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revision 89 by nigel, Sat Feb 24 21:41:27 2007 UTC revision 143 by ph10, Mon Apr 2 10:08:14 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 12-Mar-07
5    ---------------------
6    
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
11    
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
18    
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
27    
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
32    
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files
36        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
37    
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
41    
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
44    
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
51    
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
57    
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
62    
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
64    
65        (a) It was defining its arguments as char * instead of void *.
66    
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
69    
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
73    
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
80    
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
83    
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
89    
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
97    
98    13. Some tidying changes to the testing mechanism:
99    
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
105    
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
115    
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
118    
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
125    
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
129    
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
132    
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string at the end of a line did not allow for this case. They now check for
137        it specially.
138    
139    
140    Version 7.0 19-Dec-06
141    ---------------------
142    
143     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
144        moving to gcc 4.1.1.
145    
146     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
147        sys/time.h, which is documented as needed for this function. It doesn't
148        seem to matter on Linux, but it showed up on some releases of OS X.
149    
150     3. It seems that there are systems where bytes whose values are greater than
151        127 match isprint() in the "C" locale. The "C" locale should be the
152        default when a C program starts up. In most systems, only ASCII printing
153        characters match isprint(). This difference caused the output from pcretest
154        to vary, making some of the tests fail. I have changed pcretest so that:
155    
156        (a) When it is outputting text in the compiled version of a pattern, bytes
157            other than 32-126 are always shown as hex escapes.
158    
159        (b) When it is outputting text that is a matched part of a subject string,
160            it does the same, unless a different locale has been set for the match
161            (using the /L modifier). In this case, it uses isprint() to decide.
162    
163     4. Fixed a major bug that caused incorrect computation of the amount of memory
164        required for a compiled pattern when options that changed within the
165        pattern affected the logic of the preliminary scan that determines the
166        length. The relevant options are -x, and -i in UTF-8 mode. The result was
167        that the computed length was too small. The symptoms of this bug were
168        either the PCRE error "internal error: code overflow" from pcre_compile(),
169        or a glibc crash with a message such as "pcretest: free(): invalid next
170        size (fast)". Examples of patterns that provoked this bug (shown in
171        pcretest format) are:
172    
173          /(?-x: )/x
174          /(?x)(?-x: \s*#\s*)/
175          /((?i)[\x{c0}])/8
176          /(?i:[\x{c0}])/8
177    
178        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
179        is now done differently.
180    
181     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
182        wrapper classes; (b) implement a new function in the C++ scanner that is
183        more efficient than the old way of doing things because it avoids levels of
184        recursion in the regex matching; (c) add a paragraph to the documentation
185        for the FullMatch() function.
186    
187     6. The escape sequence \n was being treated as whatever was defined as
188        "newline". Not only was this contrary to the documentation, which states
189        that \n is character 10 (hex 0A), but it also went horribly wrong when
190        "newline" was defined as CRLF. This has been fixed.
191    
192     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
193        was being set to -1 for the "end of line" case (supposedly a value that no
194        character can have). Though this value is never used (the check for end of
195        line is "zero bytes in current character"), it caused compiler complaints.
196        I've changed it to 0xffffffff.
197    
198     8. In pcre_version.c, the version string was being built by a sequence of
199        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
200        string (as it is for production releases) called a macro with an empty
201        argument. The C standard says the result of this is undefined. The gcc
202        compiler treats it as an empty string (which was what was wanted) but it is
203        reported that Visual C gives an error. The source has been hacked around to
204        avoid this problem.
205    
206     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
207        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
208        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
209        of them did).
210    
211    10. Originally, pcretest opened its input and output without "b"; then I was
212        told that "b" was needed in some environments, so it was added for release
213        5.0 to both the input and output. (It makes no difference on Unix-like
214        systems.) Later I was told that it is wrong for the input on Windows. I've
215        now abstracted the modes into two macros, to make it easier to fiddle with
216        them, and removed "b" from the input mode under Windows.
217    
218    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
219    
220    12. Added -help and --help to pcretest as an official way of being reminded
221        of the options.
222    
223    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
224        and pcrecpp.cc because they annoy compilers at high warning levels.
225    
226    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
227    
228    15. Fixed an occurrence of == in configure.ac that should have been = (shell
229        scripts are not C programs :-) and which was not noticed because it works
230        on Linux.
231    
232    16. pcretest is supposed to handle any length of pattern and data line (as one
233        line or as a continued sequence of lines) by extending its input buffer if
234        necessary. This feature was broken for very long pattern lines, leading to
235        a string of junk being passed to pcre_compile() if the pattern was longer
236        than about 50K.
