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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.10 03 May-2010
5    ------------------------
6    
7    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
8        THEN.
9    
10    2.  (*ACCEPT) was not working when inside an atomic group.
11    
12    3.  Inside a character class, \B is treated as a literal by default, but
13        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
14        causes the error). The code is unchanged, but I tidied the documentation.
15    
16    4.  Inside a character class, PCRE always treated \R and \X as literals,
17        whereas Perl faults them if its -w option is set. I have changed PCRE so
18        that it faults them when PCRE_EXTRA is set.
19    
20    5.  Added support for \N, which always matches any character other than
21        newline. (It is the same as "." when PCRE_DOTALL is not set.)
22    
23    6.  When compiling pcregrep with newer versions of gcc which may have
24        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
25        declared with attribute warn_unused_result" were given. Just casting the
26        result to (void) does not stop the warnings; a more elaborate fudge is
27        needed. I've used a macro to implement this.
28    
29    7.  Minor change to pcretest.c to avoid a compiler warning.
30    
31    
32    Version 8.02 19-Mar-2010
33    ------------------------
34    
35    1.  The Unicode data tables have been updated to Unicode 5.2.0.
36    
37    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
38        configured.
39    
40    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
41        original author of that file, following a query about its status.
42    
43    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
44        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
45    
46    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
47        quantifier applied to a forward-referencing subroutine call, could compile
48        incorrect code or give the error "internal error: previously-checked
49        referenced subpattern not found".
50    
51    6.  Both MS Visual Studio and Symbian OS have problems with initializing
52        variables to point to external functions. For these systems, therefore,
53        pcre_malloc etc. are now initialized to local functions that call the
54        relevant global functions.
55    
56    7.  There were two entries missing in the vectors called coptable and poptable
57        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
58        I've fixed the data, and added a kludgy way of testing at compile time that
59        the lengths are correct (equal to the number of opcodes).
60    
61    8.  Following on from 7, I added a similar kludge to check the length of the
62        eint vector in pcreposix.c.
63    
64    9.  Error texts for pcre_compile() are held as one long string to avoid too
65        much relocation at load time. To find a text, the string is searched,
66        counting zeros. There was no check for running off the end of the string,
67        which could happen if a new error number was added without updating the
68        string.
69    
70    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
71    
72    11. \K was not working if it appeared in an atomic group or in a group that
73        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
74        \K is "not well defined" if used in an assertion. PCRE now accepts it if
75        the assertion is positive, but not if it is negative.
76    
77    12. Change 11 fortuitously reduced the size of the stack frame used in the
78        "match()" function of pcre_exec.c by one pointer. Forthcoming
79        implementation of support for (*MARK) will need an extra pointer on the
80        stack; I have reserved it now, so that the stack frame size does not
81        decrease.
82    
83    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
84        item in branch that calls a recursion is a subroutine call - as in the
85        second branch in the above example - was incorrectly given the compile-
86        time error "recursive call could loop indefinitely" because pcre_compile()
87        was not correctly checking the subroutine for matching a non-empty string.
88    
89    14. The checks for overrunning compiling workspace could trigger after an
90        overrun had occurred. This is a "should never occur" error, but it can be
91        triggered by pathological patterns such as hundreds of nested parentheses.
92        The checks now trigger 100 bytes before the end of the workspace.
93    
94    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
95    
96    
97    Version 8.01 19-Jan-2010
98    ------------------------
99    
100    1.  If a pattern contained a conditional subpattern with only one branch (in
101        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
102        computed the wrong minimum data length (which is of course zero for such
103        subpatterns). This could cause incorrect "no match" results.
104    
105    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
106        the pattern is reset in the first branch, pcre_compile() failed with
107        "internal error: code overflow at offset...". This happened only when
108        the reset was to the original external option setting. (An optimization
109        abstracts leading options settings into an external setting, which was the
110        cause of this.)
111    
112    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
113        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
114        assertion pattern did not match (meaning that the assertion was true), it
115        was incorrectly treated as false if the SKIP had been reached during the
116        matching. This also applied to assertions used as conditions.
