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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 01-May-07
5    ---------------------
7     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
8        which is apparently normally available under Windows.
10     2. Re-jig the pcregrep tests with different newline settings in an attempt
11        to make them independent of the local environment's newline setting.
13     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
15     4. Some of the "internals" tests were previously cut out when the link size
16        was not 2, because the output contained actual offsets. The recent new
17        "Z" feature of pcretest means that these can be cut out, making the tests
18        usable with all link sizes.
20     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
21        stack recursion. This gives a massive performance boost under BSD, but just
22        a small improvement under Linux. However, it saves one field in the frame
23        in all cases.
26    Version 7.1 24-Apr-07
27    ---------------------
29     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
30        that is more "standard", making use of automake and other Autotools. There
31        is some re-arrangement of the files and adjustment of comments consequent
32        on this.
34     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
35        for recursive directory scanning broke on some systems because the files
36        are not scanned in any specific order and on different systems the order
37        was different. A call to "sort" has been inserted into RunGrepTest for the
38        approprate test as a short-term fix. In the longer term there may be an
39        alternative.
41     3. I had an email from Eric Raymond about problems translating some of PCRE's
42        man pages to HTML (despite the fact that I distribute HTML pages, some
43        people do their own conversions for various reasons). The problems
44        concerned the use of low-level troff macros .br and .in. I have therefore
45        removed all such uses from the man pages (some were redundant, some could
46        be replaced by .nf/.fi pairs). The 132html script that I use to generate
47        HTML has been updated to handle .nf/.fi and to complain if it encounters
48        .br or .in.
50     4. Updated comments in configure.ac that get placed in config.h.in and also
51        arranged for config.h to be included in the distribution, with the name
52        config.h.generic, for the benefit of those who have to compile without
53        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
55     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
56        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
57        makevp.bat for the current PCRE, using the additional files
58        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
60     6. A Windows user reported a minor discrepancy with test 2, which turned out
61        to be caused by a trailing space on an input line that had got lost in his
62        copy. The trailing space was an accident, so I've just removed it.
64     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
65        that is needed.
67     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
68        as "const" (a) because they are and (b) because it helps the PHP
69        maintainers who have recently made a script to detect big data structures
70        in the php code that should be moved to the .rodata section. I remembered
71        to update Builducptable as well, so it won't revert if ucptable.h is ever
72        re-created.
74     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
75        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
76        order to be able to cut out the UTF-8 tables in the latter when UTF-8
77        support is not required. This saves 1.5-2K of code, which is important in
78        some applications.
80        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
81        so as not to refer to the tables, even though these functions will never be
82        called when UTF-8 support is disabled. Otherwise there are problems with a
83        shared library.
85    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
87        (a) It was defining its arguments as char * instead of void *.
89        (b) It was assuming that all moves were upwards in memory; this was true
90            a long time ago when I wrote it, but is no longer the case.
92        The emulated memove() is provided for those environments that have neither
93        memmove() nor bcopy(). I didn't think anyone used it these days, but that
94        is clearly not the case, as these two bugs were recently reported.
96    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
97        and Detrail to create the HTML documentation, the .txt form of the man
98        pages, and it removes trailing spaces from listed files. It also creates
99        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
100        case, it wraps all the #defines with #ifndefs. This script should be run
101        before "make dist".
103    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
104        with Unicode property support.
106        (a) For a maximizing quantifier, if the two different cases of the
107            character were of different lengths in their UTF-8 codings (there are
108            some cases like this - I found 11), and the matching function had to
109            back up over a mixture of the two cases, it incorrectly assumed they
110            were both the same length.
112        (b) When PCRE was configured to use the heap rather than the stack for
113            recursion during matching, it was not correctly preserving the data for
114            the other case of a UTF-8 character when checking ahead for a match
115            while processing a minimizing repeat. If the check also involved
116            matching a wide character, but failed, corruption could cause an
117            erroneous result when trying to check for a repeat of the original
118            character.
120    13. Some tidying changes to the testing mechanism:
122        (a) The RunTest script now detects the internal link size and whether there
123            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
124            values substituted by "configure". (The RunGrepTest script already did
125            this for UTF-8.) The configure.ac script no longer substitutes the
126            relevant variables.
128        (b) The debugging options /B and /D in pcretest show the compiled bytecode
129            with length and offset values. This means that the output is different
130            for different internal link sizes. Test 2 is skipped for link sizes
131            other than 2 because of this, bypassing the problem. Unfortunately,
132            there was also a test in test 3 (the locale tests) that used /B and
133            failed for link sizes other than 2. Rather than cut the whole test out,
134            I have added a new /Z option to pcretest that replaces the length and
135            offset values with spaces. This is now used to make test 3 independent
136            of link size. (Test 2 will be tidied up later.)
