1PERL5300DELTA(1)       Perl Programmers Reference Guide       PERL5300DELTA(1)
2
3
4

NAME

6       perl5300delta - what is new for perl v5.30.0
7

DESCRIPTION

9       This document describes differences between the 5.28.0 release and the
10       5.30.0 release.
11
12       If you are upgrading from an earlier release such as 5.26.0, first read
13       perl5280delta, which describes differences between 5.26.0 and 5.28.0.
14

Notice

16       sv_utf8_(downgrade|decode) are no longer marked as experimental.  [GH
17       #16822] <https://github.com/Perl/perl5/issues/16822>.
18

Core Enhancements

20   Limited variable length lookbehind in regular expression pattern matching
21       is now experimentally supported
22       Using a lookbehind assertion (like "(?<=foo?)" or "(?<!ba{1,9}r)"
23       previously would generate an error and refuse to compile.  Now it
24       compiles (if the maximum lookbehind is at most 255 characters), but
25       raises a warning in the new "experimental::vlb" warnings category.
26       This is to caution you that the precise behavior is subject to change
27       based on feedback from use in the field.
28
29       See "(?<=pattern)" in perlre and "(?<!pattern)" in perlre.
30
31   The upper limit "n" specifiable in a regular expression quantifier of the
32       form "{m,n}" has been doubled to 65534
33       The meaning of an unbounded upper quantifier "{m,}" remains unchanged.
34       It matches 2**31 - 1 times on most platforms, and more on ones where a
35       C language short variable is more than 4 bytes long.
36
37   Unicode 12.1 is supported
38       Because of a change in Unicode release cycles, Perl jumps from Unicode
39       10.0 in Perl 5.28 to Unicode 12.1 in Perl 5.30.
40
41       For details on the Unicode changes, see
42       <https://www.unicode.org/versions/Unicode11.0.0/> for 11.0;
43       <https://www.unicode.org/versions/Unicode12.0.0/> for 12.0; and
44       <https://www.unicode.org/versions/Unicode12.1.0/> for 12.1.  (Unicode
45       12.1 differs from 12.0 only in the addition of a single character, that
46       for the new Japanese era name.)
47
48       The Word_Break property, as in past Perl releases, remains tailored to
49       behave more in line with expectations of Perl users.  This means that
50       sequential runs of horizontal white space characters are not broken
51       apart, but kept as a single run.  Unicode 11 changed from past versions
52       to be more in line with Perl, but it left several white space
53       characters as causing breaks: TAB, NO BREAK SPACE, and FIGURE SPACE
54       (U+2007).  We have decided to continue to use the previous Perl
55       tailoring with regards to these.
56
57   Wildcards in Unicode property value specifications are now partially
58       supported
59       You can now do something like this in a regular expression pattern
60
61        qr! \p{nv= /(?x) \A [0-5] \z / }!
62
63       which matches all Unicode code points whose numeric value is between 0
64       and 5 inclusive.  So, it could match the Thai or Bengali digits whose
65       numeric values are 0, 1, 2, 3, 4, or 5.
66
67       This marks another step in implementing the regular expression features
68       the Unicode Consortium suggests.
69
70       Most properties are supported, with the remainder planned for 5.32.
71       Details are in "Wildcards in Property Values" in perlunicode.
72
73   qr'\N{name}' is now supported
74       Previously it was an error to evaluate a named character "\N{...}"
75       within a single quoted regular expression pattern (whose evaluation is
76       deferred from the normal place).  This restriction is now removed.
77
78   Turkic UTF-8 locales are now seamlessly supported
79       Turkic languages have different casing rules than other languages for
80       the characters "i" and "I".  The uppercase of "i" is LATIN CAPITAL
81       LETTER I WITH DOT ABOVE (U+0130); and the lowercase of "I" is LATIN
82       SMALL LETTER DOTLESS I (U+0131).  Unicode furnishes alternate casing
83       rules for use with Turkic languages.  Previously, Perl ignored these,
84       but now, it uses them when it detects that it is operating under a
85       Turkic UTF-8 locale.
86
87   It is now possible to compile perl to always use thread-safe locale
88       operations.
89       Previously, these calls were only used when the perl was compiled to be
90       multi-threaded.  To always enable them, add
91
92        -Accflags='-DUSE_THREAD_SAFE_LOCALE'
93
94       to your Configure flags.
95
96   Eliminate opASSIGN macro usage from core
97       This macro is still defined but no longer used in core
98
99   "-Drv" now means something on "-DDEBUGGING" builds
100       Now, adding the verbose flag ("-Dv") to the "-Dr" flag turns on all
101       possible regular expression debugging.
102