117    
118    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
119        assertion subpattern, including such a pattern used as a condition,
120        unpredictable results occurred, instead of the error return
121        PCRE_ERROR_DFA_UITEM.
122    
123    5.  The C++ GlobalReplace function was not working like Perl for the special
124        situation when an empty string is matched. It now does the fancy magic
125        stuff that is necessary.
126    
127    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
128        removed. (These were left over from very, very early versions of PCRE.)
129    
130    7.  Some cosmetic changes to the code to make life easier when compiling it
131        as part of something else:
132    
133        (a) Change DEBUG to PCRE_DEBUG.
134    
135        (b) In pcre_compile(), rename the member of the "branch_chain" structure
136            called "current" as "current_branch", to prevent a collision with the
137            Linux macro when compiled as a kernel module.
138    
139        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
140            prevent a collision with the Linux macro when compiled as a kernel
141            module.
142    
143    8.  In pcre_compile() there are some checks for integer overflows that used to
144        cast potentially large values to (double). This has been changed to that
145        when building, a check for int64_t is made, and if it is found, it is used
146        instead, thus avoiding the use of floating point arithmetic. (There is no
147        other use of FP in PCRE.) If int64_t is not found, the fallback is to
148        double.
149    
150    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
151        2005 (difference between two addresses compared to an unsigned value).
152    
153    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
154        custom one, because of the following reported problem in Windows:
155    
156          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
157              under Win32.
158          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
159              therefore missing the function definition.
160          - The compiler thus generates a "C" signature for the test function.
161          - The linker fails to find the "C" function.
162          - PCRE fails to configure if asked to do so against libbz2.
163    
164    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
165        messages were output:
166    
167          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
168          rerunning libtoolize, to keep the correct libtool macros in-tree.
169          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
170    
171        I have done both of these things.
172    
173    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
174        most of the time, it *can* run out if it is given a pattern that contains a
175        runaway infinite recursion. I updated the discussion in the pcrestack man
176        page.
177    
178    13. Now that we have gone to the x.xx style of version numbers, the minor
179        version may start with zero. Using 08 or 09 is a bad idea because users
180        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
181        interpreted as invalid octal numbers. I've updated the previous comment in
182        configure.ac, and also added a check that gives an error if 08 or 09 are
183        used.
184    
185    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
186        causing partial matching to fail when the end of the subject matched \W
187        in a UTF-8 pattern where \W was quantified with a minimum of 3.
188    
189    15. There were some discrepancies between the declarations in pcre_internal.h
190        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
191        their definitions. The declarations used "const uschar *" and the
192        definitions used USPTR. Even though USPTR is normally defined as "const
193        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
194        reported that: "This difference in casting confuses some C++ compilers, for
195        example, SunCC recognizes above declarations as different functions and
196        generates broken code for hbpcre." I have changed the declarations to use
197        USPTR.
198    
199    16. GNU libtool is named differently on some systems. The autogen.sh script now
200        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
201        (FreeBSD).
202    
203    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
204        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
205        comment: "Figure out how to create a longlong from a string: strtoll and
206        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
207        instance, but it only takes 2 args instead of 3!"
208    
209    18. A subtle bug concerned with back references has been fixed by a change of
210        specification, with a corresponding code fix. A pattern such as
211        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
212        refers, was giving matches when it shouldn't. For example, xa=xaaa would
213        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
214        same bug. Such groups have to be quantified to be useful, or contained
215        inside another quantified group. (If there's no repetition, the reference
216        can never match.) The problem arises because, having left the group and
217        moved on to the rest of the pattern, a later failure that backtracks into
218        the group uses the captured value from the final iteration of the group
219        rather than the correct earlier one. I have fixed this in PCRE by forcing
220        any group that contains a reference to itself to be an atomic group; that
221        is, there cannot be any backtracking into it once it has completed. This is
222        similar to recursive and subroutine calls.
223    
224    
225    Version 8.00 19-Oct-09
226  ----------------------  ----------------------
227    
228  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
229      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
230      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
231      error.      error.
