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1=encoding utf8
2
3=head1 NAME
4
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5[ this is a template for a new perldelta file. Any text flagged as XXX needs
6to be processed before release. ]
7
8perldelta - what is new for perl v5.21.1
c68523cb 9
238894db 10=head1 DESCRIPTION
c68523cb 11
7065301c 12This document describes differences between the 5.21.0 release and the 5.21.1
238894db 13release.
c68523cb 14
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15If you are upgrading from an earlier release such as 5.20.0, first read
16L<perl5210delta>, which describes differences between 5.20.0 and 5.21.0.
17
18=head1 Notice
19
20XXX Any important notices here
21
22=head1 Core Enhancements
23
24XXX New core language features go here. Summarize user-visible core language
25enhancements. Particularly prominent performance optimisations could go
26here, but most should go in the L</Performance Enhancements> section.
27
28[ List each enhancement as a =head2 entry ]
29
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30=head2 C<qr/foo/x> now ignores any Unicode pattern white space
31
32The C</x> regular expression modifier allows the pattern to contain
33white space and comments, both of which are ignored, for improved
34readability. Until now, not all the white space characters that Unicode
35designates for this purpose were handled. The additional ones now
36recognized are
37U+0085 NEXT LINE,
38U+200E LEFT-TO-RIGHT MARK,
39U+200F RIGHT-TO-LEFT MARK,
40U+2028 LINE SEPARATOR,
41and
42U+2029 PARAGRAPH SEPARATOR.
43
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44=head1 Security
45
46XXX Any security-related notices go here. In particular, any security
47vulnerabilities closed should be noted here rather than in the
48L</Selected Bug Fixes> section.
49
50[ List each security issue as a =head2 entry ]
51
52=head1 Incompatible Changes
53
54XXX For a release on a stable branch, this section aspires to be:
55
56 There are no changes intentionally incompatible with 5.XXX.XXX
57 If any exist, they are bugs, and we request that you submit a
58 report. See L</Reporting Bugs> below.
59
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60=head2 In double-quotish C<\cI<X>>, I<X> must now be a printable ASCII character
61
62In prior releases, failure to do this raised a deprecation warning.
7065301c 63
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64=head2 Splitting the tokens C<(?> and C<(*> in regular expressions is
65now a fatal compilation error.
66
67These had been deprecated since v5.18.
68
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69=head2 5 additional characters are treated as white space under C</x> in
70regex patterns (unless escaped)
71
72The use of these characters with C</x> outside bracketed character
73classes and when not preceeded by a backslash has raised a deprecation
74warning since v5.18. Now they will be ignored. See L</qrE<sol>fooE<sol>x>
75for the list of the five characters.
76
77=head2 Comment lines within S<C<(?[ ])>> now are ended only by a C<\n>
78
79S<C<(?[ ])>> is an experimental feature, introduced in v5.18. It operates
80as if C</x> is always enabled. But there was a difference, comment
81lines (following a C<#> character) were terminated by anything matching
82C<\R> which includes all vertical whitespace, such as form feeds. For
83consistency, this is now changed to match what terminates comment lines
84outside S<C<(?[ ])>>, namely a C<\n> (even if escaped), which is the
85same as what terminates a heredoc string and formats.
86
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87=head2 Omitting % and @ on hash and array names is no longer permitted
88
89Really old Perl let you omit the @ on array names and the % on hash
90names in some spots. This has issued a deprecation warning since Perl
915.0, and is no longer permitted.
92
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93=head1 Deprecations
94
95XXX Any deprecated features, syntax, modules etc. should be listed here.
96
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97=head2 Using a NO-BREAK space in a character alias for C<\N{...}> is now
98deprecated
99
100This non-graphic character is essentially indistinguishable from a
101regular space, and so should not be allowed. See
102L<charnames/CUSTOM ALIASES>.
103
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104=head2 Module removals
105
106XXX Remove this section if inapplicable.
107
108The following modules will be removed from the core distribution in a
109future release, and will at that time need to be installed from CPAN.
110Distributions on CPAN which require these modules will need to list them as
111prerequisites.
112
113The core versions of these modules will now issue C<"deprecated">-category
114warnings to alert you to this fact. To silence these deprecation warnings,
115install the modules in question from CPAN.