Incompatible Changes

104   Assigning non-zero to $[ is fatal
105       Setting $[ to a non-zero value has been deprecated since Perl 5.12 and
106       now throws a fatal error.  See "Assigning non-zero to $[ is fatal" in
107       perldeprecation.
108
109   Delimiters must now be graphemes
110       See "Use of unassigned code point or non-standalone grapheme for a
111       delimiter." in perldeprecation
112
113   Some formerly deprecated uses of an unescaped left brace "{" in regular
114       expression patterns are now illegal
115       But to avoid breaking code unnecessarily, most instances that issued a
116       deprecation warning, remain legal and now have a non-deprecation
117       warning raised.  See "Unescaped left braces in regular expressions" in
118       perldeprecation.
119
120   Previously deprecated sysread()/syswrite() on :utf8 handles is now fatal
121       Calling sysread(), syswrite(), send() or recv() on a ":utf8" handle,
122       whether applied explicitly or implicitly, is now fatal.  This was
123       deprecated in perl 5.24.
124
125       There were two problems with calling these functions on ":utf8"
126       handles:
127
128       •   All four functions only paid attention to the ":utf8" flag.  Other
129           layers were completely ignored, so a handle with
130           ":encoding(UTF-16LE)" layer would be treated as UTF-8.  Other
131           layers, such as compression are completely ignored with or without
132           the ":utf8" flag.
133
134sysread() and recv() would read from the handle, skipping any
135           validation by the layers, and do no validation of their own.  This
136           could lead to invalidly encoded perl scalars.
137
138       [GH #14839] <https://github.com/Perl/perl5/issues/14839>.
139
140   my() in false conditional prohibited
141       Declarations such as "my $x if 0" are no longer permitted.
142
143       [GH #16702] <https://github.com/Perl/perl5/issues/16702>.
144
145   Fatalize $* and $#
146       These special variables, long deprecated, now throw exceptions when
147       used.
148
149       [GH #16718] <https://github.com/Perl/perl5/issues/16718>.
150
151   Fatalize unqualified use of dump()
152       The "dump()" function, long discouraged, may no longer be used unless
153       it is fully qualified, i.e., "CORE::dump()".
154
155       [GH #16719] <https://github.com/Perl/perl5/issues/16719>.
156
157   Remove File::Glob::glob()
158       The "File::Glob::glob()" function, long deprecated, has been removed
159       and now throws an exception which advises use of
160       "File::Glob::bsd_glob()" instead.
161
162       [GH #16721] <https://github.com/Perl/perl5/issues/16721>.
163
164   "pack()" no longer can return malformed UTF-8
165       It croaks if it would otherwise return a UTF-8 string that contains
166       malformed UTF-8.  This protects against potential security threats.
167       This is considered a bug fix as well.  [GH #16035]
168       <https://github.com/Perl/perl5/issues/16035>.
169
170   Any set of digits in the Common script are legal in a script run of another
171       script
172       There are several sets of digits in the Common script.  "[0-9]" is the
173       most familiar.  But there are also "[\x{FF10}-\x{FF19}]" (FULLWIDTH
174       DIGIT ZERO - FULLWIDTH DIGIT NINE), and several sets for use in
175       mathematical notation, such as the MATHEMATICAL DOUBLE-STRUCK DIGITs.
176       Any of these sets should be able to appear in script runs of, say,
177       Greek.  But the design of 5.30 overlooked all but the ASCII digits
178       "[0-9]", so the design was flawed.  This has been fixed, so is both a
179       bug fix and an incompatibility.  [GH #16704]
180       <https://github.com/Perl/perl5/issues/16704>.
181
182       All digits in a run still have to come from the same set of ten digits.
183
184   JSON::PP enables allow_nonref by default
185       As JSON::XS 4.0 changed its policy and enabled allow_nonref by default,
186       JSON::PP also enabled allow_nonref by default.
187

Deprecations

189   In XS code, use of various macros dealing with UTF-8.
190       This deprecation was scheduled to become fatal in 5.30, but has been
191       delayed to 5.32 due to problems that showed up with some CPAN modules.
192       For details of what's affected, see perldeprecation.
193

Performance Enhancements

195       •   Translating from UTF-8 into the code point it represents now is
196           done via a deterministic finite automaton, speeding it up.  As a
197           typical example, "ord("\x7fff")" now requires 12% fewer
198           instructions than before.  The performance of checking that a
199           sequence of bytes is valid UTF-8 is similarly improved, again by
200           using a DFA.
201
202       •   Eliminate recursion from finalize_op().  [GH #11866]
203           <https://github.com/Perl/perl5/issues/11866>.
204
205       •   A handful of small optimizations related to character folding and
206           character classes in regular expressions.
207
208       •   Optimization of "IV" to "UV" conversions.  [GH #16761]
209           <https://github.com/Perl/perl5/issues/16761>.
210
211       •   Speed up of the integer stringification algorithm by processing two
212           digits at a time instead of one.  [GH #16769]
213           <https://github.com/Perl/perl5/issues/16769>.
214
215       •   Improvements based on LGTM analysis and recommendation.
216           (<https://lgtm.com/projects/g/Perl/perl5/alerts/?mode=tree>).  [GH
217           #16765] <https://github.com/Perl/perl5/issues/16765>.  [GH #16773]
218           <https://github.com/Perl/perl5/issues/16773>.
219
220       •   Code optimizations in regcomp.c, regcomp.h, regexec.c.
221
222       •   Regular expression pattern matching of things like "qr/[^a]/" is
223           significantly sped up, where a is any ASCII character.  Other
224           classes can get this speed up, but which ones is complicated and
225           depends on the underlying bit patterns of those characters, so
226           differs between ASCII and EBCDIC platforms, but all case pairs,
227           like "qr/[Gg]/" are included, as is "[^01]".
228