232    
233  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,
234      "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
235      in a Windows environment.      in a Windows environment.
236    
237  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
238      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
239      --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
240      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
241      prints the file name in this circumstance, but including the count seems      prints the file name in this circumstance, but including the count seems
242      more useful - otherwise, why use --count?) Also ensured that the      more useful - otherwise, why use --count?) Also ensured that the
243      combination -clh just lists non-zero counts, with no names.      combination -clh just lists non-zero counts, with no names.
244    
245  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
246      --fixed_strings instead of --fixed-strings. This is an incompatible change,      --fixed_strings instead of --fixed-strings. This is an incompatible change,
247      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
248      the old behaviour.      the old behaviour.
249    
250  5.  The command line items --regex=pattern and --regexp=pattern were not  5.  The command line items --regex=pattern and --regexp=pattern were not
251      recognized by pcregrep, which required --regex pattern or --regexp pattern      recognized by pcregrep, which required --regex pattern or --regexp pattern
252      (with a space rather than an '='). The man page documented the '=' forms,      (with a space rather than an '='). The man page documented the '=' forms,
253      which are compatible with GNU grep; these now work.      which are compatible with GNU grep; these now work.
254    
255  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
256      libpcre.pc and libpcrecpp.pc. The omission has been rectified.      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
257    
258  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
259      when UCP support is not needed, by modifying the Python script that      when UCP support is not needed, by modifying the Python script that
260      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
261      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
262      unwanted data. My guess is that the person linked everything into his      unwanted data. My guess is that the person linked everything into his
263      program rather than using a library. Anyway, it does no harm.      program rather than using a library. Anyway, it does no harm.
264    
265  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
266      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
267      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
268      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
269      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
270      result.      result.
271    
272  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
273      requested for pcre_exec() have been removed. All patterns can now be      requested for pcre_exec() have been removed. All patterns can now be
274      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
275      slots in the offset vector, the offset of the earliest inspected character      slots in the offset vector, the offset of the earliest inspected character
276      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
277      PCRE_ERROR_PARTIAL is returned.      PCRE_ERROR_PARTIAL is returned.
278    
279  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
280      synonymous with PCRE_PARTIAL, for backwards compatibility, and      synonymous with PCRE_PARTIAL, for backwards compatibility, and
281      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,
282      and may be more useful for multi-segment matching, especially with      and may be more useful for multi-segment matching.
283      pcre_exec().  
284    11. Partial matching with pcre_exec() is now more intuitive. A partial match
285  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
286      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
287      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
288      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
289      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
290      case of pcre_dfa_exec(), "no match" is given if every matching path for the      final character ended with (*FAIL).
291      final character ended with (*FAIL).  
   
292  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
293      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
294      earlier partial match, unless partial matching was again requested. For      earlier partial match, unless partial matching was again requested. For
295      example, with the pattern /dog.(body)?/, the "must contain" character is      example, with the pattern /dog.(body)?/, the "must contain" character is
296      "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
297      "sbody" failed. This bug has been fixed.      "sbody" failed. This bug has been fixed.
298    
299  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
300      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
301      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
302      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
303      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
304      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.
305    
306  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,
307      so that the demonstration program is easily available in environments where      so that the demonstration program is easily available in environments where
308      PCRE has not been installed from source.      PCRE has not been installed from source.
309    
310  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,
311      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
312      library.      library.
313    
314  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.
315      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
316      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
317      these options useful.      these options useful.
318    
319  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
320      value for nmatch with a NULL value for pmatch, the value of      value for nmatch with a NULL value for pmatch, the value of
321      nmatch is forced to zero.      nmatch is forced to zero.
322    
323  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
324      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
325      RunTest, and also checks for the -b option.      RunTest, and also checks for the -b option.
326    
327  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
328      interposed, within parentheses, between a forward reference to a named      interposed, within parentheses, between a forward reference to a named
329      subpattern and the definition of the subpattern, compilation crashed with      subpattern and the definition of the subpattern, compilation crashed with
330      an internal error, complaining that it could not find the referenced      an internal error, complaining that it could not find the referenced
331      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.      subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
332      [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
333      over the character class, thus treating the ] as data rather than      over the character class, thus treating the ] as data rather than
334      terminating the class. This meant it could skip too much.]      terminating the class. This meant it could skip too much.]
