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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.10 03-Jun-2010  Version 8.37 28-April-2015
5    --------------------------
7    1.  When an (*ACCEPT) is triggered inside capturing parentheses, it arranges
8        for those parentheses to be closed with whatever has been captured so far.
9        However, it was failing to mark any other groups between the hightest
10        capture so far and the currrent group as "unset". Thus, the ovector for
11        those groups contained whatever was previously there. An example is the
12        pattern /(x)|((*ACCEPT))/ when matched against "abcd".
14    2.  If an assertion condition was quantified with a minimum of zero (an odd
15        thing to do, but it happened), SIGSEGV or other misbehaviour could occur.
17    3.  If a pattern in pcretest input had the P (POSIX) modifier followed by an
18        unrecognized modifier, a crash could occur.
20    4.  An attempt to do global matching in pcretest with a zero-length ovector
21        caused a crash.
23    5.  Fixed a memory leak during matching that could occur for a subpattern
24        subroutine call (recursive or otherwise) if the number of captured groups
25        that had to be saved was greater than ten.
27    6.  Catch a bad opcode during auto-possessification after compiling a bad UTF
28        string with NO_UTF_CHECK. This is a tidyup, not a bug fix, as passing bad
29        UTF with NO_UTF_CHECK is documented as having an undefined outcome.
31    7.  A UTF pattern containing a "not" match of a non-ASCII character and a
32        subroutine reference could loop at compile time. Example: /[^\xff]((?1))/.
34    8. When a pattern is compiled, it remembers the highest back reference so that
35       when matching, if the ovector is too small, extra memory can be obtained to
36       use instead. A conditional subpattern whose condition is a check on a
37       capture having happened, such as, for example in the pattern
38       /^(?:(a)|b)(?(1)A|B)/, is another kind of back reference, but it was not
39       setting the highest backreference number. This mattered only if pcre_exec()
40       was called with an ovector that was too small to hold the capture, and there
41       was no other kind of back reference (a situation which is probably quite
42       rare). The effect of the bug was that the condition was always treated as
43       FALSE when the capture could not be consulted, leading to a incorrect
44       behaviour by pcre_exec(). This bug has been fixed.
46    9. A reference to a duplicated named group (either a back reference or a test
47       for being set in a conditional) that occurred in a part of the pattern where
48       PCRE_DUPNAMES was not set caused the amount of memory needed for the pattern
49       to be incorrectly calculated, leading to overwriting.
51    10. A mutually recursive set of back references such as (\2)(\1) caused a
52        segfault at study time (while trying to find the minimum matching length).
53        The infinite loop is now broken (with the minimum length unset, that is,
54        zero).
56    11. If an assertion that was used as a condition was quantified with a minimum
57        of zero, matching went wrong. In particular, if the whole group had
58        unlimited repetition and could match an empty string, a segfault was
59        likely. The pattern (?(?=0)?)+ is an example that caused this. Perl allows
60        assertions to be quantified, but not if they are being used as conditions,
61        so the above pattern is faulted by Perl. PCRE has now been changed so that
62        it also rejects such patterns.
64    12. A possessive capturing group such as (a)*+ with a minimum repeat of zero
65        failed to allow the zero-repeat case if pcre2_exec() was called with an
66        ovector too small to capture the group.
68    13. Fixed two bugs in pcretest that were discovered by fuzzing and reported by
69        Red Hat Product Security:
71        (a) A crash if /K and /F were both set with the option to save the compiled
72        pattern.
74        (b) Another crash if the option to print captured substrings in a callout
75        was combined with setting a null ovector, for example \O\C+ as a subject
76        string.
78    14. A pattern such as "((?2){0,1999}())?", which has a group containing a
79        forward reference repeated a large (but limited) number of times within a
80        repeated outer group that has a zero minimum quantifier, caused incorrect
81        code to be compiled, leading to the error "internal error:
82        previously-checked referenced subpattern not found" when an incorrect
83        memory address was read. This bug was reported as "heap overflow",
84        discovered by Kai Lu of Fortinet's FortiGuard Labs and given the CVE number
85        CVE-2015-2325.
87    23. A pattern such as "((?+1)(\1))/" containing a forward reference subroutine
88        call within a group that also contained a recursive back reference caused
89        incorrect code to be compiled. This bug was reported as "heap overflow",
90        discovered by Kai Lu of Fortinet's FortiGuard Labs, and given the CVE
91        number CVE-2015-2326.
93    24. Computing the size of the JIT read-only data in advance has been a source
94        of various issues, and new ones are still appear unfortunately. To fix
95        existing and future issues, size computation is eliminated from the code,
96        and replaced by on-demand memory allocation.
98    25. A pattern such as /(?i)[A-`]/, where characters in the other case are
99        adjacent to the end of the range, and the range contained characters with
100        more than one other case, caused incorrect behaviour when compiled in UTF
101        mode. In that example, the range a-j was left out of the class.
103    26. Fix JIT compilation of conditional blocks, which assertion
104        is converted to (*FAIL). E.g: /(?(?!))/.
106    27. The pattern /(?(?!)^)/ caused references to random memory. This bug was
107        discovered by the LLVM fuzzer.
109    28. The assertion (?!) is optimized to (*FAIL). This was not handled correctly
110        when this assertion was used as a condition, for example (?(?!)a|b). In
111        pcre2_match() it worked by luck; in pcre2_dfa_match() it gave an incorrect
112        error about an unsupported item.
114    29. For some types of pattern, for example /Z*(|d*){216}/, the auto-
115        possessification code could take exponential time to complete. A recursion
116        depth limit of 1000 has been imposed to limit the resources used by this
117        optimization.
119    30. A pattern such as /(*UTF)[\S\V\H]/, which contains a negated special class
120        such as \S in non-UCP mode, explicit wide characters (> 255) can be ignored
121        because \S ensures they are all in the class. The code for doing this was
122        interacting badly with the code for computing the amount of space needed to
123        compile the pattern, leading to a buffer overflow. This bug was discovered
124        by the LLVM fuzzer.
126    31. A pattern such as /((?2)+)((?1))/ which has mutual recursion nested inside
127        other kinds of group caused stack overflow at compile time. This bug was
128        discovered by the LLVM fuzzer.
130    32. A pattern such as /(?1)(?#?'){8}(a)/ which had a parenthesized comment
131        between a subroutine call and its quantifier was incorrectly compiled,
132        leading to buffer overflow or other errors. This bug was discovered by the
133        LLVM fuzzer.
135    33. The illegal pattern /(?(?<E>.*!.*)?)/ was not being diagnosed as missing an
136        assertion after (?(. The code was failing to check the character after
137        (?(?< for the ! or = that would indicate a lookbehind assertion. This bug
138        was discovered by the LLVM fuzzer.
140    34. A pattern such as /X((?2)()*+){2}+/ which has a possessive quantifier with
141        a fixed maximum following a group that contains a subroutine reference was
142        incorrectly compiled and could trigger buffer overflow. This bug was
143        discovered by the LLVM fuzzer.
145    35. A mutual recursion within a lookbehind assertion such as (?<=((?2))((?1)))
146        caused a stack overflow instead of the diagnosis of a non-fixed length
147        lookbehind assertion. This bug was discovered by the LLVM fuzzer.
149    36. The use of \K in a positive lookbehind assertion in a non-anchored pattern
150        (e.g. /(?<=\Ka)/) could make pcregrep loop.
152    37. There was a similar problem to 36 in pcretest for global matches.
154    38. If a greedy quantified \X was preceded by \C in UTF mode (e.g. \C\X*),
155        and a subsequent item in the pattern caused a non-match, backtracking over
156        the repeated \X did not stop, but carried on past the start of the subject,
157        causing reference to random memory and/or a segfault. There were also some
158        other cases where backtracking after \C could crash. This set of bugs was
159        discovered by the LLVM fuzzer.
161    39. The function for finding the minimum length of a matching string could take
162        a very long time if mutual recursion was present many times in a pattern,
163        for example, /((?2){73}(?2))((?1))/. A better mutual recursion detection
164        method has been implemented. This infelicity was discovered by the LLVM
165        fuzzer.
167    40. Static linking against the PCRE library using the pkg-config module was
168        failing on missing pthread symbols.
171    Version 8.36 26-September-2014
172    ------------------------------
174    1.  Got rid of some compiler warnings in the C++ modules that were shown up by
175        -Wmissing-field-initializers and -Wunused-parameter.
177    2.  The tests for quantifiers being too big (greater than 65535) were being
178        applied after reading the number, and stupidly assuming that integer
179        overflow would give a negative number. The tests are now applied as the
180        numbers are read.
182    3.  Tidy code in pcre_exec.c where two branches that used to be different are
183        now the same.
185    4.  The JIT compiler did not generate match limit checks for certain
186        bracketed expressions with quantifiers. This may lead to exponential
187        backtracking, instead of returning with PCRE_ERROR_MATCHLIMIT. This
188        issue should be resolved now.
190    5.  Fixed an issue, which occures when nested alternatives are optimized
191        with table jumps.
193    6.  Inserted two casts and changed some ints to size_t in the light of some
194        reported 64-bit compiler warnings (Bugzilla 1477).