Modules and Pragmata

230   Updated Modules and Pragmata
231       •   Archive::Tar has been upgraded from version 2.30 to 2.32.
232
233       •   B has been upgraded from version 1.74 to 1.76.
234
235       •   B::Concise has been upgraded from version 1.003 to 1.004.
236
237       •   B::Deparse has been upgraded from version 1.48 to 1.49.
238
239       •   bignum has been upgraded from version 0.49 to 0.51.
240
241       •   bytes has been upgraded from version 1.06 to 1.07.
242
243       •   Carp has been upgraded from version 1.38 to 1.50
244
245       •   Compress::Raw::Bzip2 has been upgraded from version 2.074 to 2.084.
246
247       •   Compress::Raw::Zlib has been upgraded from version 2.076 to 2.084.
248
249       •   Config::Extensions has been upgraded from version 0.02 to 0.03.
250
251       •   Config::Perl::V. has been upgraded from version 0.29 to 0.32. This
252           was due to a new configuration variable that has influence on
253           binary compatibility: "USE_THREAD_SAFE_LOCALE".
254
255       •   CPAN has been upgraded from version 2.20 to 2.22.
256
257       •   Data::Dumper has been upgraded from version 2.170 to 2.174
258
259           Data::Dumper now avoids leaking when "croak"ing.
260
261       •   DB_File has been upgraded from version 1.840 to 1.843.
262
263       •   deprecate has been upgraded from version 0.03 to 0.04.
264
265       •   Devel::Peek has been upgraded from version 1.27 to 1.28.
266
267       •   Devel::PPPort has been upgraded from version 3.40 to 3.52.
268
269       •   Digest::SHA has been upgraded from version 6.01 to 6.02.
270
271       •   Encode has been upgraded from version 2.97 to 3.01.
272
273       •   Errno has been upgraded from version 1.29 to 1.30.
274
275       •   experimental has been upgraded from version 0.019 to 0.020.
276
277       •   ExtUtils::CBuilder has been upgraded from version 0.280230 to
278           0.280231.
279
280       •   ExtUtils::Manifest has been upgraded from version 1.70 to 1.72.
281
282       •   ExtUtils::Miniperl has been upgraded from version 1.08 to 1.09.
283
284       •   ExtUtils::ParseXS has been upgraded from version 3.39 to 3.40.
285           "OUTLIST" parameters are no longer incorrectly included in the
286           automatically generated function prototype.  [GH #16746]
287           <https://github.com/Perl/perl5/issues/16746>.
288
289       •   feature has been upgraded from version 1.52 to 1.54.
290
291       •   File::Copy has been upgraded from version 2.33 to 2.34.
292
293       •   File::Find has been upgraded from version 1.34 to 1.36.
294
295           $File::Find::dont_use_nlink now defaults to 1 on all platforms.
296           [GH #16759] <https://github.com/Perl/perl5/issues/16759>.
297
298           Variables $Is_Win32 and $Is_VMS are being initialized.
299
300       •   File::Glob has been upgraded from version 1.31 to 1.32.
301
302       •   File::Path has been upgraded from version 2.15 to 2.16.
303
304       •   File::Spec has been upgraded from version 3.74 to 3.78.
305
306           Silence Cwd warning on Android builds if "targetsh" is not defined.
307
308       •   File::Temp has been upgraded from version 0.2304 to 0.2309.
309
310       •   Filter::Util::Call has been upgraded from version 1.58 to 1.59.
311
312       •   GDBM_File has been upgraded from version 1.17 to 1.18.
313
314       •   HTTP::Tiny has been upgraded from version 0.070 to 0.076.
315
316       •   I18N::Langinfo has been upgraded from version 0.17 to 0.18.
317
318       •   IO has been upgraded from version 1.39 to 1.40.
319
320       •   IO-Compress has been upgraded from version 2.074 to 2.084.
321
322           Adds support for "IO::Uncompress::Zstd" and
323           "IO::Uncompress::UnLzip".
324
325           The "BinModeIn" and "BinModeOut" options are now no-ops.  ALL files
326           will be read/written in binmode.
327
328       •   IPC::Cmd has been upgraded from version 1.00 to 1.02.
329
330       •   JSON::PP has been upgraded from version 2.97001 to 4.02.
331
332           JSON::PP as JSON::XS 4.0 enables "allow_nonref" by default.
333
334       •   lib has been upgraded from version 0.64 to 0.65.
335
336       •   Locale::Codes has been upgraded from version 3.56 to 3.57.
337
338       •   Math::BigInt has been upgraded from version 1.999811 to 1.999816.
339
340           "bnok()" now supports the full Kronenburg extension.  [cpan #95628]
341           <https://rt.cpan.org/Ticket/Display.html?id=95628>.
342
343       •   Math::BigInt::FastCalc has been upgraded from version 0.5006 to
344           0.5008.
345
346       •   Math::BigRat has been upgraded from version 0.2613 to 0.2614.
347
348       •   Module::CoreList has been upgraded from version 5.20180622 to
349           5.20190520.
350
351           Changes to B::Op_private and Config
352
353       •   Module::Load has been upgraded from version 0.32 to 0.34.
354
355       •   Module::Metadata has been upgraded from version 1.000033 to
356           1.000036.
357
358           Properly clean up temporary directories after testing.
359
360       •   NDBM_File has been upgraded from version 1.14 to 1.15.
361
362       •   Net::Ping has been upgraded from version 2.62 to 2.71.
363
364       •   ODBM_File has been upgraded from version 1.15 to 1.16.
365
366       •   PathTools has been upgraded from version 3.74 to 3.78.
367
368       •   parent has been upgraded from version 0.236 to 0.237.
369
370       •   perl5db.pl has been upgraded from version 1.54 to 1.55.
371
372           Debugging threaded code no longer deadlocks in "DB::sub" nor
373           "DB::lsub".
374
375       •   perlfaq has been upgraded from version 5.021011 to 5.20190126.
376
377       •   PerlIO::encoding has been upgraded from version 0.26 to 0.27.
378
379           Warnings enabled by setting the "WARN_ON_ERR" flag in
380           $PerlIO::encoding::fallback are now only produced if warnings are
381           enabled with "use warnings "utf8";" or setting $^W.
382
383       •   PerlIO::scalar has been upgraded from version 0.29 to 0.30.
384
385       •   podlators has been upgraded from version 4.10 to 4.11.
386
387       •   POSIX has been upgraded from version 1.84 to 1.88.
388
389       •   re has been upgraded from version 0.36 to 0.37.
390
391       •   SDBM_File has been upgraded from version 1.14 to 1.15.
392
393       •   sigtrap has been upgraded from version 1.08 to 1.09.
394
395       •   Storable has been upgraded from version 3.08 to 3.15.
396
397           Storable no longer probes for recursion limits at build time.  [GH
398           #16780] <https://github.com/Perl/perl5/issues/16780> and others.
399
400           Metasploit exploit code was included to test for CVE-2015-1992
401           detection, this caused anti-virus detections on at least one AV
402           suite.  The exploit code has been removed and replaced with a
403           simple functional test.  [GH #16778]
404           <https://github.com/Perl/perl5/issues/16778>
405
406       •   Test::Simple has been upgraded from version 1.302133 to 1.302162.
407
408       •   Thread::Queue has been upgraded from version 3.12 to 3.13.
409
410       •   threads::shared has been upgraded from version 1.58 to 1.60.
411
412           Added support for extra tracing of locking, this requires a
413           "-DDEBUGGING" and extra compilation flags.
414
415       •   Time::HiRes has been upgraded from version 1.9759 to 1.9760.
416
417       •   Time::Local has been upgraded from version 1.25 to 1.28.
418
419       •   Time::Piece has been upgraded from version 1.3204 to 1.33.
420
421       •   Unicode::Collate has been upgraded from version 1.25 to 1.27.
422
423       •   Unicode::UCD has been upgraded from version 0.70 to 0.72.
424
425       •   User::grent has been upgraded from version 1.02 to 1.03.
426
427       •   utf8 has been upgraded from version 1.21 to 1.22.
428
429       •   vars has been upgraded from version 1.04 to 1.05.
430
431           "vars.pm" no longer disables non-vars strict when checking if
432           strict vars is enabled.  [GH #15851]
433           <https://github.com/Perl/perl5/issues/15851>.
434
435       •   version has been upgraded from version 0.9923 to 0.9924.
436
437       •   warnings has been upgraded from version 1.42 to 1.44.
438
439       •   XS::APItest has been upgraded from version 0.98 to 1.00.
440
441       •   XS::Typemap has been upgraded from version 0.16 to 0.17.
442
443   Removed Modules and Pragmata
444       The following modules will be removed from the core distribution in a
445       future release, and will at that time need to be installed from CPAN.
446       Distributions on CPAN which require these modules will need to list
447       them as prerequisites.
448
449       The core versions of these modules will now issue "deprecated"-category
450       warnings to alert you to this fact.  To silence these deprecation
451       warnings, install the modules in question from CPAN.
452
453       Note that these are (with rare exceptions) fine modules that you are
454       encouraged to continue to use.  Their disinclusion from core primarily
455       hinges on their necessity to bootstrapping a fully functional, CPAN-
456       capable Perl installation, not usually on concerns over their design.
457
458       •   B::Debug is no longer distributed with the core distribution.  It
459           continues to be available on CPAN as "B::Debug
460           <https://metacpan.org/pod/B::Debug>".
461
462       •   Locale::Codes has been removed at the request of its author.  It
463           continues to be available on CPAN as "Locale::Codes
464           <https://metacpan.org/pod/Locale::Codes>" [GH #16660]
465           <https://github.com/Perl/perl5/issues/16660>.
466