138    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
139        segmentation fault instead of returning the appropriate error message.
141    15. In multiline mode when the newline sequence was set to "any", the pattern
142        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
143        This doesn't seem right; it now treats the CRLF combination as the line
144        ending, and so does not match in that case. It's only a pattern such as ^$
145        that would hit this one: something like ^ABC$ would have failed after \r
146        and then tried again after \r\n.
148    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
149        in an attempt to make files that differ only in their line terminators
150        compare equal. This works on Linux.
152    17. Under certain error circumstances pcregrep might try to free random memory
153        as it exited. This is now fixed, thanks to valgrind.
155    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
156        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
157        was because its rules for how to advance for /g after matching an empty
158        string at the end of a line did not allow for this case. They now check for
159        it specially.
161    20. pcretest is supposed to handle patterns and data of any length, by
162        extending its buffers when necessary. It was getting this wrong when the
163        buffer for a data line had to be extended.
165    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
166        CRLF as a newline sequence.
168    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
169        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
170        I have nevertheless tidied it up.
172    23. Added some casts to kill warnings from HP-UX ia64 compiler.
174    24. Added a man page for pcre-config.
177    Version 7.0 19-Dec-06
178    ---------------------
180     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
181        moving to gcc 4.1.1.
183     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
184        sys/time.h, which is documented as needed for this function. It doesn't
185        seem to matter on Linux, but it showed up on some releases of OS X.
187     3. It seems that there are systems where bytes whose values are greater than
188        127 match isprint() in the "C" locale. The "C" locale should be the
189        default when a C program starts up. In most systems, only ASCII printing
190        characters match isprint(). This difference caused the output from pcretest
191        to vary, making some of the tests fail. I have changed pcretest so that:
193        (a) When it is outputting text in the compiled version of a pattern, bytes
194            other than 32-126 are always shown as hex escapes.
196        (b) When it is outputting text that is a matched part of a subject string,
197            it does the same, unless a different locale has been set for the match
198            (using the /L modifier). In this case, it uses isprint() to decide.
200     4. Fixed a major bug that caused incorrect computation of the amount of memory
201        required for a compiled pattern when options that changed within the
202        pattern affected the logic of the preliminary scan that determines the
203        length. The relevant options are -x, and -i in UTF-8 mode. The result was
204        that the computed length was too small. The symptoms of this bug were
205        either the PCRE error "internal error: code overflow" from pcre_compile(),
206        or a glibc crash with a message such as "pcretest: free(): invalid next
207        size (fast)". Examples of patterns that provoked this bug (shown in
208        pcretest format) are:
210          /(?-x: )/x
211          /(?x)(?-x: \s*#\s*)/
212          /((?i)[\x{c0}])/8
213          /(?i:[\x{c0}])/8
215        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
216        is now done differently.
218     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
219        wrapper classes; (b) implement a new function in the C++ scanner that is
220        more efficient than the old way of doing things because it avoids levels of
221        recursion in the regex matching; (c) add a paragraph to the documentation
222        for the FullMatch() function.
224     6. The escape sequence \n was being treated as whatever was defined as
225        "newline". Not only was this contrary to the documentation, which states
226        that \n is character 10 (hex 0A), but it also went horribly wrong when
227        "newline" was defined as CRLF. This has been fixed.
229     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
230        was being set to -1 for the "end of line" case (supposedly a value that no
231        character can have). Though this value is never used (the check for end of
232        line is "zero bytes in current character"), it caused compiler complaints.
233        I've changed it to 0xffffffff.
235     8. In pcre_version.c, the version string was being built by a sequence of
236        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
237        string (as it is for production releases) called a macro with an empty
238        argument. The C standard says the result of this is undefined. The gcc
239        compiler treats it as an empty string (which was what was wanted) but it is
240        reported that Visual C gives an error. The source has been hacked around to
241        avoid this problem.
243     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
244        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
245        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
246        of them did).
248    10. Originally, pcretest opened its input and output without "b"; then I was
249        told that "b" was needed in some environments, so it was added for release
250        5.0 to both the input and output. (It makes no difference on Unix-like
251        systems.) Later I was told that it is wrong for the input on Windows. I've
252        now abstracted the modes into two macros, to make it easier to fiddle with
253        them, and removed "b" from the input mode under Windows.
255    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
257    12. Added -help and --help to pcretest as an official way of being reminded
258        of the options.
260    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
261        and pcrecpp.cc because they annoy compilers at high warning levels.