196    7.  Fixed a bug concerned with zero-minimum possessive groups that could match
197        an empty string, which sometimes were behaving incorrectly in the
198        interpreter (though correctly in the JIT matcher). This pcretest input is
199        an example:
201          '\A(?:[^"]++|"(?:[^"]*+|"")*+")++'
204        the interpreter was reporting a match of 'NON QUOTED ' only, whereas the
205        JIT matcher and Perl both matched 'NON QUOTED "QUOT""ED" AFTER '. The test
206        for an empty string was breaking the inner loop and carrying on at a lower
207        level, when possessive repeated groups should always return to a higher
208        level as they have no backtrack points in them. The empty string test now
209        occurs at the outer level.
211    8.  Fixed a bug that was incorrectly auto-possessifying \w+ in the pattern
212        ^\w+(?>\s*)(?<=\w) which caused it not to match "test test".
214    9.  Give a compile-time error for \o{} (as Perl does) and for \x{} (which Perl
215        doesn't).
217    10. Change 8.34/15 introduced a bug that caused the amount of memory needed
218        to hold a pattern to be incorrectly computed (too small) when there were
219        named back references to duplicated names. This could cause "internal
220        error: code overflow" or "double free or corruption" or other memory
221        handling errors.
223    11. When named subpatterns had the same prefixes, back references could be
224        confused. For example, in this pattern:
226          /(?P<Name>a)?(?P<Name2>b)?(?(<Name>)c|d)*l/
228        the reference to 'Name' was incorrectly treated as a reference to a
229        duplicate name.
231    12. A pattern such as /^s?c/mi8 where the optional character has more than
232        one "other case" was incorrectly compiled such that it would only try to
233        match starting at "c".
235    13. When a pattern starting with \s was studied, VT was not included in the
236        list of possible starting characters; this should have been part of the
237        8.34/18 patch.
239    14. If a character class started [\Qx]... where x is any character, the class
240        was incorrectly terminated at the ].
242    15. If a pattern that started with a caseless match for a character with more
243        than one "other case" was studied, PCRE did not set up the starting code
244        unit bit map for the list of possible characters. Now it does. This is an
245        optimization improvement, not a bug fix.
247    16. The Unicode data tables have been updated to Unicode 7.0.0.
249    17. Fixed a number of memory leaks in pcregrep.
251    18. Avoid a compiler warning (from some compilers) for a function call with
252        a cast that removes "const" from an lvalue by using an intermediate
253        variable (to which the compiler does not object).
255    19. Incorrect code was compiled if a group that contained an internal recursive
256        back reference was optional (had quantifier with a minimum of zero). This
257        example compiled incorrect code: /(((a\2)|(a*)\g<-1>))*/ and other examples
258        caused segmentation faults because of stack overflows at compile time.
260    20. A pattern such as /((?(R)a|(?1)))+/, which contains a recursion within a
261        group that is quantified with an indefinite repeat, caused a compile-time
262        loop which used up all the system stack and provoked a segmentation fault.
263        This was not the same bug as 19 above.
265    21. Add PCRECPP_EXP_DECL declaration to operator<< in pcre_stringpiece.h.
266        Patch by Mike Frysinger.
269    Version 8.35 04-April-2014
270    --------------------------
272    1.  A new flag is set, when property checks are present in an XCLASS.
273        When this flag is not set, PCRE can perform certain optimizations
274        such as studying these XCLASS-es.
276    2.  The auto-possessification of character sets were improved: a normal
277        and an extended character set can be compared now. Furthermore
278        the JIT compiler optimizes more character set checks.
280    3.  Got rid of some compiler warnings for potentially uninitialized variables
281        that show up only when compiled with -O2.
283    4.  A pattern such as (?=ab\K) that uses \K in an assertion can set the start
284        of a match later then the end of the match. The pcretest program was not
285        handling the case sensibly - it was outputting from the start to the next
286        binary zero. It now reports this situation in a message, and outputs the
287        text from the end to the start.
289    5.  Fast forward search is improved in JIT. Instead of the first three
290        characters, any three characters with fixed position can be searched.
291        Search order: first, last, middle.
293    6.  Improve character range checks in JIT. Characters are read by an inprecise
294        function now, which returns with an unknown value if the character code is
295        above a certain threshold (e.g: 256). The only limitation is that the value
296        must be bigger than the threshold as well. This function is useful when
297        the characters above the threshold are handled in the same way.
299    7.  The macros whose names start with RAWUCHAR are placeholders for a future
300        mode in which only the bottom 21 bits of 32-bit data items are used. To
301        make this more memorable for those maintaining the code, the names have
302        been changed to start with UCHAR21, and an extensive comment has been added
303        to their definition.
305    8.  Add missing (new) files sljitNativeTILEGX.c and sljitNativeTILEGX-encoder.c
306        to the export list in Makefile.am (they were accidentally omitted from the
307        8.34 tarball).
309    9.  The informational output from pcretest used the phrase "starting byte set"
310        which is inappropriate for the 16-bit and 32-bit libraries. As the output
311        for "first char" and "need char" really means "non-UTF-char", I've changed
312        "byte" to "char", and slightly reworded the output. The documentation about
313        these values has also been (I hope) clarified.
315    10. Another JIT related optimization: use table jumps for selecting the correct
316        backtracking path, when more than four alternatives are present inside a
317        bracket.
319    11. Empty match is not possible, when the minimum length is greater than zero,
320        and there is no \K in the pattern. JIT should avoid empty match checks in
321        such cases.
323    12. In a caseless character class with UCP support, when a character with more
324        than one alternative case was not the first character of a range, not all
325        the alternative cases were added to the class. For example, s and \x{17f}
326        are both alternative cases for S: the class [RST] was handled correctly,
327        but [R-T] was not.
329    13. The configure.ac file always checked for pthread support when JIT was
330        enabled. This is not used in Windows, so I have put this test inside a
331        check for the presence of windows.h (which was already tested for).
333    14. Improve pattern prefix search by a simplified Boyer-Moore algorithm in JIT.
334        The algorithm provides a way to skip certain starting offsets, and usually
335        faster than linear prefix searches.
337    15. Change 13 for 8.20 updated RunTest to check for the 'fr' locale as well
338        as for 'fr_FR' and 'french'. For some reason, however, it then used the
339        Windows-specific input and output files, which have 'french' screwed in.
340        So this could never have worked. One of the problems with locales is that
341        they aren't always the same. I have now updated RunTest so that it checks
342        the output of the locale test (test 3) against three different output
343        files, and it allows the test to pass if any one of them matches. With luck
344        this should make the test pass on some versions of Solaris where it was
345        failing. Because of the uncertainty, the script did not used to stop if
346        test 3 failed; it now does. If further versions of a French locale ever
347        come to light, they can now easily be added.
349    16. If --with-pcregrep-bufsize was given a non-integer value such as "50K",
350        there was a message during ./configure, but it did not stop. This now
351        provokes an error. The invalid example in README has been corrected.
352        If a value less than the minimum is given, the minimum value has always
353        been used, but now a warning is given.
355    17. If --enable-bsr-anycrlf was set, the special 16/32-bit test failed. This
356        was a bug in the test system, which is now fixed. Also, the list of various
357        configurations that are tested for each release did not have one with both
358        16/32 bits and --enable-bar-anycrlf. It now does.
360    18. pcretest was missing "-C bsr" for displaying the \R default setting.
362    19. Little endian PowerPC systems are supported now by the JIT compiler.
364    20. The fast forward newline mechanism could enter to an infinite loop on
365        certain invalid UTF-8 input. Although we don't support these cases
366        this issue can be fixed by a performance optimization.
368    21. Change 33 of 8.34 is not sufficient to ensure stack safety because it does
369        not take account if existing stack usage. There is now a new global
370        variable called pcre_stack_guard that can be set to point to an external
371        function to check stack availability. It is called at the start of
372        processing every parenthesized group.
374    22. A typo in the code meant that in ungreedy mode the max/min qualifier
375        behaved like a min-possessive qualifier, and, for example, /a{1,3}b/U did
376        not match "ab".
378    23. When UTF was disabled, the JIT program reported some incorrect compile
379        errors. These messages are silenced now.
381    24. Experimental support for ARM-64 and MIPS-64 has been added to the JIT
382        compiler.
384    25. Change all the temporary files used in RunGrepTest to be different to those
385        used by RunTest so that the tests can be run simultaneously, for example by
386        "make -j check".
389    Version 8.34 15-December-2013
390    -----------------------------
392    1.  Add pcre[16|32]_jit_free_unused_memory to forcibly free unused JIT
393        executable memory. Patch inspired by Carsten Klein.
395    2.  ./configure --enable-coverage defined SUPPORT_GCOV in config.h, although
396        this macro is never tested and has no effect, because the work to support
397        coverage involves only compiling and linking options and special targets in
398        the Makefile. The comment in config.h implied that defining the macro would
399        enable coverage support, which is totally false. There was also support for
400        setting this macro in the CMake files (my fault, I just copied it from
401        configure). SUPPORT_GCOV has now been removed.
403    3.  Make a small performance improvement in strlen16() and strlen32() in
404        pcretest.
406    4.  Change 36 for 8.33 left some unreachable statements in pcre_exec.c,
407        detected by the Solaris compiler (gcc doesn't seem to be able to diagnose
408        these cases). There was also one in pcretest.c.