Documentation

468   Changes to Existing Documentation
469       We have attempted to update the documentation to reflect the changes
470       listed in this document.  If you find any we have missed, send email to
471       perlbug@perl.org <mailto:perlbug@perl.org>.
472
473       perlapi
474
475       •   "AvFILL()" was wrongly listed as deprecated.  This has been
476           corrected.  [GH #16586]
477           <https://github.com/Perl/perl5/issues/16586>
478
479       perlop
480
481       •   We no longer have null (empty line) here doc terminators, so perlop
482           should not refer to them.
483
484       •   The behaviour of "tr" when the delimiter is an apostrophe has been
485           clarified.  In particular, hyphens aren't special, and "\x{}" isn't
486           interpolated.  [GH #15853]
487           <https://github.com/Perl/perl5/issues/15853>
488
489       perlreapi, perlvar
490
491       •   Improve docs for lastparen, lastcloseparen.
492
493       perlfunc
494
495       •   The entry for "-X" in perlfunc has been clarified to indicate that
496           symbolic links are followed for most tests.
497
498       •   Clarification of behaviour of "reset EXPR".
499
500       •   Try to clarify that "ref(qr/xx/)" returns "Regexp" rather than
501           "REGEXP" and why.  [GH #16801]
502           <https://github.com/Perl/perl5/issues/16801>.
503
504       perlreref
505
506       •   Clarification of the syntax of /(?(cond)yes)/.
507
508       perllocale
509
510       •   There are actually two slightly different types of UTF-8 locales:
511           one for Turkic languages and one for everything else. Starting in
512           Perl v5.30, Perl seamlessly handles both types.
513
514       perlrecharclass
515
516       •   Added a note for the ::xdigit:: character class.
517
518       perlvar
519
520       •   More specific documentation of paragraph mode.  [GH #16787]
521           <https://github.com/Perl/perl5/issues/16787>.
522