263    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
265    15. Fixed an occurrence of == in configure.ac that should have been = (shell
266        scripts are not C programs :-) and which was not noticed because it works
267        on Linux.
269    16. pcretest is supposed to handle any length of pattern and data line (as one
270        line or as a continued sequence of lines) by extending its input buffer if
271        necessary. This feature was broken for very long pattern lines, leading to
272        a string of junk being passed to pcre_compile() if the pattern was longer
273        than about 50K.
275    17. I have done a major re-factoring of the way pcre_compile() computes the
276        amount of memory needed for a compiled pattern. Previously, there was code
277        that made a preliminary scan of the pattern in order to do this. That was
278        OK when PCRE was new, but as the facilities have expanded, it has become
279        harder and harder to keep it in step with the real compile phase, and there
280        have been a number of bugs (see for example, 4 above). I have now found a
281        cunning way of running the real compile function in a "fake" mode that
282        enables it to compute how much memory it would need, while actually only
283        ever using a few hundred bytes of working memory and without too many
284        tests of the mode. This should make future maintenance and development
285        easier. A side effect of this work is that the limit of 200 on the nesting
286        depth of parentheses has been removed (though this was never a serious
287        limitation, I suspect). However, there is a downside: pcre_compile() now
288        runs more slowly than before (30% or more, depending on the pattern). I
289        hope this isn't a big issue. There is no effect on runtime performance.
291    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
292        newline (only possible for the last line of a file) and it was a
293        pattern that set a locale (followed by /Lsomething), pcretest crashed.
295    19. Added additional timing features to pcretest. (1) The -tm option now times
296        matching only, not compiling. (2) Both -t and -tm can be followed, as a
297        separate command line item, by a number that specifies the number of
298        repeats to use when timing. The default is 50000; this gives better
299        precision, but takes uncomfortably long for very large patterns.
301    20. Extended pcre_study() to be more clever in cases where a branch of a
302        subpattern has no definite first character. For example, (a*|b*)[cd] would
303        previously give no result from pcre_study(). Now it recognizes that the
304        first character must be a, b, c, or d.
306    21. There was an incorrect error "recursive call could loop indefinitely" if
307        a subpattern (or the entire pattern) that was being tested for matching an
308        empty string contained only one non-empty item after a nested subpattern.
309        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
310        incorrectly, because the \d was being skipped in the check.
312    22. The pcretest program now has a new pattern option /B and a command line
313        option -b, which is equivalent to adding /B to every pattern. This causes
314        it to show the compiled bytecode, without the additional information that
315        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
316        is the same as /B/I).
318    23. A new optimization is now able automatically to treat some sequences such
319        as a*b as a*+b. More specifically, if something simple (such as a character
320        or a simple class like \d) has an unlimited quantifier, and is followed by
321        something that cannot possibly match the quantified thing, the quantifier
322        is automatically "possessified".
324    24. A recursive reference to a subpattern whose number was greater than 39
325        went wrong under certain circumstances in UTF-8 mode. This bug could also
326        have affected the operation of pcre_study().
328    25. Realized that a little bit of performance could be had by replacing
329        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
331    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
333    27. Possessive quantifiers such as a++ were previously implemented by turning
334        them into atomic groups such as ($>a+). Now they have their own opcodes,
335        which improves performance. This includes the automatically created ones
336        from 23 above.
338    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
339        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
340        the first matched character to be a colon. This applied both to named and
341        numbered groups.
343    29. The ucpinternal.h header file was missing its idempotency #ifdef.
345    30. I was sent a "project" file called libpcre.a.dev which I understand makes
346        building PCRE on Windows easier, so I have included it in the distribution.
348    31. There is now a check in pcretest against a ridiculously large number being
349        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
350        loop, the loop is abandoned.
352    32. Forward references to subpatterns in conditions such as (?(2)...) where
353        subpattern 2 is defined later cause pcre_compile() to search forwards in
354        the pattern for the relevant set of parentheses. This search went wrong
355        when there were unescaped parentheses in a character class, parentheses
356        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
358    33. "Subroutine" calls and backreferences were previously restricted to
359        referencing subpatterns earlier in the regex. This restriction has now
360        been removed.
362    34. Added a number of extra features that are going to be in Perl 5.10. On the
363        whole, these are just syntactic alternatives for features that PCRE had
364        previously implemented using the Python syntax or my own invention. The
365        other formats are all retained for compatibility.
367        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
368            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
369            also .NET compatible.
371        (b) A recursion or subroutine call to a named group can now be defined as
372            (?&name) as well as (?P>name).
374        (c) A backreference to a named group can now be defined as \k<name> or
375            \k'name' as well as (?P=name). The new forms, as well as being in Perl
376            5.10, are also .NET compatible.