237    
238    17. I have done a major re-factoring of the way pcre_compile() computes the
239        amount of memory needed for a compiled pattern. Previously, there was code
240        that made a preliminary scan of the pattern in order to do this. That was
241        OK when PCRE was new, but as the facilities have expanded, it has become
242        harder and harder to keep it in step with the real compile phase, and there
243        have been a number of bugs (see for example, 4 above). I have now found a
244        cunning way of running the real compile function in a "fake" mode that
245        enables it to compute how much memory it would need, while actually only
246        ever using a few hundred bytes of working memory and without too many
247        tests of the mode. This should make future maintenance and development
248        easier. A side effect of this work is that the limit of 200 on the nesting
249        depth of parentheses has been removed (though this was never a serious
250        limitation, I suspect). However, there is a downside: pcre_compile() now
251        runs more slowly than before (30% or more, depending on the pattern). I
252        hope this isn't a big issue. There is no effect on runtime performance.
253    
254    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
255        newline (only possible for the last line of a file) and it was a
256        pattern that set a locale (followed by /Lsomething), pcretest crashed.
257    
258    19. Added additional timing features to pcretest. (1) The -tm option now times
259        matching only, not compiling. (2) Both -t and -tm can be followed, as a
260        separate command line item, by a number that specifies the number of
261        repeats to use when timing. The default is 50000; this gives better
262        precision, but takes uncomfortably long for very large patterns.
263    
264    20. Extended pcre_study() to be more clever in cases where a branch of a
265        subpattern has no definite first character. For example, (a*|b*)[cd] would
266        previously give no result from pcre_study(). Now it recognizes that the
267        first character must be a, b, c, or d.
268    
269    21. There was an incorrect error "recursive call could loop indefinitely" if
270        a subpattern (or the entire pattern) that was being tested for matching an
271        empty string contained only one non-empty item after a nested subpattern.
272        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
273        incorrectly, because the \d was being skipped in the check.
274    
275    22. The pcretest program now has a new pattern option /B and a command line
276        option -b, which is equivalent to adding /B to every pattern. This causes
277        it to show the compiled bytecode, without the additional information that
278        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
279        is the same as /B/I).
280    
281    23. A new optimization is now able automatically to treat some sequences such
282        as a*b as a*+b. More specifically, if something simple (such as a character
283        or a simple class like \d) has an unlimited quantifier, and is followed by
284        something that cannot possibly match the quantified thing, the quantifier
285        is automatically "possessified".
286    
287    24. A recursive reference to a subpattern whose number was greater than 39
288        went wrong under certain circumstances in UTF-8 mode. This bug could also
289        have affected the operation of pcre_study().
290    
291    25. Realized that a little bit of performance could be had by replacing
292        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
293    
294    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
295    
296    27. Possessive quantifiers such as a++ were previously implemented by turning
297        them into atomic groups such as ($>a+). Now they have their own opcodes,
298        which improves performance. This includes the automatically created ones
299        from 23 above.
300    
301    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
302        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
303        the first matched character to be a colon. This applied both to named and
304        numbered groups.
305    
306    29. The ucpinternal.h header file was missing its idempotency #ifdef.
307    
308    30. I was sent a "project" file called libpcre.a.dev which I understand makes
309        building PCRE on Windows easier, so I have included it in the distribution.
310    
311    31. There is now a check in pcretest against a ridiculously large number being
312        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
313        loop, the loop is abandoned.
314    
315    32. Forward references to subpatterns in conditions such as (?(2)...) where
316        subpattern 2 is defined later cause pcre_compile() to search forwards in
317        the pattern for the relevant set of parentheses. This search went wrong
318        when there were unescaped parentheses in a character class, parentheses
319        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
320    
321    33. "Subroutine" calls and backreferences were previously restricted to
322        referencing subpatterns earlier in the regex. This restriction has now
323        been removed.
324    
325    34. Added a number of extra features that are going to be in Perl 5.10. On the
326        whole, these are just syntactic alternatives for features that PCRE had
327        previously implemented using the Python syntax or my own invention. The
328        other formats are all retained for compatibility.
329    
330        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
331            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
332            also .NET compatible.
333    
334        (b) A recursion or subroutine call to a named group can now be defined as
335            (?&name) as well as (?P>name).
336    
337        (c) A backreference to a named group can now be defined as \k<name> or
338            \k'name' as well as (?P=name). The new forms, as well as being in Perl
339            5.10, are also .NET compatible.
340    
341        (d) A conditional reference to a named group can now use the syntax
342            (?(<name>) or (?('name') as well as (?(name).
