.  No libpcreposix.pc file was created for pkg-config; there was just
791      libpcre.pc and libpcrecpp.pc. The omission has been rectified.      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
792    
793  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
794      when UCP support is not needed, by modifying the Python script that      when UCP support is not needed, by modifying the Python script that
795      generates it from Unicode data files. This should not matter if the module      generates it from Unicode data files. This should not matter if the module
796      is correctly used as a library, but I received one complaint about 50K of      is correctly used as a library, but I received one complaint about 50K of
797      unwanted data. My guess is that the person linked everything into his      unwanted data. My guess is that the person linked everything into his
798      program rather than using a library. Anyway, it does no harm.      program rather than using a library. Anyway, it does no harm.
799    
800  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
801      was a minimum greater than 1 for a wide character in a possessive      was a minimum greater than 1 for a wide character in a possessive
802      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
803      which had an unlimited repeat of a nested, fixed maximum repeat of a wide      which had an unlimited repeat of a nested, fixed maximum repeat of a wide
804      character. Chaos in the form of incorrect output or a compiling loop could      character. Chaos in the form of incorrect output or a compiling loop could
805      result.      result.
806    
807  9.  The restrictions on what a pattern can contain when partial matching is  9.  The restrictions on what a pattern can contain when partial matching is
808      requested for pcre_exec() have been removed. All patterns can now be      requested for pcre_exec() have been removed. All patterns can now be
809      partially matched by this function. In addition, if there are at least two      partially matched by this function. In addition, if there are at least two
810      slots in the offset vector, the offset of the earliest inspected character      slots in the offset vector, the offset of the earliest inspected character
811      for the match and the offset of the end of the subject are set in them when      for the match and the offset of the end of the subject are set in them when
812      PCRE_ERROR_PARTIAL is returned.      PCRE_ERROR_PARTIAL is returned.
813    
814  10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is  10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
815      synonymous with PCRE_PARTIAL, for backwards compatibility, and      synonymous with PCRE_PARTIAL, for backwards compatibility, and
816      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
817      and may be more useful for multi-segment matching, especially with      and may be more useful for multi-segment matching.
818      pcre_exec().  
819    11. Partial matching with pcre_exec() is now more intuitive. A partial match
820  11. Partial matching with pcre_exec() is now more intuitive. A partial match      used to be given if ever the end of the subject was reached; now it is
821      used to be given if ever the end of the subject was reached; now it is      given only if matching could not proceed because another character was
822      given only if matching could not proceed because another character was      needed. This makes a difference in some odd cases such as Z(*FAIL) with the
823      needed. This makes a difference in some odd cases such as Z(*FAIL) with the      string "Z", which now yields "no match" instead of "partial match". In the
824      string "Z", which now yields "no match" instead of "partial match". In the      case of pcre_dfa_exec(), "no match" is given if every matching path for the
825      case of pcre_dfa_exec(), "no match" is given if every matching path for the      final character ended with (*FAIL).
826      final character ended with (*FAIL).  
   
827  12. Restarting a match using pcre_dfa_exec() after a partial match did not work  12. Restarting a match using pcre_dfa_exec() after a partial match did not work
828      if the pattern had a "must contain" character that was already found in the      if the pattern had a "must contain" character that was already found in the
829      earlier partial match, unless partial matching was again requested. For      earlier partial match, unless partial matching was again requested. For
830      example, with the pattern /dog.(body)?/, the "must contain" character is      example, with the pattern /dog.(body)?/, the "must contain" character is
831      "g". If the first part-match was for the string "dog", restarting with      "g". If the first part-match was for the string "dog", restarting with
832      "sbody" failed. This bug has been fixed.      "sbody" failed. This bug has been fixed.
833    
834  13. The string returned by pcre_dfa_exec() after a partial match has been  13. The string returned by pcre_dfa_exec() after a partial match has been
835      changed so that it starts at the first inspected character rather than the      changed so that it starts at the first inspected character rather than the
836      first character of the match. This makes a difference only if the pattern      first character of the match. This makes a difference only if the pattern
837      starts with a lookbehind assertion or \b or \B (\K is not supported by      starts with a lookbehind assertion or \b or \B (\K is not supported by
838      pcre_dfa_exec()). It's an incompatible change, but it makes the two      pcre_dfa_exec()). It's an incompatible change, but it makes the two
839      matching functions compatible, and I think it's the right thing to do.      matching functions compatible, and I think it's the right thing to do.
840    
841  14. Added a pcredemo man page, created automatically from the pcredemo.c file,  14. Added a pcredemo man page, created automatically from the pcredemo.c file,
842      so that the demonstration program is easily available in environments where      so that the demonstration program is easily available in environments where
843      PCRE has not been installed from source.      PCRE has not been installed from source.
844    
845  15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,  15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
846      libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared      libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
847      library.      library.