378        (d) A conditional reference to a named group can now use the syntax
379            (?(<name>) or (?('name') as well as (?(name).
381        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
382            groups (named and numbered) that are never evaluated inline, but can be
383            called as "subroutines" from elsewhere. In effect, the DEFINE condition
384            is always false. There may be only one alternative in such a group.
386        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
387            as the simple (?(R). The condition is true only if the most recent
388            recursion is that of the given number or name. It does not search out
389            through the entire recursion stack.
391        (g) The escape \gN or \g{N} has been added, where N is a positive or
392            negative number, specifying an absolute or relative reference.
394    35. Tidied to get rid of some further signed/unsigned compiler warnings and
395        some "unreachable code" warnings.
397    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
398        things, this adds five new scripts.
400    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
401        There were also incompatibilities regarding the handling of \Q..\E inside
402        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
403        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
405    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
406        matches an empty string, and forcibly breaks the loop. There were bugs in
407        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
408        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
409        separate and independent bugs (that affected different cases) have been
410        fixed.
412    39. Refactored the code to abolish the use of different opcodes for small
413        capturing bracket numbers. This is a tidy that I avoided doing when I
414        removed the limit on the number of capturing brackets for 3.5 back in 2001.
415        The new approach is not only tidier, it makes it possible to reduce the
416        memory needed to fix the previous bug (38).
418    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
419        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
420        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
421        mode.
423    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
424        report.
426    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
427        copy construction and assignment in the C++ wrapper.
429    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
430        couple of bugs that could have given wrong results in the "--newline=crlf"
431        case.
433    44. Added a number of casts and did some reorganization of signed/unsigned int
434        variables following suggestions from Dair Grant. Also renamed the variable
435        "this" as "item" because it is a C++ keyword.
437    45. Arranged for dftables to add
439          #include "pcre_internal.h"
441        to pcre_chartables.c because without it, gcc 4.x may remove the array
442        definition from the final binary if PCRE is built into a static library and
443        dead code stripping is activated.
445    46. For an unanchored pattern, if a match attempt fails at the start of a
446        newline sequence, and the newline setting is CRLF or ANY, and the next two
447        characters are CRLF, advance by two characters instead of one.
450    Version 6.7 04-Jul-06
451    ---------------------
453     1. In order to handle tests when input lines are enormously long, pcretest has
454        been re-factored so that it automatically extends its buffers when
455        necessary. The code is crude, but this _is_ just a test program. The
456        default size has been increased from 32K to 50K.
458     2. The code in pcre_study() was using the value of the re argument before
459        testing it for NULL. (Of course, in any sensible call of the function, it
460        won't be NULL.)
462     3. The memmove() emulation function in pcre_internal.h, which is used on
463        systems that lack both memmove() and bcopy() - that is, hardly ever -
464        was missing a "static" storage class specifier.
466     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
467        containing an extended class (one that cannot be represented by a bitmap
468        because it contains high-valued characters or Unicode property items, e.g.
469        [\pZ]). Almost always one would set UTF-8 mode when processing such a
470        pattern, but PCRE should not loop if you do not (it no longer does).
471        [Detail: two cases were found: (a) a repeated subpattern containing an
472        extended class; (b) a recursive reference to a subpattern that followed a
473        previous extended class. It wasn't skipping over the extended class
474        correctly when UTF-8 mode was not set.]
476     5. A negated single-character class was not being recognized as fixed-length
477        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
478        compile error "lookbehind assertion is not fixed length".
480     6. The RunPerlTest auxiliary script was showing an unexpected difference
481        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
482        write a Perl script that can interpret lines of an input file either as
483        byte characters or as UTF-8, which is what "perltest" was being required to
484        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
485        can't do is switch easily at run time between having the "use utf8;" pragma
486        or not. In the end, I fudged it by using the RunPerlTest script to insert
487        "use utf8;" explicitly for the UTF-8 tests.
489     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
490        the end of the subject string, contrary to the documentation and to what
491        Perl does. This was true of both matching functions. Now it matches only at
492        the start of the subject and immediately after *internal* newlines.
494     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
495        a pointer to an int instead of a pointer to an unsigned long int. This
496        caused problems on 64-bit systems.
498     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
499        instance of the 'standard' template library not being so standard".
501    10. There was no check on the number of named subpatterns nor the maximum
502        length of a subpattern name. The product of these values is used to compute
503        the size of the memory block for a compiled pattern. By supplying a very
504        long subpattern name and a large number of named subpatterns, the size
505        computation could be caused to overflow. This is now prevented by limiting
506        the length of names to 32 characters, and the number of named subpatterns
507        to 10,000.