343    
344        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
345            groups (named and numbered) that are never evaluated inline, but can be
346            called as "subroutines" from elsewhere. In effect, the DEFINE condition
347            is always false. There may be only one alternative in such a group.
348    
349        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
350            as the simple (?(R). The condition is true only if the most recent
351            recursion is that of the given number or name. It does not search out
352            through the entire recursion stack.
353    
354        (g) The escape \gN or \g{N} has been added, where N is a positive or
355            negative number, specifying an absolute or relative reference.
356    
357    35. Tidied to get rid of some further signed/unsigned compiler warnings and
358        some "unreachable code" warnings.
359    
360    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
361        things, this adds five new scripts.
362    
363    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
364        There were also incompatibilities regarding the handling of \Q..\E inside
365        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
366        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
367    
368    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
369        matches an empty string, and forcibly breaks the loop. There were bugs in
370        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
371        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
372        separate and independent bugs (that affected different cases) have been
373        fixed.
374    
375    39. Refactored the code to abolish the use of different opcodes for small
376        capturing bracket numbers. This is a tidy that I avoided doing when I
377        removed the limit on the number of capturing brackets for 3.5 back in 2001.
378        The new approach is not only tidier, it makes it possible to reduce the
379        memory needed to fix the previous bug (38).
380    
381    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
382        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
383        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
384        mode.
385    
386    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
387        report.
388    
389    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
390        copy construction and assignment in the C++ wrapper.
391    
392    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
393        couple of bugs that could have given wrong results in the "--newline=crlf"
394        case.
395    
396    44. Added a number of casts and did some reorganization of signed/unsigned int
397        variables following suggestions from Dair Grant. Also renamed the variable
398        "this" as "item" because it is a C++ keyword.
399    
400    45. Arranged for dftables to add
401    
402          #include "pcre_internal.h"
403    
404        to pcre_chartables.c because without it, gcc 4.x may remove the array
405        definition from the final binary if PCRE is built into a static library and
406        dead code stripping is activated.
407    
408    46. For an unanchored pattern, if a match attempt fails at the start of a
409        newline sequence, and the newline setting is CRLF or ANY, and the next two
410        characters are CRLF, advance by two characters instead of one.
411    
412    
413    Version 6.7 04-Jul-06
414    ---------------------
415    
416     1. In order to handle tests when input lines are enormously long, pcretest has
417        been re-factored so that it automatically extends its buffers when
418        necessary. The code is crude, but this _is_ just a test program. The
419        default size has been increased from 32K to 50K.
420    
421     2. The code in pcre_study() was using the value of the re argument before
422        testing it for NULL. (Of course, in any sensible call of the function, it
423        won't be NULL.)
424    
425     3. The memmove() emulation function in pcre_internal.h, which is used on
426        systems that lack both memmove() and bcopy() - that is, hardly ever -
427        was missing a "static" storage class specifier.
428    
429     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
430        containing an extended class (one that cannot be represented by a bitmap
431        because it contains high-valued characters or Unicode property items, e.g.
432        [\pZ]). Almost always one would set UTF-8 mode when processing such a
433        pattern, but PCRE should not loop if you do not (it no longer does).
434        [Detail: two cases were found: (a) a repeated subpattern containing an
435        extended class; (b) a recursive reference to a subpattern that followed a
436        previous extended class. It wasn't skipping over the extended class
437        correctly when UTF-8 mode was not set.]
438    
439     5. A negated single-character class was not being recognized as fixed-length
440        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
441        compile error "lookbehind assertion is not fixed length".
442    
443     6. The RunPerlTest auxiliary script was showing an unexpected difference
444        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
445        write a Perl script that can interpret lines of an input file either as
446        byte characters or as UTF-8, which is what "perltest" was being required to
447        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
448        can't do is switch easily at run time between having the "use utf8;" pragma
449        or not. In the end, I fudged it by using the RunPerlTest script to insert
450        "use utf8;" explicitly for the UTF-8 tests.
451    
452     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
453        the end of the subject string, contrary to the documentation and to what
454        Perl does. This was true of both matching functions. Now it matches only at
455        the start of the subject and immediately after *internal* newlines.
456    
457     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
458        a pointer to an int instead of a pointer to an unsigned long int. This
459        caused problems on 64-bit systems.
460    
461     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
462        instance of the 'standard' template library not being so standard".
463    
464    10. There was no check on the number of named subpatterns nor the maximum
465        length of a subpattern name. The product of these values is used to compute
466        the size of the memory block for a compiled pattern. By supplying a very
467        long subpattern name and a large number of named subpatterns, the size
468        computation could be caused to overflow. This is now prevented by limiting
469        the length of names to 32 characters, and the number of named subpatterns
470        to 10,000.