848    
849  16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.  16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
850      It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it      It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
851      is not the first non-POSIX option to be added. Clearly some people find      is not the first non-POSIX option to be added. Clearly some people find
852      these options useful.      these options useful.
853    
854  17. If a caller to the POSIX matching function regexec() passes a non-zero  17. If a caller to the POSIX matching function regexec() passes a non-zero
855      value for nmatch with a NULL value for pmatch, the value of      value for nmatch with a NULL value for pmatch, the value of
856      nmatch is forced to zero.      nmatch is forced to zero.
857    
858  18. RunGrepTest did not have a test for the availability of the -u option of  18. RunGrepTest did not have a test for the availability of the -u option of
859      the diff command, as RunTest does. It now checks in the same way as      the diff command, as RunTest does. It now checks in the same way as
860      RunTest, and also checks for the -b option.      RunTest, and also checks for the -b option.
861    
862  19. If an odd number of negated classes containing just a single character  19. If an odd number of negated classes containing just a single character
863      interposed, within parentheses, between a forward reference to a named      interposed, within parentheses, between a forward reference to a named
864      subpattern and the definition of the subpattern, compilation crashed with      subpattern and the definition of the subpattern, compilation crashed with
865      an internal error, complaining that it could not find the referenced      an internal error, complaining that it could not find the referenced
866      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
867      [The bug was that it was starting one character too far in when skipping      [The bug was that it was starting one character too far in when skipping
868      over the character class, thus treating the ] as data rather than      over the character class, thus treating the ] as data rather than
869      terminating the class. This meant it could skip too much.]      terminating the class. This meant it could skip too much.]
870    
871  20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the  20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
872      /g option in pcretest when the pattern contains \K, which makes it possible      /g option in pcretest when the pattern contains \K, which makes it possible
873      to have an empty string match not at the start, even when the pattern is      to have an empty string match not at the start, even when the pattern is
874      anchored. Updated pcretest and pcredemo to use this option.      anchored. Updated pcretest and pcredemo to use this option.
875    
876  21. If the maximum number of capturing subpatterns in a recursion was greater  21. If the maximum number of capturing subpatterns in a recursion was greater
877      than the maximum at the outer level, the higher number was returned, but      than the maximum at the outer level, the higher number was returned, but
878      with unset values at the outer level. The correct (outer level) value is      with unset values at the outer level. The correct (outer level) value is
879      now given.      now given.
880    
881  22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of  22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
882      PCRE did not set those parentheses (unlike Perl). I have now found a way to      PCRE did not set those parentheses (unlike Perl). I have now found a way to
883      make it do so. The string so far is captured, making this feature      make it do so. The string so far is captured, making this feature
884      compatible with Perl.      compatible with Perl.
885    
886    23. The tests have been re-organized, adding tests 11 and 12, to make it
887        possible to check the Perl 5.10 features against Perl 5.10.
888    
889    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
890        pattern matches a fixed length string. PCRE did not allow this; now it
891        does. Neither allows recursion.
892    
893    25. I finally figured out how to implement a request to provide the minimum
894        length of subject string that was needed in order to match a given pattern.
895        (It was back references and recursion that I had previously got hung up
896        on.) This code has now been added to pcre_study(); it finds a lower bound
897        to the length of subject needed. It is not necessarily the greatest lower
898        bound, but using it to avoid searching strings that are too short does give
899        some useful speed-ups. The value is available to calling programs via
900        pcre_fullinfo().
901    
902    26. While implementing 25, I discovered to my embarrassment that pcretest had
903        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
904        study optimizations had never been tested with that matching function.
905        Oops. What is worse, even when it was passed study data, there was a bug in
906        pcre_dfa_exec() that meant it never actually used it. Double oops. There
907        were also very few tests of studied patterns with pcre_dfa_exec().
908    
909    27. If (?| is used to create subpatterns with duplicate numbers, they are now
910        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
911        on the other side of the coin, they are no longer allowed to have different
912        names, because these cannot be distinguished in PCRE, and this has caused
913        confusion. (This is a difference from Perl.)
914    
915    28. When duplicate subpattern names are present (necessarily with different
916        numbers, as required by 27 above), and a test is made by name in a
917        conditional pattern, either for a subpattern having been matched, or for
918        recursion in such a pattern, all the associated numbered subpatterns are
919        tested, and the overall condition is true if the condition is true for any
920        one of them. This is the way Perl works, and is also more like the way
921        testing by number works.
922    
923    
924  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
925  ---------------------  ---------------------

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