410    5.  Cleaned up a "may be uninitialized" compiler warning in pcre_exec.c.
412    6.  In UTF mode, the code for checking whether a group could match an empty
413        string (which is used for indefinitely repeated groups to allow for
414        breaking an infinite loop) was broken when the group contained a repeated
415        negated single-character class with a character that occupied more than one
416        data item and had a minimum repetition of zero (for example, [^\x{100}]* in
417        UTF-8 mode). The effect was undefined: the group might or might not be
418        deemed as matching an empty string, or the program might have crashed.
420    7.  The code for checking whether a group could match an empty string was not
421        recognizing that \h, \H, \v, \V, and \R must match a character.
423    8.  Implemented PCRE_INFO_MATCH_EMPTY, which yields 1 if the pattern can match
424        an empty string. If it can, pcretest shows this in its information output.
426    9.  Fixed two related bugs that applied to Unicode extended grapheme clusters
427        that were repeated with a maximizing qualifier (e.g. \X* or \X{2,5}) when
428        matched by pcre_exec() without using JIT:
430        (a) If the rest of the pattern did not match after a maximal run of
431            grapheme clusters, the code for backing up to try with fewer of them
432            did not always back up over a full grapheme when characters that do not
433            have the modifier quality were involved, e.g. Hangul syllables.
435        (b) If the match point in a subject started with modifier character, and
436            there was no match, the code could incorrectly back up beyond the match
437            point, and potentially beyond the first character in the subject,
438            leading to a segfault or an incorrect match result.
440    10. A conditional group with an assertion condition could lead to PCRE
441        recording an incorrect first data item for a match if no other first data
442        item was recorded. For example, the pattern (?(?=ab)ab) recorded "a" as a
443        first data item, and therefore matched "ca" after "c" instead of at the
444        start.
446    11. Change 40 for 8.33 (allowing pcregrep to find empty strings) showed up a
447        bug that caused the command "echo a | ./pcregrep -M '|a'" to loop.
449    12. The source of pcregrep now includes z/OS-specific code so that it can be
450        compiled for z/OS as part of the special z/OS distribution.
452    13. Added the -T and -TM options to pcretest.
454    14. The code in pcre_compile.c for creating the table of named capturing groups
455        has been refactored. Instead of creating the table dynamically during the
456        actual compiling pass, the information is remembered during the pre-compile
457        pass (on the stack unless there are more than 20 named groups, in which
458        case malloc() is used) and the whole table is created before the actual
459        compile happens. This has simplified the code (it is now nearly 150 lines
460        shorter) and prepared the way for better handling of references to groups
461        with duplicate names.
463    15. A back reference to a named subpattern when there is more than one of the
464        same name now checks them in the order in which they appear in the pattern.
465        The first one that is set is used for the reference. Previously only the
466        first one was inspected. This change makes PCRE more compatible with Perl.
468    16. Unicode character properties were updated from Unicode 6.3.0.
470    17. The compile-time code for auto-possessification has been refactored, based
471        on a patch by Zoltan Herczeg. It now happens after instead of during
472        compilation. The code is cleaner, and more cases are handled. The option
473        PCRE_NO_AUTO_POSSESS is added for testing purposes, and the -O and /O
474        options in pcretest are provided to set it. It can also be set by
475        (*NO_AUTO_POSSESS) at the start of a pattern.
477    18. The character VT has been added to the default ("C" locale) set of
478        characters that match \s and are generally treated as white space,
479        following this same change in Perl 5.18. There is now no difference between
480        "Perl space" and "POSIX space". Whether VT is treated as white space in
481        other locales depends on the locale.
483    19. The code for checking named groups as conditions, either for being set or
484        for being recursed, has been refactored (this is related to 14 and 15
485        above). Processing unduplicated named groups should now be as fast at
486        numerical groups, and processing duplicated groups should be faster than
487        before.
489    20. Two patches to the CMake build system, by Alexander Barkov:
491          (1) Replace the "source" command by "." in CMakeLists.txt because
492              "source" is a bash-ism.
494          (2) Add missing HAVE_STDINT_H and HAVE_INTTYPES_H to config-cmake.h.in;
495              without these the CMake build does not work on Solaris.
497    21. Perl has changed its handling of \8 and \9. If there is no previously
498        encountered capturing group of those numbers, they are treated as the
499        literal characters 8 and 9 instead of a binary zero followed by the
500        literals. PCRE now does the same.
502    22. Following Perl, added \o{} to specify codepoints in octal, making it
503        possible to specify values greater than 0777 and also making them
504        unambiguous.
506    23. Perl now gives an error for missing closing braces after \x{... instead of
507        treating the string as literal. PCRE now does the same.
509    24. RunTest used to grumble if an inappropriate test was selected explicitly,
510        but just skip it when running all tests. This make it awkward to run ranges
511        of tests when one of them was inappropriate. Now it just skips any
512        inappropriate tests, as it always did when running all tests.
514    25. If PCRE_AUTO_CALLOUT and PCRE_UCP were set for a pattern that contained
515        character types such as \d or \w, too many callouts were inserted, and the
516        data that they returned was rubbish.
518    26. In UCP mode, \s was not matching two of the characters that Perl matches,
519        namely NEL (U+0085) and MONGOLIAN VOWEL SEPARATOR (U+180E), though they
520        were matched by \h. The code has now been refactored so that the lists of
521        the horizontal and vertical whitespace characters used for \h and \v (which
522        are defined only in one place) are now also used for \s.
524    27. Add JIT support for the 64 bit TileGX architecture.
525        Patch by Jiong Wang (Tilera Corporation).
527    28. Possessive quantifiers for classes (both explicit and automatically
528        generated) now use special opcodes instead of wrapping in ONCE brackets.
530    29. Whereas an item such as A{4}+ ignored the possessivenes of the quantifier
531        (because it's meaningless), this was not happening when PCRE_CASELESS was
532        set. Not wrong, but inefficient.
534    30. Updated perltest.pl to add /u (force Unicode mode) when /W (use Unicode
535        properties for \w, \d, etc) is present in a test regex. Otherwise if the
536        test contains no characters greater than 255, Perl doesn't realise it
537        should be using Unicode semantics.
539    31. Upgraded the handling of the POSIX classes [:graph:], [:print:], and
540        [:punct:] when PCRE_UCP is set so as to include the same characters as Perl
541        does in Unicode mode.
543    32. Added the "forbid" facility to pcretest so that putting tests into the
544        wrong test files can sometimes be quickly detected.
546    33. There is now a limit (default 250) on the depth of nesting of parentheses.
547        This limit is imposed to control the amount of system stack used at compile
548        time. It can be changed at build time by --with-parens-nest-limit=xxx or
549        the equivalent in CMake.
551    34. Character classes such as [A-\d] or [a-[:digit:]] now cause compile-time
552        errors. Perl warns for these when in warning mode, but PCRE has no facility
553        for giving warnings.
555    35. Change 34 for 8.13 allowed quantifiers on assertions, because Perl does.
556        However, this was not working for (?!) because it is optimized to (*FAIL),
557        for which PCRE does not allow quantifiers. The optimization is now disabled
558        when a quantifier follows (?!). I can't see any use for this, but it makes
559        things uniform.
561    36. Perl no longer allows group names to start with digits, so I have made this
562        change also in PCRE. It simplifies the code a bit.
564    37. In extended mode, Perl ignores spaces before a + that indicates a
565        possessive quantifier. PCRE allowed a space before the quantifier, but not
566        before the possessive +. It now does.
568    38. The use of \K (reset reported match start) within a repeated possessive
569        group such as (a\Kb)*+ was not working.
571    40. Document that the same character tables must be used at compile time and
572        run time, and that the facility to pass tables to pcre_exec() and
573        pcre_dfa_exec() is for use only with saved/restored patterns.
575    41. Applied Jeff Trawick's patch CMakeLists.txt, which "provides two new
576        features for Builds with MSVC:
578        1. Support pcre.rc and/or pcreposix.rc (as is already done for MinGW
579           builds). The .rc files can be used to set FileDescription and many other
580           attributes.
582        2. Add an option (-DINSTALL_MSVC_PDB) to enable installation of .pdb files.
583           This allows higher-level build scripts which want .pdb files to avoid
584           hard-coding the exact files needed."
586    42. Added support for [[:<:]] and [[:>:]] as used in the BSD POSIX library to
587        mean "start of word" and "end of word", respectively, as a transition aid.
589    43. A minimizing repeat of a class containing codepoints greater than 255 in
590        non-UTF 16-bit or 32-bit modes caused an internal error when PCRE was
591        compiled to use the heap for recursion.
593    44. Got rid of some compiler warnings for unused variables when UTF but not UCP
594        is configured.
597    Version 8.33 28-May-2013
598    ------------------------
600    1.  Added 'U' to some constants that are compared to unsigned integers, to
601        avoid compiler signed/unsigned warnings. Added (int) casts to unsigned
602        variables that are added to signed variables, to ensure the result is
603        signed and can be negated.