509    11. Subpatterns that are repeated with specific counts have to be replicated in
510        the compiled pattern. The size of memory for this was computed from the
511        length of the subpattern and the repeat count. The latter is limited to
512        65535, but there was no limit on the former, meaning that integer overflow
513        could in principle occur. The compiled length of a repeated subpattern is
514        now limited to 30,000 bytes in order to prevent this.
516    12. Added the optional facility to have named substrings with the same name.
518    13. Added the ability to use a named substring as a condition, using the
519        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
520        are numbers (not recommended). Forward references are permitted.
522    14. Added forward references in named backreferences (if you see what I mean).
524    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
525        pattern could run off the end of the subject. For example, the pattern
526        "(?s)(.{1,5})"8 did this with the subject "ab".
528    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
529        PCRE_CASELESS was set when matching characters that were quantified with ?
530        or *.
532    17. A character class other than a single negated character that had a minimum
533        but no maximum quantifier - for example [ab]{6,} - was not handled
534        correctly by pce_dfa_exec(). It would match only one character.
536    18. A valid (though odd) pattern that looked like a POSIX character
537        class but used an invalid character after [ (for example [[,abc,]]) caused
538        pcre_compile() to give the error "Failed: internal error: code overflow" or
539        in some cases to crash with a glibc free() error. This could even happen if
540        the pattern terminated after [[ but there just happened to be a sequence of
541        letters, a binary zero, and a closing ] in the memory that followed.
543    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
544        over the years. Originally (before any Unicode support), just the bottom 8
545        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
546        output from "man perlunicode" includes this:
548          The regular expression compiler produces polymorphic opcodes.  That
549          is, the pattern adapts to the data and automatically switches to
550          the Unicode character scheme when presented with Unicode data--or
551          instead uses a traditional byte scheme when presented with byte
552          data.
554        Sadly, a wide octal escape does not cause a switch, and in a string with
555        no other multibyte characters, these octal escapes are treated as before.
556        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
557        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
558        Unicode string.
560        I have not perpetrated such confusion in PCRE. Up till now, it took just
561        the bottom 8 bits, as in old Perl. I have now made octal escapes with
562        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
563        translate to the appropriate multibyte character.
565    29. Applied some refactoring to reduce the number of warnings from Microsoft
566        and Borland compilers. This has included removing the fudge introduced
567        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
568        a warning about an unused variable.
570    21. PCRE has not included VT (character 0x0b) in the set of whitespace
571        characters since release 4.0, because Perl (from release 5.004) does not.
572        [Or at least, is documented not to: some releases seem to be in conflict
573        with the documentation.] However, when a pattern was studied with
574        pcre_study() and all its branches started with \s, PCRE still included VT
575        as a possible starting character. Of course, this did no harm; it just
576        caused an unnecessary match attempt.
578    22. Removed a now-redundant internal flag bit that recorded the fact that case
579        dependency changed within the pattern. This was once needed for "required
580        byte" processing, but is no longer used. This recovers a now-scarce options
581        bit. Also moved the least significant internal flag bit to the most-
582        significant bit of the word, which was not previously used (hangover from
583        the days when it was an int rather than a uint) to free up another bit for
584        the future.
586    23. Added support for CRLF line endings as well as CR and LF. As well as the
587        default being selectable at build time, it can now be changed at runtime
588        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
589        specify that it is scanning data with non-default line endings.
591    24. Changed the definition of CXXLINK to make it agree with the definition of
592        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
594    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
595        recursions. This makes a big different to stack usage for some patterns.
597    26. If a subpattern containing a named recursion or subroutine reference such
598        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
599        the space required for the compiled pattern went wrong and gave too small a
600        value. Depending on the environment, this could lead to "Failed: internal
601        error: code overflow at offset 49" or "glibc detected double free or
602        corruption" errors.
604    27. Applied patches from Google (a) to support the new newline modes and (b) to
605        advance over multibyte UTF-8 characters in GlobalReplace.
607    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
608        difference for some implementation of PCRE in some Windows version.
610    29. Added some extra testing facilities to pcretest:
612        \q<number>   in a data line sets the "match limit" value
613        \Q<number>   in a data line sets the "match recursion limt" value
614        -S <number>  sets the stack size, where <number> is in megabytes
616        The -S option isn't available for Windows.
619    Version 6.6 06-Feb-06
620    ---------------------
622     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
623        in pcreposix.h. I have copied the definition from pcre.h.
625     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
626        because pcre.h is no longer a built file.
628     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
629        not normally included in the compiled code.
632  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
633  ---------------------  ---------------------

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