Diagnostics

524       The following additions or changes have been made to diagnostic output,
525       including warnings and fatal error messages.  For the complete list of
526       diagnostic messages, see perldiag.
527
528   Changes to Existing Diagnostics
529       •   As noted under "Incompatible Changes" above, the deprecation
530           warning "Unescaped left brace in regex is deprecated here (and will
531           be fatal in Perl 5.30), passed through in regex; marked by <-- HERE
532           in m/%s/" has been changed to the non-deprecation warning
533           "Unescaped left brace in regex is passed through in regex; marked
534           by <-- HERE in m/%s/".
535
536       •   Specifying "\o{}" without anything between the braces now yields
537           the fatal error message "Empty \o{}".  Previously it was  "Number
538           with no digits".  This means the same wording is used for this kind
539           of error as with similar constructs such as "\p{}".
540
541       •   Within the scope of the experimental feature "use re 'strict'",
542           specifying "\x{}" without anything between the braces now yields
543           the fatal error message "Empty \x{}".  Previously it was  "Number
544           with no digits".  This means the same wording is used for this kind
545           of error as with similar constructs such as "\p{}".  It is legal,
546           though not wise to have an empty "\x" outside of "re 'strict'"; it
547           silently generates a NUL character.
548
549       •   Type of arg %d to %s must be %s (not %s)
550
551           Attempts to push, pop, etc on a hash or glob now produce this
552           message rather than complaining that they no longer work on
553           scalars.  [GH #15774] <https://github.com/Perl/perl5/issues/15774>.
554
555       •   Prototype not terminated
556
557           The file and line number is now reported for this error.  [GH
558           #16697] <https://github.com/Perl/perl5/issues/16697>
559
560       •   Under "-Dr" (or "use re 'Debug'") the compiled regex engine program
561           is displayed. It used to use two different spellings for infinity,
562           "INFINITY", and "INFTY". It now uses the latter exclusively, as
563           that spelling has been around the longest.
564

Utility Changes

566   xsubpp
567       •   The generated prototype (with "PROTOTYPES: ENABLE") would include
568           "OUTLIST" parameters, but these aren't arguments to the perl
569           function.  This has been rectified.  [GH #16746]
570           <https://github.com/Perl/perl5/issues/16746>.
571

Configuration and Compilation

573       •   Normally the thread-safe locale functions are used only on threaded
574           builds.  It is now possible to force their use on unthreaded builds
575           on systems that have them available, by including the
576           "-Accflags='-DUSE_THREAD_SAFE_LOCALE'" option to Configure.
577
578       •   Improve detection of memrchr, strlcat, and strlcpy
579
580       •   Improve Configure detection of memmem().  [GH #16807]
581           <https://github.com/Perl/perl5/issues/16807>.
582
583       •   Multiple improvements and fixes for -DPERL_GLOBAL_STRUCT build
584           option.
585
586       •   Fix -DPERL_GLOBAL_STRUCT_PRIVATE build option.
587

Testing

589t/lib/croak/op [GH #15774]
590           <https://github.com/Perl/perl5/issues/15774>.
591
592           separate error for "push", etc. on hash/glob.
593
594t/op/svleak.t [GH #16749]
595           <https://github.com/Perl/perl5/issues/16749>.
596
597           Add test for "goto &sub" in overload leaking.
598
599       •   Split t/re/fold_grind.t into multiple test files.
600
601       •   Fix intermittent tests which failed due to race conditions which
602           surface during parallel testing.  [GH #16795]
603           <https://github.com/Perl/perl5/issues/16795>.
604
605       •   Thoroughly test paragraph mode, using a new test file,
606           t/io/paragraph_mode.t.  [GH #16787]
607           <https://github.com/Perl/perl5/issues/16787>.
608
609       •   Some tests in t/io/eintr.t caused the process to hang on pre-16
610           Darwin. These tests are skipped for those version of Darwin.
611