116
117Note that these are (with rare exceptions) fine modules that you are encouraged
118to continue to use. Their disinclusion from core primarily hinges on their
119necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
120not usually on concerns over their design.
121
122=over
123
124=item XXX
125
126XXX Note that deprecated modules should be listed here even if they are listed
127as an updated module in the L</Modules and Pragmata> section.
128
129=back
130
131[ List each other deprecation as a =head2 entry ]
132
133=head1 Performance Enhancements
134
135XXX Changes which enhance performance without changing behaviour go here.
136There may well be none in a stable release.
137
138[ List each enhancement as a =item entry ]
139
140=over 4
141
142=item *
143
144XXX
145
146=back
147
7ef8b31d 148=head1 Modules and Pragmata
f6f3144e 149
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150XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
151go here. If Module::CoreList is updated, generate an initial draft of the
152following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
153for important changes should then be added by hand. In an ideal world,
154dual-life modules would have a F<Changes> file that could be cribbed.
155
156[ Within each section, list entries as a =item entry ]
157
158=head2 New Modules and Pragmata
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159
160=over 4
161
162=item *
163
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164XXX
165
166=back
167
168=head2 Updated Modules and Pragmata
169
170=over 4
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171
172=item *
173
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174L<Carp> has been upgraded from version 1.3301 to 1.34.
175
176Carp::Heavy now ignores version mismatches with Carp if Carp is newer
177than 1.12, since Carp::Heavy's guts were merged into Carp at that
178point.
179L<[perl #121574]|https://rt.perl.org/Ticket/Display.html?id=121574>
180
181=item *
182
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183L<Encode> has been upgraded from version 2.60_01 to 2.62.
184
185B<piconv> now has better error handling when the encoding name is nonexistent,
186and a build breakage when upgrading L<Encode> in perl-5.8.2 and earlier has
187been fixed.
188
189=item *
190
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191The libnet collection of modules has been upgraded from version 1.25 to 1.27.
192
193There are only whitespace changes to the installed files.
194
195=item *
196
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197The Locale-Codes collection of modules has been upgraded from vesion 3.30 to 3.31.
198
199Fixed a bug in the scripts used to extract data from spreadsheets that
200prevented the SHP currency code from being found.
201L<[cpan #94229]|https://rt.cpan.org/Ticket/Display.html?id=94229>
202
203=item *
204
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205L<Math::BigInt> has been upgraded from version 1.9993 to 1.9994.
206
207Synchronize POD changes from the CPAN release.
208
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209C<< Math::BigFloat->blog(x) >> would sometimes return blog(2*x) when
210the accuracy was greater than 70 digits.
211
212The result of C<< Math::BigFloat->bdiv() >> in list context now
213satisfies C<< x = quotient * divisor + remainder >>.
214
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215=item *
216
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217L<Math::BigRat> has been upgraded from version 0.2606 to 0.2607.
218
219Synchronize POD changes from the CPAN release.
220
221=item *
222
f97d984b 223L<Module::Metadata> has been upgraded from version 1.000022 to 1.000024.
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224
225Support installations on older perls with an L<ExtUtils::MakeMaker> earlier
226than 6.63_03
227
228=item *
229
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230L<perl5db.pl> has been upgraded from version 1.44 to 1.45.
231
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232=item *
233
234A mismatch between the documentation and the code in utf8::downgrade()
235was fixed in favour of the documentation. The optional second argument
236is now correctly treated as a perl boolean (true/false semantics) and
237not as an integer.
238
239=item *
240
c13fd1a2 241fork() in the debugger under C<tmux> will now create a new window for
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242the forked process. L<[perl
243#121333]|https://rt.perl.org/Ticket/Display.html?id=121333>
244
245The debugger now saves the current working directory on startup and
246restores it when you restart your program with C<R> or <rerun>. L<[perl
247#121509]|https://rt.perl.org/Ticket/Display.html?id=121509>
24a38d90 248
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249L<Unicode::Collate> has been upgraded from version 1.04 to 1.07.
250
251Version 0.67's improved discontiguous contractions is invalidated by default
252and is supported as a parameter 'long_contraction'.