605    2.  Applied patch by Daniel Richard G for quashing MSVC warnings to the
606        CMake config files.
608    3.  Revise the creation of config.h.generic so that all boolean macros are
609        #undefined, whereas non-boolean macros are #ifndef/#endif-ed. This makes
610        overriding via -D on the command line possible.
612    4.  Changing the definition of the variable "op" in pcre_exec.c from pcre_uchar
613        to unsigned int is reported to make a quite noticeable speed difference in
614        a specific Windows environment. Testing on Linux did also appear to show
615        some benefit (and it is clearly not harmful). Also fixed the definition of
616        Xop which should be unsigned.
618    5.  Related to (4), changing the definition of the intermediate variable cc
619        in repeated character loops from pcre_uchar to pcre_uint32 also gave speed
620        improvements.
622    6.  Fix forward search in JIT when link size is 3 or greater. Also removed some
623        unnecessary spaces.
625    7.  Adjust autogen.sh and configure.ac to lose warnings given by automake 1.12
626        and later.
628    8.  Fix two buffer over read issues in 16 and 32 bit modes. Affects JIT only.
630    9.  Optimizing fast_forward_start_bits in JIT.
632    10. Adding support for callouts in JIT, and fixing some issues revealed
633        during this work. Namely:
635        (a) Unoptimized capturing brackets incorrectly reset on backtrack.
637        (b) Minimum length was not checked before the matching is started.
639    11. The value of capture_last that is passed to callouts was incorrect in some
640        cases when there was a capture on one path that was subsequently abandoned
641        after a backtrack. Also, the capture_last value is now reset after a
642        recursion, since all captures are also reset in this case.
644    12. The interpreter no longer returns the "too many substrings" error in the
645        case when an overflowing capture is in a branch that is subsequently
646        abandoned after a backtrack.
648    13. In the pathological case when an offset vector of size 2 is used, pcretest
649        now prints out the matched string after a yield of 0 or 1.
651    14. Inlining subpatterns in recursions, when certain conditions are fulfilled.
652        Only supported by the JIT compiler at the moment.
654    15. JIT compiler now supports 32 bit Macs thanks to Lawrence Velazquez.
656    16. Partial matches now set offsets[2] to the "bumpalong" value, that is, the
657        offset of the starting point of the matching process, provided the offsets
658        vector is large enough.
660    17. The \A escape now records a lookbehind value of 1, though its execution
661        does not actually inspect the previous character. This is to ensure that,
662        in partial multi-segment matching, at least one character from the old
663        segment is retained when a new segment is processed. Otherwise, if there
664        are no lookbehinds in the pattern, \A might match incorrectly at the start
665        of a new segment.
667    18. Added some #ifdef __VMS code into pcretest.c to help VMS implementations.
669    19. Redefined some pcre_uchar variables in pcre_exec.c as pcre_uint32; this
670        gives some modest performance improvement in 8-bit mode.
672    20. Added the PCRE-specific property \p{Xuc} for matching characters that can
673        be expressed in certain programming languages using Universal Character
674        Names.
676    21. Unicode validation has been updated in the light of Unicode Corrigendum #9,
677        which points out that "non characters" are not "characters that may not
678        appear in Unicode strings" but rather "characters that are reserved for
679        internal use and have only local meaning".
681    22. When a pattern was compiled with automatic callouts (PCRE_AUTO_CALLOUT) and
682        there was a conditional group that depended on an assertion, if the
683        assertion was false, the callout that immediately followed the alternation
684        in the condition was skipped when pcre_exec() was used for matching.
686    23. Allow an explicit callout to be inserted before an assertion that is the
687        condition for a conditional group, for compatibility with automatic
688        callouts, which always insert a callout at this point.
690    24. In 8.31, (*COMMIT) was confined to within a recursive subpattern. Perl also
691        confines (*SKIP) and (*PRUNE) in the same way, and this has now been done.
693    25. (*PRUNE) is now supported by the JIT compiler.
695    26. Fix infinite loop when /(?<=(*SKIP)ac)a/ is matched against aa.
697    27. Fix the case where there are two or more SKIPs with arguments that may be
698        ignored.
700    28. (*SKIP) is now supported by the JIT compiler.
702    29. (*THEN) is now supported by the JIT compiler.
704    30. Update RunTest with additional test selector options.
706    31. The way PCRE handles backtracking verbs has been changed in two ways.
708        (1) Previously, in something like (*COMMIT)(*SKIP), COMMIT would override
709        SKIP. Now, PCRE acts on whichever backtracking verb is reached first by
710        backtracking. In some cases this makes it more Perl-compatible, but Perl's
711        rather obscure rules do not always do the same thing.
713        (2) Previously, backtracking verbs were confined within assertions. This is
714        no longer the case for positive assertions, except for (*ACCEPT). Again,
715        this sometimes improves Perl compatibility, and sometimes does not.
717    32. A number of tests that were in test 2 because Perl did things differently
718        have been moved to test 1, because either Perl or PCRE has changed, and
719        these tests are now compatible.
721    32. Backtracking control verbs are now handled in the same way in JIT and
722        interpreter.
724    33. An opening parenthesis in a MARK/PRUNE/SKIP/THEN name in a pattern that
725        contained a forward subroutine reference caused a compile error.
727    34. Auto-detect and optimize limited repetitions in JIT.
729    35. Implement PCRE_NEVER_UTF to lock out the use of UTF, in particular,
730        blocking (*UTF) etc.
732    36. In the interpreter, maximizing pattern repetitions for characters and
733        character types now use tail recursion, which reduces stack usage.
735    37. The value of the max lookbehind was not correctly preserved if a compiled
736        and saved regex was reloaded on a host of different endianness.
738    38. Implemented (*LIMIT_MATCH) and (*LIMIT_RECURSION). As part of the extension
739        of the compiled pattern block, expand the flags field from 16 to 32 bits
740        because it was almost full.
742    39. Try madvise first before posix_madvise.
744    40. Change 7 for PCRE 7.9 made it impossible for pcregrep to find empty lines
745        with a pattern such as ^$. It has taken 4 years for anybody to notice! The
746        original change locked out all matches of empty strings. This has been
747        changed so that one match of an empty string per line is recognized.
748        Subsequent searches on the same line (for colouring or for --only-matching,
749        for example) do not recognize empty strings.
751    41. Applied a user patch to fix a number of spelling mistakes in comments.
753    42. Data lines longer than 65536 caused pcretest to crash.
755    43. Clarified the data type for length and startoffset arguments for pcre_exec
756        and pcre_dfa_exec in the function-specific man pages, where they were
757        explicitly stated to be in bytes, never having been updated. I also added
758        some clarification to the pcreapi man page.
760    44. A call to pcre_dfa_exec() with an output vector size less than 2 caused
761        a segmentation fault.
764    Version 8.32 30-November-2012
765    -----------------------------
767    1.  Improved JIT compiler optimizations for first character search and single
768        character iterators.
770    2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
771        Patch by Daniel Richard G.
773    3.  Single character iterator optimizations in the JIT compiler.
775    4.  Improved JIT compiler optimizations for character ranges.
777    5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
778        Reported by Giuseppe D'Angelo.
780    6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
781        of a line, was being set incorrectly in cases where .* appeared inside
782        atomic brackets at the start of a pattern, or where there was a subsequent
783        *PRUNE or *SKIP.
785    7.  Improved instruction cache flush for POWER/PowerPC.
786        Patch by Daniel Richard G.
788    8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
789        grep:
791        (a) There is now no limit to the number of patterns to be matched.
793        (b) An error is given if a pattern is too long.
795        (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
796            are now supported.
798        (d) --exclude-from and --include-from (multiple use) have been added.
800        (e) Exclusions and inclusions now apply to all files and directories, not
801            just to those obtained from scanning a directory recursively.
803        (f) Multiple uses of -f and --file-list are now supported.
805        (g) In a Windows environment, the default for -d has been changed from
806            "read" (the GNU grep default) to "skip", because otherwise the presence
807            of a directory in the file list provokes an error.
809        (h) The documentation has been revised and clarified in places.
811    9.  Improve the matching speed of capturing brackets.
813    10. Changed the meaning of \X so that it now matches a Unicode extended
814        grapheme cluster.
816    11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
817        out POSIX threads when JIT support is configured.
819    12. Added support for PCRE_STUDY_EXTRA_NEEDED.
821    13. In the POSIX wrapper regcomp() function, setting re_nsub field in the preg
822        structure could go wrong in environments where size_t is not the same size
823        as int.
825    14. Applied user-supplied patch to pcrecpp.cc to allow PCRE_NO_UTF8_CHECK to be
826        set.
828    15. The EBCDIC support had decayed; later updates to the code had included
829        explicit references to (e.g.) \x0a instead of CHAR_LF. There has been a
830        general tidy up of EBCDIC-related issues, and the documentation was also
831        not quite right. There is now a test that can be run on ASCII systems to
832        check some of the EBCDIC-related things (but is it not a full test).
834    16. The new PCRE_STUDY_EXTRA_NEEDED option is now used by pcregrep, resulting
835        in a small tidy to the code.
837    17. Fix JIT tests when UTF is disabled and both 8 and 16 bit mode are enabled.
839    18. If the --only-matching (-o) option in pcregrep is specified multiple
840        times, each one causes appropriate output. For example, -o1 -o2 outputs the
841        substrings matched by the 1st and 2nd capturing parentheses. A separating
842        string can be specified by --om-separator (default empty).