Platform Support

613   Platform-Specific Notes
614       HP-UX 11.11
615           An obscure problem in "pack()" when compiling with HP C-ANSI-C has
616           been fixed by disabling optimizations in pp_pack.c.
617
618       Mac OS X
619           Perl's build and testing process on Mac OS X for "-Duseshrplib"
620           builds is now compatible with Mac OS X System Integrity Protection
621           (SIP).
622
623           SIP prevents binaries in /bin (and a few other places) being passed
624           the "DYLD_LIBRARY_PATH" environment variable.  For our purposes
625           this prevents "DYLD_LIBRARY_PATH" from being passed to the shell,
626           which prevents that variable being passed to the testing or build
627           process, so running "perl" couldn't find libperl.dylib.
628
629           To work around that, the initial build of the perl executable
630           expects to find libperl.dylib in the build directory, and the
631           library path is then adjusted during installation to point to the
632           installed library.
633
634           [GH #15057] <https://github.com/Perl/perl5/issues/15057>.
635
636       Minix3
637           Some support for Minix3 has been re-added.
638
639       Cygwin
640           Cygwin doesn't make "cuserid" visible.
641
642       Win32 Mingw
643           C99 math functions are now available.
644
645       Windows
646           •   The "USE_CPLUSPLUS" build option which has long been available
647               in win32/Makefile (for nmake) and win32/makefile.mk (for dmake)
648               is now also available in win32/GNUmakefile (for gmake).
649
650           •   The nmake makefile no longer defaults to Visual C++ 6.0 (a very
651               old version which is unlikely to be widely used today).  As a
652               result, it is now a requirement to specify the "CCTYPE" since
653               there is no obvious choice of which modern version to default
654               to instead.  Failure to specify "CCTYPE" will result in an
655               error being output and the build will stop.
656
657               (The dmake and gmake makefiles will automatically detect which
658               compiler is being used, so do not require "CCTYPE" to be set.
659               This feature has not yet been added to the nmake makefile.)
660
661           •   "sleep()" with warnings enabled for a "USE_IMP_SYS" build no
662               longer warns about the sleep timeout being too large.  [GH
663               #16631] <https://github.com/Perl/perl5/issues/16631>.
664
665           •   Support for compiling perl on Windows using Microsoft Visual
666               Studio 2019 (containing Visual C++ 14.2) has been added.
667
668socket() now sets $! if the protocol, address family and socket
669               type combination is not found.  [GH #16849]
670               <https://github.com/Perl/perl5/issues/16849>.
671
672           •   The Windows Server 2003 SP1 Platform SDK build, with its early
673               x64 compiler and tools, was accidentally broken in Perl 5.27.9.
674               This has now been fixed.
675

Internal Changes

677       •   The sizing pass has been eliminated from the regular expression
678           compiler.  An extra pass may instead be needed in some cases to
679           count the number of parenthetical capture groups.
680
681       •   A new function ""my_strtod"" in perlapi or its synonym, Strtod(),
682           is now available with the same signature as the libc strtod().  It
683           provides strotod() equivalent behavior on all platforms, using the
684           best available precision, depending on platform capabilities and
685           Configure options, while handling locale-related issues, such as if
686           the radix character should be a dot or comma.
687
688       •   Added "newSVsv_nomg()" to copy a SV without processing get magic on
689           the source.  [GH #16461]
690           <https://github.com/Perl/perl5/issues/16461>.
691
692       •   It is now forbidden to malloc more than "PTRDIFF_T_MAX" bytes.
693           Much code (including C optimizers) assumes that all data structures
694           will not be larger than this, so this catches such attempts before
695           overflow happens.
696
697       •   Two new regnodes have been introduced "EXACT_ONLY8", and
698           "EXACTFU_ONLY8". They're equivalent to "EXACT" and "EXACTFU",
699           except that they contain a code point which requires UTF-8 to
700           represent/match. Hence, if the target string isn't UTF-8, we know
701           it can't possibly match, without needing to try.
702
703       •   "print_bytes_for_locale()" is now defined if "DEBUGGING", Prior, it
704           didn't get defined unless "LC_COLLATE" was defined on the platform.
705