253
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254=item *
255
256L<Unicode::Normalize> has been upgraded from version 1.17 to 1.18.
257
258The XSUB implementation has been removed in favour of pure Perl.
259
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260=item *
261
262L<Hash::Util> has been upgraded from version 0.16 to 0.17.
263
264Minor bug fixes and documentation fixes to Hash::Util::hash_stats()
265
266
238894db 267=back
24a38d90 268
92fa985e 269=head2 Removed Modules and Pragmata
24a38d90 270
238894db 271=over 4
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272
273=item *
274
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275XXX
276
277=back
278
279=head1 Documentation
280
281XXX Changes to files in F<pod/> go here. Consider grouping entries by
282file and be sure to link to the appropriate page, e.g. L<perlfunc>.
283
284=head2 New Documentation
285
286XXX Changes which create B<new> files in F<pod/> go here.
287
288=head3 L<XXX>
289
290XXX Description of the purpose of the new file here
291
292=head2 Changes to Existing Documentation
293
294XXX Changes which significantly change existing files in F<pod/> go here.
295However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
296section.
297
298=head3 L<XXX>
299
300=over 4
301
302=item *
303
304XXX Description of the change here
305
306=back
307
308=head1 Diagnostics
309
310The following additions or changes have been made to diagnostic output,
311including warnings and fatal error messages. For the complete list of
312diagnostic messages, see L<perldiag>.
313
314XXX New or changed warnings emitted by the core's C<C> code go here. Also
315include any changes in L<perldiag> that reconcile it to the C<C> code.
316
317=head2 New Diagnostics
318
319XXX Newly added diagnostic messages go under here, separated into New Errors
320and New Warnings
321
322=head3 New Errors
323
324=over 4
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325
326=item *
327
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328XXX L<message|perldiag/"message">
329
330=back
331
332=head3 New Warnings
333
334=over 4
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335
336=item *
337
7065301c 338XXX L<message|perldiag/"message">
24a38d90 339
238894db 340=back
24a38d90 341
7065301c 342=head2 Changes to Existing Diagnostics
24a38d90 343
7065301c 344XXX Changes (i.e. rewording) of diagnostic messages go here
24a38d90 345
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346=over 4
347
348=item *
349
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350L<Unsuccessful %s on filename containing newline|perldiag/"Unsuccessful %s on filename containing newline">
351
352This warning is now only produced when the newline is at the end of
353the filename.
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354
355=back
356
357=head1 Utility Changes
358
359XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
360Most of these are built within the directories F<utils> and F<x2p>.
361
362[ List utility changes as a =head2 entry for each utility and =item
363entries for each change
364Use L<XXX> with program names to get proper documentation linking. ]
365
366=head2 L<XXX>
367
368=over 4
369
370=item *
24a38d90 371
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372XXX
373
374=back
375
376=head1 Configuration and Compilation
377
378XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
379go here. Any other changes to the Perl build process should be listed here.
380However, any platform-specific changes should be listed in the
381L</Platform Support> section, instead.
382
383[ List changes as a =item entry ].
384
385=over 4
386
387=item *
388
389XXX
390
391=back
392
393=head1 Testing
394
395XXX Any significant changes to the testing of a freshly built perl should be
396listed here. Changes which create B<new> files in F<t/> go here as do any
397large changes to the testing harness (e.g. when parallel testing was added).
398Changes to existing files in F<t/> aren't worth summarizing, although the bugs
399that they represent may be covered elsewhere.
400
401[ List each test improvement as a =item entry ]
402
403=over 4
404
405=item *
406
407XXX
408
409=back
410
411=head1 Platform Support
412
413XXX Any changes to platform support should be listed in the sections below.
414
415[ Within the sections, list each platform as a =item entry with specific
416changes as paragraphs below it. ]
417
418=head2 New Platforms
419
420XXX List any platforms that this version of perl compiles on, that previous
421versions did not. These will either be enabled by new files in the F<hints/>
422directories, or new subdirectories and F<README> files at the top level of the
423source tree.
424
425=over 4
426
427=item XXX-some-platform
428
429XXX
430
431=back
432
433=head2 Discontinued Platforms
434
435XXX List any platforms that this version of perl no longer compiles on.