471    
472    11. Subpatterns that are repeated with specific counts have to be replicated in
473        the compiled pattern. The size of memory for this was computed from the
474        length of the subpattern and the repeat count. The latter is limited to
475        65535, but there was no limit on the former, meaning that integer overflow
476        could in principle occur. The compiled length of a repeated subpattern is
477        now limited to 30,000 bytes in order to prevent this.
478    
479    12. Added the optional facility to have named substrings with the same name.
480    
481    13. Added the ability to use a named substring as a condition, using the
482        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
483        are numbers (not recommended). Forward references are permitted.
484    
485    14. Added forward references in named backreferences (if you see what I mean).
486    
487    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
488        pattern could run off the end of the subject. For example, the pattern
489        "(?s)(.{1,5})"8 did this with the subject "ab".
490    
491    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
492        PCRE_CASELESS was set when matching characters that were quantified with ?
493        or *.
494    
495    17. A character class other than a single negated character that had a minimum
496        but no maximum quantifier - for example [ab]{6,} - was not handled
497        correctly by pce_dfa_exec(). It would match only one character.
498    
499    18. A valid (though odd) pattern that looked like a POSIX character
500        class but used an invalid character after [ (for example [[,abc,]]) caused
501        pcre_compile() to give the error "Failed: internal error: code overflow" or
502        in some cases to crash with a glibc free() error. This could even happen if
503        the pattern terminated after [[ but there just happened to be a sequence of
504        letters, a binary zero, and a closing ] in the memory that followed.
505    
506    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
507        over the years. Originally (before any Unicode support), just the bottom 8
508        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
509        output from "man perlunicode" includes this:
510    
511          The regular expression compiler produces polymorphic opcodes.  That
512          is, the pattern adapts to the data and automatically switches to
513          the Unicode character scheme when presented with Unicode data--or
514          instead uses a traditional byte scheme when presented with byte
515          data.
516    
517        Sadly, a wide octal escape does not cause a switch, and in a string with
518        no other multibyte characters, these octal escapes are treated as before.
519        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
520        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
521        Unicode string.
522    
523        I have not perpetrated such confusion in PCRE. Up till now, it took just
524        the bottom 8 bits, as in old Perl. I have now made octal escapes with
525        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
526        translate to the appropriate multibyte character.
527    
528    29. Applied some refactoring to reduce the number of warnings from Microsoft
529        and Borland compilers. This has included removing the fudge introduced
530        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
531        a warning about an unused variable.
532    
533    21. PCRE has not included VT (character 0x0b) in the set of whitespace
534        characters since release 4.0, because Perl (from release 5.004) does not.
535        [Or at least, is documented not to: some releases seem to be in conflict
536        with the documentation.] However, when a pattern was studied with
537        pcre_study() and all its branches started with \s, PCRE still included VT
538        as a possible starting character. Of course, this did no harm; it just
539        caused an unnecessary match attempt.
540    
541    22. Removed a now-redundant internal flag bit that recorded the fact that case
542        dependency changed within the pattern. This was once needed for "required
543        byte" processing, but is no longer used. This recovers a now-scarce options
544        bit. Also moved the least significant internal flag bit to the most-
545        significant bit of the word, which was not previously used (hangover from
546        the days when it was an int rather than a uint) to free up another bit for
547        the future.
548    
549    23. Added support for CRLF line endings as well as CR and LF. As well as the
550        default being selectable at build time, it can now be changed at runtime
551        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
552        specify that it is scanning data with non-default line endings.
553    
554    24. Changed the definition of CXXLINK to make it agree with the definition of
555        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
556    
557    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
558        recursions. This makes a big different to stack usage for some patterns.
559    
560    26. If a subpattern containing a named recursion or subroutine reference such
561        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
562        the space required for the compiled pattern went wrong and gave too small a
563        value. Depending on the environment, this could lead to "Failed: internal
564        error: code overflow at offset 49" or "glibc detected double free or
565        corruption" errors.
566    
567    27. Applied patches from Google (a) to support the new newline modes and (b) to
568        advance over multibyte UTF-8 characters in GlobalReplace.
569    
570    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
571        difference for some implementation of PCRE in some Windows version.
572    
573    29. Added some extra testing facilities to pcretest:
574    
575        \q<number>   in a data line sets the "match limit" value
576        \Q<number>   in a data line sets the "match recursion limt" value
577        -S <number>  sets the stack size, where <number> is in megabytes
578    
579        The -S option isn't available for Windows.
580    
581    
582  Version 6.6 06-Feb-06  Version 6.6 06-Feb-06
583  ---------------------  ---------------------
584    

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