844    19. Improving the first n character searches.
846    20. Turn case lists for horizontal and vertical white space into macros so that
847        they are defined only once.
849    21. This set of changes together give more compatible Unicode case-folding
850        behaviour for characters that have more than one other case when UCP
851        support is available.
853        (a) The Unicode property table now has offsets into a new table of sets of
854            three or more characters that are case-equivalent. The MultiStage2.py
855            script that generates these tables (the pcre_ucd.c file) now scans
856            CaseFolding.txt instead of UnicodeData.txt for character case
857            information.
859        (b) The code for adding characters or ranges of characters to a character
860            class has been abstracted into a generalized function that also handles
861            case-independence. In UTF-mode with UCP support, this uses the new data
862            to handle characters with more than one other case.
864        (c) A bug that is fixed as a result of (b) is that codepoints less than 256
865            whose other case is greater than 256 are now correctly matched
866            caselessly. Previously, the high codepoint matched the low one, but not
867            vice versa.
869        (d) The processing of \h, \H, \v, and \ in character classes now makes use
870            of the new class addition function, using character lists defined as
871            macros alongside the case definitions of 20 above.
873        (e) Caseless back references now work with characters that have more than
874            one other case.
876        (f) General caseless matching of characters with more than one other case
877            is supported.
879    22. Unicode character properties were updated from Unicode 6.2.0
881    23. Improved CMake support under Windows. Patch by Daniel Richard G.
883    24. Add support for 32-bit character strings, and UTF-32
885    25. Major JIT compiler update (code refactoring and bugfixing).
886        Experimental Sparc 32 support is added.
888    26. Applied a modified version of Daniel Richard G's patch to create
889        pcre.h.generic and config.h.generic by "make" instead of in the
890        PrepareRelease script.
892    27. Added a definition for CHAR_NULL (helpful for the z/OS port), and use it in
893        pcre_compile.c when checking for a zero character.
895    28. Introducing a native interface for JIT. Through this interface, the compiled
896        machine code can be directly executed. The purpose of this interface is to
897        provide fast pattern matching, so several sanity checks are not performed.
898        However, feature tests are still performed. The new interface provides
899        1.4x speedup compared to the old one.
901    29. If pcre_exec() or pcre_dfa_exec() was called with a negative value for
902        the subject string length, the error given was PCRE_ERROR_BADOFFSET, which
903        was confusing. There is now a new error PCRE_ERROR_BADLENGTH for this case.
905    30. In 8-bit UTF-8 mode, pcretest failed to give an error for data codepoints
906        greater than 0x7fffffff (which cannot be represented in UTF-8, even under
907        the "old" RFC 2279). Instead, it ended up passing a negative length to
908        pcre_exec().
910    31. Add support for GCC's visibility feature to hide internal functions.
912    32. Running "pcretest -C pcre8" or "pcretest -C pcre16" gave a spurious error
913        "unknown -C option" after outputting 0 or 1.
915    33. There is now support for generating a code coverage report for the test
916        suite in environments where gcc is the compiler and lcov is installed. This
917        is mainly for the benefit of the developers.
919    34. If PCRE is built with --enable-valgrind, certain memory regions are marked
920        unaddressable using valgrind annotations, allowing valgrind to detect
921        invalid memory accesses. This is mainly for the benefit of the developers.
923    25. (*UTF) can now be used to start a pattern in any of the three libraries.
925    26. Give configure error if --enable-cpp but no C++ compiler found.
928    Version 8.31 06-July-2012
929    -------------------------
931    1.  Fixing a wrong JIT test case and some compiler warnings.
933    2.  Removed a bashism from the RunTest script.
935    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
936        to unsigned type, result still unsigned" that was given by an MS compiler
937        on encountering the code "-sizeof(xxx)".
939    4.  Partial matching support is added to the JIT compiler.
941    5.  Fixed several bugs concerned with partial matching of items that consist
942        of more than one character:
944        (a) /^(..)\1/ did not partially match "aba" because checking references was
945            done on an "all or nothing" basis. This also applied to repeated
946            references.
948        (b) \R did not give a hard partial match if \r was found at the end of the
949            subject.
951        (c) \X did not give a hard partial match after matching one or more
952            characters at the end of the subject.
954        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
955            a partial match for the string "\r".
957        (e) When newline was set to CRLF, the metacharacter "." did not recognize
958            a partial match for a CR character at the end of the subject string.
960    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
961        running pcretest, the text "(JIT)" added to the output whenever JIT is
962        actually used to run the match.
964    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
965        or /S+[+] with a digit between 1 and 7.
967    8.  OP_NOT now supports any UTF character not just single-byte ones.
969    9.  (*MARK) control verb is now supported by the JIT compiler.
971    10. The command "./RunTest list" lists the available tests without actually
972        running any of them. (Because I keep forgetting what they all are.)
976    12. Applied a (slightly modified) user-supplied patch that improves performance
977        when the heap is used for recursion (compiled with --disable-stack-for-
978        recursion). Instead of malloc and free for each heap frame each time a
979        logical recursion happens, frames are retained on a chain and re-used where
980        possible. This sometimes gives as much as 30% improvement.
982    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
983        call.
985    14. As documented, (*COMMIT) is now confined to within a positive assertion.
987    15. It is now possible to link pcretest with libedit as an alternative to
988        libreadline.
990    16. (*COMMIT) control verb is now supported by the JIT compiler.
992    17. The Unicode data tables have been updated to Unicode 6.1.0.
994    18. Added --file-list option to pcregrep.
996    19. Added binary file support to pcregrep, including the -a, --binary-files,
997        -I, and --text options.
999    20. The madvise function is renamed for posix_madvise for QNX compatibility
1000        reasons. Fixed by Giuseppe D'Angelo.
1002    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
1004    22. Changed the option for creating symbolic links for 16-bit man pages from
1005        -s to -sf so that re-installing does not cause issues.
1007    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
1009    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
1010        matches in certain environments (the workspace was not being correctly
1011        retained). Also added to pcre_dfa_exec() a simple plausibility check on
1012        some of the workspace data at the beginning of a restart.
1014    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
1015        was not doing so when it should - probably a typo introduced by SVN 528
1016        (change 8.10/14).
1018    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
1019        \w+ when the character tables indicated that \x{c4} was a word character.
1020        There were several related cases, all because the tests for doing a table
1021        lookup were testing for characters less than 127 instead of 255.
1023    27. If a pattern contains capturing parentheses that are not used in a match,
1024        their slots in the ovector are set to -1. For those that are higher than
1025        any matched groups, this happens at the end of processing. In the case when
1026        there were back references that the ovector was too small to contain
1027        (causing temporary malloc'd memory to be used during matching), and the
1028        highest capturing number was not used, memory off the end of the ovector
1029        was incorrectly being set to -1. (It was using the size of the temporary
1030        memory instead of the true size.)
1032    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
1033        ovector size, it uses memory at the end of the block that it has got.
1035    29. Check for an overlong MARK name and give an error at compile time. The
1036        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
1038    30. JIT compiler update.
1040    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
1041        Rill for the patch.
1043    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
1045    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
1047    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
1048        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
1049        was enabled.
1051    35. Improve JIT code generation for greedy plus quantifier.
1053    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
1054        1 to "aa" instead of to an empty string. The bug affected repeated groups
1055        that could potentially match an empty string.
1057    37. Optimizing single character iterators in JIT.
1059    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
1060        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
1061        codepoints that are too big for the mode are faulted, and in a UTF mode,
1062        disallowed codepoints are also faulted.
1064    39. If PCRE was compiled with UTF support, in three places in the DFA
1065        matcher there was code that should only have been obeyed in UTF mode, but
1066        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
1067        processing when bytes with values greater than 127 were present. In 16-bit
1068        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
1069        both cases the values are those that cannot be the first data item in a UTF
1070        character. The three items that might have provoked this were recursions,
1071        possessively repeated groups, and atomic groups.
1073    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
1074        and pcregrep, because some OS require shared objects to be explicitly
1075        passed to ld, causing the link step to fail if they are not.
1077    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
1078        mode, patterns that started with \h* or \R* might be incorrectly matched.
1081    Version 8.30 04-February-2012
1082    -----------------------------
1084    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
1085        name is defined in ctype.h.
1087    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
1088        only in quite long subpatterns.
1090    3.  Removed the function pcre_info(), which has been obsolete and deprecated
1091        since it was replaced by pcre_fullinfo() in February 2000.
1093    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
1094        match a (*MARK), and the match failed at the start of the subject, a
1095        reference to memory before the start of the subject could occur. This bug
1096        was introduced by fix 17 of release 8.21.
1098    5.  A reference to an unset group with zero minimum repetition was giving
1099        totally wrong answers (in non-JavaScript-compatibility mode). For example,
1100        /(another)?(\1?)test/ matched against "hello world test". This bug was
1101        introduced in release 8.13.
1103    6.  Add support for 16-bit character strings (a large amount of work involving
1104        many changes and refactorings).
1106    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
1107        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
1108        from a file.
1110    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
1111        rounding is not applied in this particular case).