Selected Bug Fixes

707       •   Compilation under "-DPERL_MEM_LOG" and "-DNO_LOCALE" have been
708           fixed.
709
710       •   Perl 5.28 introduced an "index()" optimization when comparing to -1
711           (or indirectly, e.g. >= 0).  When this optimization was triggered
712           inside a "when" clause it caused a warning ("Argument %s isn't
713           numeric in smart match").  This has now been fixed.  [GH #16626]
714           <https://github.com/Perl/perl5/issues/16626>
715
716       •   The new in-place editing code no longer leaks directory handles.
717           [GH #16602] <https://github.com/Perl/perl5/issues/16602>.
718
719       •   Warnings produced from constant folding operations on overloaded
720           values no longer produce spurious "Use of uninitialized value"
721           warnings.  [GH #16349]
722           <https://github.com/Perl/perl5/issues/16349>.
723
724       •   Fix for "mutator not seen in (lex = ...) .= ..."  [GH #16655]
725           <https://github.com/Perl/perl5/issues/16655>.
726
727       •   "pack "u", "invalid uuencoding"" now properly NUL terminates the
728           zero-length SV produced.  [GH #16343]
729           <https://github.com/Perl/perl5/issues/16343>.
730
731       •   Improve the debugging output for calloc() calls with "-Dm".  [GH
732           #16653] <https://github.com/Perl/perl5/issues/16653>.
733
734       •   Regexp script runs were failing to permit ASCII digits in some
735           cases.  [GH #16704] <https://github.com/Perl/perl5/issues/16704>.
736
737       •   On Unix-like systems supporting a platform-specific technique for
738           determining $^X, Perl failed to fall back to the generic technique
739           when the platform-specific one fails (for example, a Linux system
740           with /proc not mounted).  This was a regression in Perl 5.28.0.
741           [GH #16715] <https://github.com/Perl/perl5/issues/16715>.
742
743       •   SDBM_File is now more robust with corrupt database files.  The
744           improvements do not make SDBM files suitable as an interchange
745           format.  [GH #16164] <https://github.com/Perl/perl5/issues/16164>.
746
747       •   "binmode($fh);" or "binmode($fh, ':raw');" now properly removes the
748           ":utf8" flag from the default ":crlf" I/O layer on Win32.  [GH
749           #16730] <https://github.com/Perl/perl5/issues/16730>.
750
751       •   The experimental reference aliasing feature was misinterpreting
752           array and hash slice assignment as being localised, e.g.
753
754               \(@a[3,5,7]) = \(....);
755
756           was being interpreted as:
757
758               local \(@a[3,5,7]) = \(....);
759
760           [GH #16701] <https://github.com/Perl/perl5/issues/16701>.
761
762       •   "sort SUBNAME" within an "eval EXPR" when "EXPR" was UTF-8 upgraded
763           could panic if the "SUBNAME" was non-ASCII.  [GH #16979]
764           <https://github.com/Perl/perl5/issues/16979>.
765
766       •   Correctly handle realloc() modifying "errno" on success so that the
767           modification isn't visible to the perl user, since realloc() is
768           called implicitly by the interpreter.  This modification is
769           permitted by the C standard, but has only been observed on FreeBSD
770           13.0-CURRENT.  [GH #16907]
771           <https://github.com/Perl/perl5/issues/16907>.
772
773       •   Perl now exposes POSIX "getcwd" as "Internals::getcwd()" if
774           available.  This is intended for use by "Cwd.pm" during
775           bootstrapping and may be removed or changed without notice.  This
776           fixes some bootstrapping issues while building perl in a directory
777           where some ancestor directory isn't readable.  [GH #16903]
778           <https://github.com/Perl/perl5/issues/16903>.
779
780       •   "pack()" no longer can return malformed UTF-8.  It croaks if it
781           would otherwise return a UTF-8 string that contains malformed
782           UTF-8.  This protects against potential security threats.  [GH
783           #16035] <https://github.com/Perl/perl5/issues/16035>.
784
785       •   See "Any set of digits in the Common script are legal in a script
786           run of another script".
787
788       •   Regular expression matching no longer leaves stale UTF-8 length
789           magic when updating $^R. This could result in "length($^R)"
790           returning an incorrect value.
791
792       •   Reduce recursion on ops [GH #11866]
793           <https://github.com/Perl/perl5/issues/11866>.
794
795           This can prevent stack overflow when processing extremely deep op
796           trees.
797
798       •   Avoid leak in multiconcat with overloading.  [GH #16823]
799           <https://github.com/Perl/perl5/issues/16823>.
800
801       •   The handling of user-defined "\p{}" properties (see "User-Defined
802           Character Properties" in perlunicode) has been rewritten to be in C
803           (instead of Perl).  This speeds things up, but in the process
804           several inconsistencies and bug fixes are made.
805
806           1.  A few error messages have minor wording changes.  This is
807               essentially because the new way is integrated into the regex
808               error handling mechanism that marks the position in the input
809               at which the error occurred.  That was not possible previously.
810               The messages now also contain additional back-trace-like
811               information in case the error occurs deep in nested calls.
812
813           2.  A user-defined property is implemented as a perl subroutine
814               with certain highly constrained naming conventions.  It was
815               documented previously that the sub would be in the current
816               package if the package was unspecified.  This turned out not to
817               be true in all cases, but now it is.
818
819           3.  All recursive calls are treated as infinite recursion.
820               Previously they would cause the interpreter to panic.  Now,
821               they cause the regex pattern to fail to compile.
822
823           4.  Similarly, any other error likely would lead to a panic; now to
824               just the pattern failing to compile.
825
826           5.  The old mechanism did not detect illegal ranges in the
827               definition of the property.  Now, the range max must not be
828               smaller than the range min.  Otherwise, the pattern fails to
829               compile.
830
831           6.  The intention was to have each sub called only once during the
832               lifetime of the program, so that a property's definition is
833               immutable.  This was relaxed so that it could be called once
834               for all /i compilations, and potentially a second time for
835               non-/i (the sub is passed a parameter indicating which).
836               However, in practice there were instances when this was broken,
837               and multiple calls were possible.  Those have been fixed.  Now
838               (besides the /i,non-/i cases) the only way a sub can be called
839               multiple times is if some component of it has not been defined
840               yet.  For example, suppose we have sub IsA() whose definition
841               is known at compile time, and it in turn calls isB() whose
842               definition is not yet known.  isA() will be called each time a
843               pattern it appears in is compiled.  If isA() also calls isC()
844               and that definition is known, isC() will be called just once.
845
846           7.  There were some races and very long hangs should one thread be
847               compiling the same property as another simultaneously.  These
848               have now been fixed.
849
850       •   Fixed a failure to match properly.
851
852           An EXACTFish regnode has a finite length it can hold for the string
853           being matched.  If that length is exceeded, a second node is used
854           for the next segment of the string, for as many regnodes as are
855           needed.  Care has to be taken where to break the string, in order
856           to deal multi-character folds in Unicode correctly. If we want to
857           break a string at a place which could potentially be in the middle
858           of a multi-character fold, we back off one (or more) characters,
859           leaving a shorter EXACTFish regnode. This backing off mechanism
860           contained an off-by-one error.  [GH #16806]
861           <https://github.com/Perl/perl5/issues/16806>.
862
863       •   A bare "eof" call with no previous file handle now returns true.
864           [GH #16786] <https://github.com/Perl/perl5/issues/16786>
865
866       •   Failing to compile a format now aborts compilation.  Like other
867           errors in sub-parses this could leave the parser in a strange
868           state, possibly crashing perl if compilation continued.  [GH
869           #16169] <https://github.com/Perl/perl5/issues/16169>
870
871       •   If an in-place edit is still in progress during global destruction
872           and the process exit code (as stored in $?) is zero, perl will now
873           treat the in-place edit as successful, replacing the input file
874           with any output produced.
875
876           This allows code like:
877
878             perl -i -ne 'print "Foo"; last'
879
880           to replace the input file, while code like:
881
882             perl -i -ne 'print "Foo"; die'
883
884           will not.  Partly resolves [GH #16748]
885           <https://github.com/Perl/perl5/issues/16748>.
886
887       •   A regression in 5.28 caused the following code to fail
888
889            close(STDIN); open(CHILD, "|wc -l")'
890
891           because the child's stdin would be closed on exec. This has now
892           been fixed.
893
894       •   Fixed an issue where compiling a regexp containing both compile-
895           time and run-time code blocks could lead to trying to compile
896           something which is invalid syntax.
897
898       •   Fixed build failures with "-DNO_LOCALE_NUMERIC" and
899           "-DNO_LOCALE_COLLATE".  [GH #16771]
900           <https://github.com/Perl/perl5/issues/16771>.
901
902       •   Prevent the tests in ext/B/t/strict.t from being skipped.  [GH
903           #16783] <https://github.com/Perl/perl5/issues/16783>.
904
905       •   "/di" nodes ending or beginning in s are now "EXACTF". We do not
906           want two "EXACTFU" to be joined together during optimization, and
907           to form a "ss", "sS", "Ss" or "SS" sequence; they are the only
908           multi-character sequences which may match differently under "/ui"
909           and "/di".
910