436
437=over 4
438
439=item XXX-some-platform
440
441XXX
442
443=back
444
445=head2 Platform-Specific Notes
446
447XXX List any changes for specific platforms. This could include configuration
448and compilation changes or changes in portability/compatibility. However,
449changes within modules for platforms should generally be listed in the
450L</Modules and Pragmata> section.
451
452=over 4
453
454=item XXX-some-platform
455
456XXX
457
458=back
459
460=head1 Internal Changes
461
462XXX Changes which affect the interface available to C<XS> code go here. Other
463significant internal changes for future core maintainers should be noted as
464well.
465
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466=over 4
467
468=item *
469
8dab3ba5 470The deprecated variable C<PL_sv_objcount> has been removed.
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471
472=back
473
474=head1 Selected Bug Fixes
475
476XXX Important bug fixes in the core language are summarized here. Bug fixes in
477files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
478
479[ List each fix as a =item entry ]
480
481=over 4
482
483=item *
484
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485index() and rindex() no longer crash when used on strings over 2GB in
486size.
487L<[perl #121562]|https://rt.perl.org/Ticket/Display.html?id=121562>.
7065301c 488
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489=item *
490
491A small previously intentional memory leak in PERL_SYS_INIT/PERL_SYS_INIT3 on
492Win32 builds was fixed. This might affect embedders who repeatedly create and
493destroy perl engines within the same process.
494
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495=item *
496
497C<POSIX::localeconv()> now returns the data for the program's underlying
498locale even when called from outside the scope of S<C<use locale>>.
499
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500=item *
501
502C<POSIX::localeconv()> now works properly on platforms which don't have
503C<LC_NUMERIC> and/or C<LC_MONETARY>, or for which Perl has been compiled
504to disregard either or both of these locale categories. In such
505circumstances, there are now no entries for the corresponding values in
506the hash returned by C<localeconv()>.
507
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508=item *
509
510C<POSIX::localeconv()> now marks appropriately the values it returns as
511UTF-8 or not. Previously they were always returned as a bytes, even if
512they were supposed to be encoded as UTF-8.
513
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514=back
515
516=head1 Known Problems
517
518XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
519tests that had to be C<TODO>ed for the release would be noted here. Unfixed
520platform specific bugs also go here.
521
522[ List each fix as a =item entry ]
523
524=over 4
525
526=item *
527
528XXX
529
530=back
531
532=head1 Errata From Previous Releases
533
534=over 4
535
536=item *
537
538XXX Add anything here that we forgot to add, or were mistaken about, in
539the perldelta of a previous release.
540
541=back
542
543=head1 Obituary
544
545XXX If any significant core contributor has died, we've added a short obituary
546here.
547
548=head1 Acknowledgements
24a38d90 549
7065301c 550XXX Generate this with:
52e02e68 551
7065301c 552 perl Porting/acknowledgements.pl v5.21.1..HEAD
f5b73711 553
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554=head1 Reporting Bugs
555
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556If you find what you think is a bug, you might check the articles recently
557posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 558https://rt.perl.org/ . There may also be information at
7ef8b31d 559http://www.perl.org/ , the Perl Home Page.
44691e6f 560
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561If you believe you have an unreported bug, please run the L<perlbug> program
562included with your release. Be sure to trim your bug down to a tiny but
563sufficient test case. Your bug report, along with the output of C<perl -V>,
564will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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565
566If the bug you are reporting has security implications, which make it
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567inappropriate to send to a publicly archived mailing list, then please send it
568to perl5-security-report@perl.org. This points to a closed subscription
569unarchived mailing list, which includes all the core committers, who will be
570able to help assess the impact of issues, figure out a resolution, and help
f9001595 571co-ordinate the release of patches to mitigate or fix the problem across all
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572platforms on which Perl is supported. Please only use this address for
573security issues in the Perl core, not for modules independently distributed on
574CPAN.
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575
576=head1 SEE ALSO
577
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578The F<Changes> file for an explanation of how to view exhaustive details on
579what changed.
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580
581The F<INSTALL> file for how to build Perl.
582
583The F<README> file for general stuff.
584
585The F<Artistic> and F<Copying> files for copyright information.
586
587=cut