1113    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
1114        if they appear, or are escaped, in patterns.
1116    10. Get rid of a number of -Wunused-but-set-variable warnings.
1118    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
1119        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
1120        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
1121        also returns the mark "x". This bug applied to capturing parentheses,
1122        non-capturing parentheses, and atomic parentheses. It also applied to some
1123        assertions.
1125    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
1126        information out of configure.ac instead of relying on pcre.h.generic, which
1127        is not stored in the repository.
1129    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
1130        -lreadline.
1132    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
1134    15. Applied Graycode's patch to put the top-level frame on the stack rather
1135        than the heap when not using the stack for recursion. This gives a
1136        performance improvement in many cases when recursion is not deep.
1138    16. Experimental code added to "pcretest -C" to output the stack frame size.
1141    Version 8.21 12-Dec-2011
1142    ------------------------
1144    1.  Updating the JIT compiler.
1146    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
1147        are added as well.
1149    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
1150        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
1151        calling _pcre_jit_exec. Some extra comments are added.
1153    4.  (*MARK) settings inside atomic groups that do not contain any capturing
1154        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
1155        was introduced by change 18 for 8.20.
1157    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
1158        ECMA-262 standard.
1160    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
1161        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
1162        This bug was probably introduced by change 9 of 8.13.
1164    7.  While fixing 6 above, I noticed that a number of other items were being
1165        incorrectly rejected as "not fixed length". This arose partly because newer
1166        opcodes had not been added to the fixed-length checking code. I have (a)
1167        corrected the bug and added tests for these items, and (b) arranged for an
1168        error to occur if an unknown opcode is encountered while checking for fixed
1169        length instead of just assuming "not fixed length". The items that were
1170        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
1171        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
1172        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
1174    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
1175        being incorrectly compiled and would have given unpredicatble results.
1177    9.  A possessively repeated subpattern with minimum repeat count greater than
1178        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
1179        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
1180        the first (A) could occur when it should not.
1182    10. Add a cast and remove a redundant test from the code.
1184    11. JIT should use pcre_malloc/pcre_free for allocation.
1186    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
1187        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
1188        is anything other than /usr, -L is still shown).
1190    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
1192    14. Perl does not support \N without a following name in a [] class; PCRE now
1193        also gives an error.
1195    15. If a forward reference was repeated with an upper limit of around 2000,
1196        it caused the error "internal error: overran compiling workspace". The
1197        maximum number of forward references (including repeats) was limited by the
1198        internal workspace, and dependent on the LINK_SIZE. The code has been
1199        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
1200        the default depends on LINK_SIZE. There is a new upper limit (for safety)
1201        of around 200,000 forward references. While doing this, I also speeded up
1202        the filling in of repeated forward references.
1204    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
1205        incorrectly expecting the subject to contain another "a" after the start.
1207    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
1208        in the match, the SKIP should be ignored. This was not happening; instead
1209        the SKIP was being treated as NOMATCH. For patterns such as
1210        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
1211        tested.
1213    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
1214        now much more compatible with Perl, in particular in cases where the result
1215        is a non-match for a non-anchored pattern. For example, if
1216        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
1217        "m", where previously it did not return a name. A side effect of this
1218        change is that for partial matches, the last encountered mark name is
1219        returned, as for non matches. A number of tests that were previously not
1220        Perl-compatible have been moved into the Perl-compatible test files. The
1221        refactoring has had the pleasing side effect of removing one argument from
1222        the match() function, thus reducing its stack requirements.
1224    19. If the /S+ option was used in pcretest to study a pattern using JIT,
1225        subsequent uses of /S (without +) incorrectly behaved like /S+.
1227    21. Retrieve executable code size support for the JIT compiler and fixing
1228        some warnings.
1230    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
1231        not work when the shorter character appeared right at the end of the
1232        subject string.
1234    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
1235        systems.
1237    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
1238        output it when the /M option is used in pcretest.
1240    25. The CheckMan script was not being included in the distribution. Also, added
1241        an explicit "perl" to run Perl scripts from the PrepareRelease script
1242        because this is reportedly needed in Windows.
1244    26. If study data was being save in a file and studying had not found a set of
1245        "starts with" bytes for the pattern, the data written to the file (though
1246        never used) was taken from uninitialized memory and so caused valgrind to
1247        complain.
1249    27. Updated RunTest.bat as provided by Sheri Pierce.
1251    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
1253    29. Computation of memory usage for the table of capturing group names was
1254        giving an unnecessarily large value.
1257    Version 8.20 21-Oct-2011
1258    ------------------------
1260    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
1261        a POSIX class. After further experiments with Perl, which convinced me that
1262        Perl has bugs and confusions, a closing square bracket is no longer allowed
1263        in a POSIX name. This bug also affected patterns with classes that started
1264        with full stops.
1266    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
1267        captured substring, but while checking the failing first alternative,
1268        substring 1 is temporarily captured. If the output vector supplied to
1269        pcre_exec() was not big enough for this capture, the yield of the function
1270        was still zero ("insufficient space for captured substrings"). This cannot
1271        be totally fixed without adding another stack variable, which seems a lot
1272        of expense for a edge case. However, I have improved the situation in cases
1273        such as /(a)(b)x|abc/ matched against "abc", where the return code
1274        indicates that fewer than the maximum number of slots in the ovector have
1275        been set.
1277    3.  Related to (2) above: when there are more back references in a pattern than
1278        slots in the output vector, pcre_exec() uses temporary memory during
1279        matching, and copies in the captures as far as possible afterwards. It was
1280        using the entire output vector, but this conflicts with the specification
1281        that only 2/3 is used for passing back captured substrings. Now it uses
1282        only the first 2/3, for compatibility. This is, of course, another edge
1283        case.
1285    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
1286        main code base, and can be used by building with --enable-jit. When this is
1287        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
1288        runtime --no-jit option is given.
1290    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
1291        ovector, the return from the function was zero, implying that there were
1292        other matches that did not fit. The correct "exactly full" value is now
1293        returned.
1295    6.  If a subpattern that was called recursively or as a subroutine contained
1296        (*PRUNE) or any other control that caused it to give a non-standard return,
1297        invalid errors such as "Error -26 (nested recursion at the same subject
1298        position)" or even infinite loops could occur.
1300    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
1301        computing the minimum length on reaching *ACCEPT, and so ended up with the
1302        wrong value of 1 rather than 0. Further investigation indicates that
1303        computing a minimum subject length in the presence of *ACCEPT is difficult
1304        (think back references, subroutine calls), and so I have changed the code
1305        so that no minimum is registered for a pattern that contains *ACCEPT.
1307    8.  If (*THEN) was present in the first (true) branch of a conditional group,
1308        it was not handled as intended. [But see 16 below.]
1310    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
1311        Sheri Pierce.
1313    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
1314        the first byte in a match must be "a".
1316    11. Change 17 for 8.13 increased the recursion depth for patterns like
1317        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
1318        pattern contains any instances of (*THEN). If it does not, the old
1319        optimizations are restored. It would be nice to do this on a per-group
1320        basis, but at the moment that is not feasible.
1322    12. In some environments, the output of pcretest -C is CRLF terminated. This
1323        broke RunTest's code that checks for the link size. A single white space
1324        character after the value is now allowed for.
1326    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
1327        For "fr", it uses the Windows-specific input and output files.
1329    14. If (*THEN) appeared in a group that was called recursively or as a
1330        subroutine, it did not work as intended. [But see next item.]
1332    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
1333        pattern fragments (but not containing any | characters). If A and B are
1334        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
1335        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
1336        D. In other words, Perl considers parentheses that do not contain any |
1337        characters to be part of a surrounding alternative, whereas PCRE was
1338        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
1339        differently. PCRE now behaves in the same way as Perl, except in the case
1340        of subroutine/recursion calls such as (?1) which have in any case always
1341        been different (but PCRE had them first :-).
1343    16. Related to 15 above: Perl does not treat the | in a conditional group as
1344        creating alternatives. Such a group is treated in the same way as an
1345        ordinary group without any | characters when processing (*THEN). PCRE has
1346        been changed to match Perl's behaviour.
1348    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
1349        RunGrepTest script failed.
1351    18. Change 22 for version 13 caused atomic groups to use more stack. This is
1352        inevitable for groups that contain captures, but it can lead to a lot of
1353        stack use in large patterns. The old behaviour has been restored for atomic
1354        groups that do not contain any capturing parentheses.
1356    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
1357        suppress the check for a minimum subject length at run time. (If it was
1358        given to pcre_exec() or pcre_dfa_exec() it did work.)
1360    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
1361        fail to work when decoding hex characters in data strings in EBCDIC
1362        environments.
1364    21. It appears that in at least one Mac OS environment, the isxdigit() function
1365        is implemented as a macro that evaluates to its argument more than once,
1366        contravening the C 90 Standard (I haven't checked a later standard). There
1367        was an instance in pcretest which caused it to go wrong when processing
1368        \x{...} escapes in subject strings. The has been rewritten to avoid using
1369        things like p++ in the argument of isxdigit().
1372    Version 8.13 16-Aug-2011
1373    ------------------------
1375    1.  The Unicode data tables have been updated to Unicode 6.0.0.
1377    2.  Two minor typos in pcre_internal.h have been fixed.