335    
336  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
337      /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
338      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
339      anchored. Updated pcretest and pcredemo to use this option.      anchored. Updated pcretest and pcredemo to use this option.
340    
341  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
342      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
343      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
344      now given.      now given.
345    
346  22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of  22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
347      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
348      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
349      compatible with Perl.      compatible with Perl.
350    
351  23. The tests have been re-organized, adding tests 11 and 12, to make it  23. The tests have been re-organized, adding tests 11 and 12, to make it
352      possible to check the Perl 5.10 features against Perl 5.10.      possible to check the Perl 5.10 features against Perl 5.10.
353    
354  24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine  24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
355      pattern matches a fixed length string. PCRE did not allow this; now it      pattern matches a fixed length string. PCRE did not allow this; now it
356      does. Neither allows recursion.      does. Neither allows recursion.
357    
358  25. I finally figured out how to implement a request to provide the minimum  25. I finally figured out how to implement a request to provide the minimum
359      length of subject string that was needed in order to match a given pattern.      length of subject string that was needed in order to match a given pattern.
360      (It was back references and recursion that I had previously got hung up      (It was back references and recursion that I had previously got hung up
361      on.) This code has now been added to pcre_study(); it finds a lower bound      on.) This code has now been added to pcre_study(); it finds a lower bound
362      to the length of subject needed. It is not necessarily the greatest lower      to the length of subject needed. It is not necessarily the greatest lower
363      bound, but using it to avoid searching strings that are too short does give      bound, but using it to avoid searching strings that are too short does give
364      some useful speed-ups. The value is available to calling programs via      some useful speed-ups. The value is available to calling programs via
365      pcre_fullinfo().      pcre_fullinfo().
366    
367  26. While implementing 25, I discovered to my embarrassment that pcretest had  26. While implementing 25, I discovered to my embarrassment that pcretest had
368      not been passing the result of pcre_study() to pcre_dfa_exec(), so the      not been passing the result of pcre_study() to pcre_dfa_exec(), so the
369      study optimizations had never been tested with that matching function.      study optimizations had never been tested with that matching function.
370      Oops. What is worse, even when it was passed study data, there was a bug in      Oops. What is worse, even when it was passed study data, there was a bug in
371      pcre_dfa_exec() that meant it never actually used it. Double oops. There      pcre_dfa_exec() that meant it never actually used it. Double oops. There
372      were also very few tests of studied patterns with pcre_dfa_exec().      were also very few tests of studied patterns with pcre_dfa_exec().
373    
374  27. If (?| is used to create subpatterns with duplicate numbers, they are now  27. If (?| is used to create subpatterns with duplicate numbers, they are now
375      allowed to have the same name, even if PCRE_DUPNAMES is not set. However,      allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
376      on the other side of the coin, they are no longer allowed to have different      on the other side of the coin, they are no longer allowed to have different
377      names, because these cannot be distinguished in PCRE, and this has caused      names, because these cannot be distinguished in PCRE, and this has caused
378      confusion. (This is a difference from Perl.)      confusion. (This is a difference from Perl.)
379    
380  28. When duplicate subpattern names are present (necessarily with different  28. When duplicate subpattern names are present (necessarily with different
381      numbers, as required by 27 above), and a test is made by name in a      numbers, as required by 27 above), and a test is made by name in a
382      conditional pattern, either for a subpattern having been matched, or for      conditional pattern, either for a subpattern having been matched, or for
383      recursion in such a pattern, all the associated numbered subpatterns are      recursion in such a pattern, all the associated numbered subpatterns are
384      tested, and the overall condition is true if the condition is true for any      tested, and the overall condition is true if the condition is true for any
385      one of them. This is the way Perl works, and is also more like the way      one of them. This is the way Perl works, and is also more like the way
386      testing by number works.      testing by number works.
387    
388    
389  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
390  ---------------------  ---------------------

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