Acknowledgements

912       Perl 5.30.0 represents approximately 11 months of development since
913       Perl 5.28.0 and contains approximately 620,000 lines of changes across
914       1,300 files from 58 authors.
915
916       Excluding auto-generated files, documentation and release tools, there
917       were approximately 510,000 lines of changes to 750 .pm, .t, .c and .h
918       files.
919
920       Perl continues to flourish into its fourth decade thanks to a vibrant
921       community of users and developers. The following people are known to
922       have contributed the improvements that became Perl 5.30.0:
923
924       Aaron Crane, Abigail, Alberto Simo~es, Alexandr Savca, Andreas Koenig,
925       Andy Dougherty, Aristotle Pagaltzis, Brian Greenfield, Chad Granum,
926       Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsaaker, Dan
927       Book, Dan Dedrick, Daniel Dragan, Dan Kogai, David Cantrell, David
928       Mitchell, Dominic Hargreaves, E. Choroba, Ed J, Eugen Konkov, Francois
929       Perrad, Graham Knop, Hauke D, H.Merijn Brand, Hugo van der Sanden,
930       Jakub Wilk, James Clarke, James E Keenan, Jerry D. Hedden, Jim Cromie,
931       John SJ Anderson, Karen Etheridge, Karl Williamson, Leon Timmermans,
932       Matthias Bethke, Nicholas Clark, Nicolas R., Niko Tyni, Pali, Petr
933       PisaX, Phil Pearl (Lobbes), Richard Leach, Ryan Voots, Sawyer X, Shlomi
934       Fish, Sisyphus, Slaven Rezic, Steve Hay, Sullivan Beck, Tina Mueller,
935       Tomasz Konojacki, Tom Wyant, Tony Cook, Unicode Consortium, Yves Orton,
936       Zak B. Elep.
937
938       The list above is almost certainly incomplete as it is automatically
939       generated from version control history. In particular, it does not
940       include the names of most of the (very much appreciated) contributors
941       who reported issues to the Perl bug tracker. Noteworthy in this release
942       were the large number of bug fixes made possible by Sergey Aleynikov's
943       high quality perlbug reports for issues he discovered by fuzzing with
944       AFL.
945
946       Many of the changes included in this version originated in the CPAN
947       modules included in Perl's core. We're grateful to the entire CPAN
948       community for helping Perl to flourish.
949
950       For a more complete list of all of Perl's historical contributors,
951       please see the AUTHORS file in the Perl source distribution.
952

Reporting Bugs

954       If you find what you think is a bug, you might check the perl bug
955       database at <https://rt.perl.org/>.  There may also be information at
956       <http://www.perl.org/>, the Perl Home Page.
957
958       If you believe you have an unreported bug, please run the perlbug
959       program included with your release.  Be sure to trim your bug down to a
960       tiny but sufficient test case.  Your bug report, along with the output
961       of "perl -V", will be sent off to perlbug@perl.org to be analysed by
962       the Perl porting team.
963
964       If the bug you are reporting has security implications which make it
965       inappropriate to send to a publicly archived mailing list, then see
966       "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of
967       how to report the issue.
968

Give Thanks

970       If you wish to thank the Perl 5 Porters for the work we had done in
971       Perl 5, you can do so by running the "perlthanks" program:
972
973           perlthanks
974
975       This will send an email to the Perl 5 Porters list with your show of
976       thanks.
977

SEE ALSO

979       The Changes file for an explanation of how to view exhaustive details
980       on what changed.
981
982       The INSTALL file for how to build Perl.
983
984       The README file for general stuff.
985
986       The Artistic and Copying files for copyright information.
987
988
989
990perl v5.34.1                      2022-03-15                  PERL5300DELTA(1)
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