1379    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
1380        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
1381        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
1383    4.  There were a number of related bugs in the code for matching backrefences
1384        caselessly in UTF-8 mode when codes for the characters concerned were
1385        different numbers of bytes. For example, U+023A and U+2C65 are an upper
1386        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
1387        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
1388        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
1389        2-byte code at the end of the subject (it thought there wasn't enough data
1390        left).
1392    5.  Comprehensive information about what went wrong is now returned by
1393        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
1394        as the output vector has at least 2 elements. The offset of the start of
1395        the failing character and a reason code are placed in the vector.
1397    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
1398        now returned is for the first byte of the failing character, instead of the
1399        last byte inspected. This is an incompatible change, but I hope it is small
1400        enough not to be a problem. It makes the returned offset consistent with
1401        pcre_exec() and pcre_dfa_exec().
1403    7.  pcretest now gives a text phrase as well as the error number when
1404        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
1405        failure, the offset and reason code are output.
1407    8.  When \R was used with a maximizing quantifier it failed to skip backwards
1408        over a \r\n pair if the subsequent match failed. Instead, it just skipped
1409        back over a single character (\n). This seems wrong (because it treated the
1410        two characters as a single entity when going forwards), conflicts with the
1411        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
1412        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
1413        has been changed.
1415    9.  Some internal refactoring has changed the processing so that the handling
1416        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
1417        time (the PCRE_DOTALL option was changed this way some time ago: version
1418        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
1419        which was always a bit of a fudge. It also means that there is one less
1420        argument for the match() function, which reduces its stack requirements
1421        slightly. This change also fixes an incompatibility with Perl: the pattern
1422        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
1424    10. More internal refactoring has drastically reduced the number of recursive
1425        calls to match() for possessively repeated groups such as (abc)++ when
1426        using pcre_exec().
1428    11. While implementing 10, a number of bugs in the handling of groups were
1429        discovered and fixed:
1431        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
1432        (a|)*(?1) gave a compile-time internal error.
1433        ((a|)+)+  did not notice that the outer group could match an empty string.
1434        (^a|^)+   was not marked as anchored.
1435        (.*a|.*)+ was not marked as matching at start or after a newline.
1437    12. Yet more internal refactoring has removed another argument from the match()
1438        function. Special calls to this function are now indicated by setting a
1439        value in a variable in the "match data" data block.
1441    13. Be more explicit in pcre_study() instead of relying on "default" for
1442        opcodes that mean there is no starting character; this means that when new
1443        ones are added and accidentally left out of pcre_study(), testing should
1444        pick them up.
1446    14. The -s option of pcretest has been documented for ages as being an old
1447        synonym of -m (show memory usage). I have changed it to mean "force study
1448        for every regex", that is, assume /S for every regex. This is similar to -i
1449        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
1450        using it. It makes it easier to run collections of tests with and without
1451        study enabled, and thereby test pcre_study() more easily. All the standard
1452        tests are now run with and without -s (but some patterns can be marked as
1453        "never study" - see 20 below).
1455    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
1456        restoration of the capturing data to the outer values was not happening
1457        correctly.
1459    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
1460        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
1461        pattern had matched an empty string, and so incorrectly returned a no
1462        match.
1464    17. There was optimizing code for the last branch of non-capturing parentheses,
1465        and also for the obeyed branch of a conditional subexpression, which used
1466        tail recursion to cut down on stack usage. Unfortunately, now that there is
1467        the possibility of (*THEN) occurring in these branches, tail recursion is
1468        no longer possible because the return has to be checked for (*THEN). These
1469        two optimizations have therefore been removed. [But see 8.20/11 above.]
1471    18. If a pattern containing \R was studied, it was assumed that \R always
1472        matched two bytes, thus causing the minimum subject length to be
1473        incorrectly computed because \R can also match just one byte.
1475    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
1476        was incorrectly computed.
1478    20. If /S is present twice on a test pattern in pcretest input, it now
1479        *disables* studying, thereby overriding the use of -s on the command line
1480        (see 14 above). This is necessary for one or two tests to keep the output
1481        identical in both cases.
1483    21. When (*ACCEPT) was used in an assertion that matched an empty string and
1484        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
1486    22. When an atomic group that contained a capturing parenthesis was
1487        successfully matched, but the branch in which it appeared failed, the
1488        capturing was not being forgotten if a higher numbered group was later
1489        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
1490        group 1 to "a", when in fact it should be unset. This applied to multi-
1491        branched capturing and non-capturing groups, repeated or not, and also to
1492        positive assertions (capturing in negative assertions does not happen
1493        in PCRE) and also to nested atomic groups.
1495    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
1496        subject after a captured substring, to make it easier to tell which of a
1497        number of identical substrings has been captured.
1499    24. The way atomic groups are processed by pcre_exec() has been changed so that
1500        if they are repeated, backtracking one repetition now resets captured
1501        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
1502        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
1503        "aaa". Previously, it would have been "a". As part of this code
1504        refactoring, the way recursive calls are handled has also been changed.
1506    25. If an assertion condition captured any substrings, they were not passed
1507        back unless some other capturing happened later. For example, if
1508        (?(?=(a))a) was matched against "a", no capturing was returned.
1510    26. When studying a pattern that contained subroutine calls or assertions,
1511        the code for finding the minimum length of a possible match was handling
1512        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
1513        group 1 called group 2 while simultaneously a separate group 2 called group
1514        1). A stack overflow occurred in this case. I have fixed this by limiting
1515        the recursion depth to 10.
1517    27. Updated RunTest.bat in the distribution to the version supplied by Tom
1518        Fortmann. This supports explicit test numbers on the command line, and has
1519        argument validation and error reporting.
1521    28. An instance of \X with an unlimited repeat could fail if at any point the
1522        first character it looked at was a mark character.
1524    29. Some minor code refactoring concerning Unicode properties and scripts
1525        should reduce the stack requirement of match() slightly.
1527    30. Added the '=' option to pcretest to check the setting of unused capturing
1528        slots at the end of the pattern, which are documented as being -1, but are
1529        not included in the return count.
1531    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
1532        compiled something random. Now it gives a compile-time error (as does
1533        Perl).
1535    32. A *MARK encountered during the processing of a positive assertion is now
1536        recorded and passed back (compatible with Perl).
1538    33. If --only-matching or --colour was set on a pcregrep call whose pattern
1539        had alternative anchored branches, the search for a second match in a line
1540        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
1541        matched the line "0102" twice. The same bug affected patterns that started
1542        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
1543        twice.
1545    34. Previously, PCRE did not allow quantification of assertions. However, Perl
1546        does, and because of capturing effects, quantifying parenthesized
1547        assertions may at times be useful. Quantifiers are now allowed for
1548        parenthesized assertions.
1550    35. A minor code tidy in pcre_compile() when checking options for \R usage.
1552    36. \g was being checked for fancy things in a character class, when it should
1553        just be a literal "g".
1555    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
1556        appearance of a nested POSIX class supersedes an apparent external class.
1557        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
1558        unescaped square brackets may also appear as part of class names. For
1559        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
1560        more like Perl. (But see 8.20/1 above.)
1562    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
1563        was because it thought it was \N{name}, which is not supported).
1565    39. Add minix to OS list not supporting the -S option in pcretest.
1567    40. PCRE tries to detect cases of infinite recursion at compile time, but it
1568        cannot analyze patterns in sufficient detail to catch mutual recursions
1569        such as ((?1))((?2)). There is now a runtime test that gives an error if a
1570        subgroup is called recursively as a subpattern for a second time at the
1571        same position in the subject string. In previous releases this might have
1572        been caught by the recursion limit, or it might have run out of stack.
1574    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
1575        happen only once. PCRE was, however incorrectly giving a compile time error
1576        "recursive call could loop indefinitely" because it cannot analyze the
1577        pattern in sufficient detail. The compile time test no longer happens when
1578        PCRE is compiling a conditional subpattern, but actual runaway loops are
1579        now caught at runtime (see 40 above).
1581    42. It seems that Perl allows any characters other than a closing parenthesis
1582        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
1583        has been changed to be the same.
1585    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
1586        as not to get warnings when autogen.sh is called. Also changed
1587        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
1589    44. To help people who use pcregrep to scan files containing exceedingly long
1590        lines, the following changes have been made:
1592        (a) The default value of the buffer size parameter has been increased from
1593            8K to 20K. (The actual buffer used is three times this size.)
1595        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
1596            PCRE is built.
1598        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
1599            to be set at run time.
1601        (d) Numerical values in pcregrep options can be followed by K or M, for
1602            example --buffer-size=50K.
1604        (e) If a line being scanned overflows pcregrep's buffer, an error is now
1605            given and the return code is set to 2.
1607    45. Add a pointer to the latest mark to the callout data block.
1609    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
1610        partial match of an empty string instead of no match. This was specific to
1611        the use of ".".
1613    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
1614        complete match instead of a partial match. This bug was dependent on both
1615        the PCRE_UTF8 and PCRE_DOTALL options being set.
1617    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
1618        starting byte set, because \b was not being ignored.
1621    Version 8.12 15-Jan-2011
1622    ------------------------
1624    1.  Fixed some typos in the markup of the man pages, and wrote a script that
1625        checks for such things as part of the documentation building process.
1627    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
1628        --match-limit and --recursion-limit options (added for 8.11). In
1629        particular, this made one of the standard tests fail. (The integer value
1630        went into the wrong half of a long int.)
1632    3.  If the --colour option was given to pcregrep with -v (invert match), it
1633        did strange things, either producing crazy output, or crashing. It should,
1634        of course, ignore a request for colour when reporting lines that do not
1635        match.
1637    4.  Another pcregrep bug caused similar problems if --colour was specified with
1638        -M (multiline) and the pattern match finished with a line ending.
1640    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
1641        matched in multiline mode, the following line was shown as part of the
1642        match. This seems wrong, so I have changed it.
1644    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
1645        the check for further matches in the same line (so they could be coloured)
1646        to overrun the end of the current line. If another match was found, it was
1647        incorrectly shown (and then shown again when found in the next line).
1649    7.  If pcregrep was compiled under Windows, there was a reference to the
1650        function pcregrep_exit() before it was defined. I am assuming this was
1651        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
1652        reported by a user. I've moved the definition above the reference.
1655    Version 8.11 10-Dec-2010
1656    ------------------------
1658    1.  (*THEN) was not working properly if there were untried alternatives prior
1659        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
1660        backtracked to try for "b" instead of moving to the next alternative branch
1661        at the same level (in this case, to look for "c"). The Perl documentation
1662        is clear that when (*THEN) is backtracked onto, it goes to the "next
1663        alternative in the innermost enclosing group".
1665    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
1666        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
1667        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
1668        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
1669        (*THEN).
1671    3.  If \s appeared in a character class, it removed the VT character from
1672        the class, even if it had been included by some previous item, for example
1673        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
1674        of \s, but is part of the POSIX "space" class.)
1676    4.  A partial match never returns an empty string (because you can always
1677        match an empty string at the end of the subject); however the checking for
1678        an empty string was starting at the "start of match" point. This has been
1679        changed to the "earliest inspected character" point, because the returned
1680        data for a partial match starts at this character. This means that, for
1681        example, /(?<=abc)def/ gives a partial match for the subject "abc"
1682        (previously it gave "no match").
1684    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
1685        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
1686        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
1687        has an implication that the given string is incomplete (because a partial
1688        match is preferred over a full match). For this reason, these items now
1689        give a partial match in this situation. [Aside: previously, the one case
1690        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
1691        match rather than a full match, which was wrong by the old rules, but is
1692        now correct.]
1694    6.  There was a bug in the handling of #-introduced comments, recognized when
1695        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
1696        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
1697        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
1698        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
1699        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
1700        places in pcre_compile().
1702    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
1703        comments when looking ahead for named forward references to subpatterns,
1704        the only newline sequence it recognized was NL. It now handles newlines
1705        according to the set newline convention.
1707    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
1708        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
1709        cater for a lack of strerror(). These oversights have been fixed.
1711    9.  Added --match-limit and --recursion-limit to pcregrep.
1713    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
1715    11. When the -o option was used, pcregrep was setting a return code of 1, even
1716        when matches were found, and --line-buffered was not being honoured.
1718    12. Added an optional parentheses number to the -o and --only-matching options
1719        of pcregrep.
1721    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
1722        can match an empty string. The code to do it in pcretest and pcredemo
1723        needed fixing:
1725        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
1726            only one byte after an empty string match just before CRLF (this case
1727            just got forgotten; "any" and "anycrlf" were OK).
1729        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
1730            mode when an empty string match preceded an ASCII character followed by
1731            a non-ASCII character. (The code for advancing by one character rather
1732            than one byte was nonsense.)
1734        (c) The pcredemo.c sample program did not have any code at all to handle
1735            the cases when CRLF is a valid newline sequence.
1737    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
1738        as a starting offset was within the subject string. There is now a new
1739        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
1740        negative or greater than the length of the string. In order to test this,
1741        pcretest is extended to allow the setting of negative starting offsets.
1743    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
1744        starting offset points to the beginning of a UTF-8 character was
1745        unnecessarily clumsy. I tidied it up.
1747    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
1748        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
1750    17. Nobody had reported that the --include_dir option, which was added in
1751        release 7.7 should have been called --include-dir (hyphen, not underscore)
1752        for compatibility with GNU grep. I have changed it to --include-dir, but
1753        left --include_dir as an undocumented synonym, and the same for
1754        --exclude-dir, though that is not available in GNU grep, at least as of
1755        release 2.5.4.
1757    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
1758        characters from a string of bytes) have been redefined so as not to use
1759        loops, in order to improve performance in some environments. At the same
1760        time, I abstracted some of the common code into auxiliary macros to save
1761        repetition (this should not affect the compiled code).
1763    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
1764        compile-time error is now given if \c is not followed by an ASCII
1765        character, that is, a byte less than 128. (In EBCDIC mode, the code is
1766        different, and any byte value is allowed.)
1768    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
1769        START_OPTIMIZE option, which is now allowed at compile time - but just
1770        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
1771        to pcregrep and other applications that have no direct access to PCRE
1772        options. The new /Y option in pcretest sets this option when calling
1773        pcre_compile().
1775    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
1776        back references. Groups containing recursive back references were forced to
1777        be atomic by that change, but in the case of named groups, the amount of
1778        memory required was incorrectly computed, leading to "Failed: internal
1779        error: code overflow". This has been fixed.
1781    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
1782        pcretest.c, to avoid build problems in some Borland environments.
1785    Version 8.10 25-Jun-2010
1786  ------------------------  ------------------------
1788  1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and  1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
# Line 42  Version 8.10 03-Jun-2010 Line 1823  Version 8.10 03-Jun-2010
1823  11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was  11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
1824      studied, and the match started with a letter with a code point greater than      studied, and the match started with a letter with a code point greater than
1825      127 whose first byte was different to the first byte of the other case of      127 whose first byte was different to the first byte of the other case of
1826      the letter, the other case of this starting letter was not recognized      the letter, the other case of this starting letter was not recognized
1827      (#976).      (#976).
1829  12. If a pattern that was studied started with a repeated Unicode property  12. If a pattern that was studied started with a repeated Unicode property
# Line 68  Version 8.10 03-Jun-2010 Line 1849  Version 8.10 03-Jun-2010
1850  17. Added a check for running out of memory when PCRE is compiled with  17. Added a check for running out of memory when PCRE is compiled with
1851      --disable-stack-for-recursion (#990).      --disable-stack-for-recursion (#990).
1853  18. If the last data line in a file for pcretest does not have a newline on  18. If the last data line in a file for pcretest does not have a newline on
1854      the end, a newline was missing in the output.      the end, a newline was missing in the output.
1856    19. The default pcre_chartables.c file recognizes only ASCII characters (values
1857        less than 128) in its various bitmaps. However, there is a facility for
1858        generating tables according to the current locale when PCRE is compiled. It
1859        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
1860        characters, are recognized by isspace() and therefore were getting set in
1861        these tables, and indeed these tables seem to approximate to ISO 8859. This
1862        caused a problem in UTF-8 mode when pcre_study() was used to create a list
1863        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
1864        which of course cannot start UTF-8 characters. I have changed the code so
1865        that only real ASCII characters (less than 128) and the correct starting
1866        bytes for UTF-8 encodings are set for characters greater than 127 when in
1867        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
1868        altogether.)
1870    20. Added the /T option to pcretest so as to be able to run tests with non-
1871        standard character tables, thus making it possible to include the tests
1872        used for 19 above in the standard set of tests.
1874    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
1875        reference to a subpattern the other side of a comment that contains an
1876        opening parenthesis caused either an internal compiling error, or a
1877        reference to the wrong subpattern.
1880  Version 8.02 19-Mar-2010  Version 8.02 19-Mar-2010
# Line 465  Version 7.9 11-Apr-09 Line 2268  Version 7.9 11-Apr-09
2268  7.  A pattern that could match an empty string could cause pcregrep to loop; it  7.  A pattern that could match an empty string could cause pcregrep to loop; it
2269      doesn't make sense to accept an empty string match in pcregrep, so I have      doesn't make sense to accept an empty string match in pcregrep, so I have
2270      locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this      locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
2271      seems to be how GNU grep behaves.      seems to be how GNU grep behaves. [But see later change 40 for release
2272        8.33.]
2274  8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at  8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
2275      start or after a newline", because the conditional assertion was not being      start or after a newline", because the conditional assertion was not being
# Line 708  Version 7.7 07-May-08 Line 2512  Version 7.7 07-May-08
2512      containing () gave an internal compiling error instead of "reference to      containing () gave an internal compiling error instead of "reference to
2513      non-existent subpattern". Fortunately, when the pattern did exist, the      non-existent subpattern". Fortunately, when the pattern did exist, the
2514      compiled code was correct. (When scanning forwards to check for the      compiled code was correct. (When scanning forwards to check for the
2515      existencd of the subpattern, it was treating the data ']' as terminating      existence of the subpattern, it was treating the data ']' as terminating
2516      the class, so got the count wrong. When actually compiling, the reference      the class, so got the count wrong. When actually compiling, the reference
2517      was subsequently set up correctly.)      was subsequently set up correctly.)

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