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perldelta for 8be3c4c
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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=head2 S<C<use locale>> can restrict which locale categories are affected
45
46It is now possible to pass a parameter to S<C<use locale>> to specify
47a subset of locale categories to be locale-aware, with the remaining
48ones unaffected. See L<perllocale/The "use locale" pragma> for details.
49
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50=head1 Security
51
52XXX Any security-related notices go here. In particular, any security
53vulnerabilities closed should be noted here rather than in the
54L</Selected Bug Fixes> section.
55
56[ List each security issue as a =head2 entry ]
57
58=head1 Incompatible Changes
59
60XXX For a release on a stable branch, this section aspires to be:
61
62 There are no changes intentionally incompatible with 5.XXX.XXX
63 If any exist, they are bugs, and we request that you submit a
64 report. See L</Reporting Bugs> below.
65
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66=head2 In double-quotish C<\cI<X>>, I<X> must now be a printable ASCII character
67
68In prior releases, failure to do this raised a deprecation warning.
7065301c 69
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70=head2 Splitting the tokens C<(?> and C<(*> in regular expressions is
71now a fatal compilation error.
72
73These had been deprecated since v5.18.
74
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75=head2 5 additional characters are treated as white space under C</x> in
76regex patterns (unless escaped)
77
78The use of these characters with C</x> outside bracketed character
79classes and when not preceeded by a backslash has raised a deprecation
80warning since v5.18. Now they will be ignored. See L</qrE<sol>fooE<sol>x>
81for the list of the five characters.
82
83=head2 Comment lines within S<C<(?[ ])>> now are ended only by a C<\n>
84
85S<C<(?[ ])>> is an experimental feature, introduced in v5.18. It operates
86as if C</x> is always enabled. But there was a difference, comment
87lines (following a C<#> character) were terminated by anything matching
88C<\R> which includes all vertical whitespace, such as form feeds. For
89consistency, this is now changed to match what terminates comment lines
90outside S<C<(?[ ])>>, namely a C<\n> (even if escaped), which is the
91same as what terminates a heredoc string and formats.
92
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93=head2 Omitting % and @ on hash and array names is no longer permitted
94
95Really old Perl let you omit the @ on array names and the % on hash
96names in some spots. This has issued a deprecation warning since Perl
975.0, and is no longer permitted.
98
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99=head2 C<"$!"> text is now in English outside C<"use locale"> scope
100
101Previously, the text, unlike almost everything else, always came out
102based on the current underlying locale of the program. (Also affected
103on some systems is C<"$^E>".) For programs that are unprepared to
104handle locale, this can cause garbage text to be displayed. It's better
105to display text that is translatable via some tool than garbage text
106which is much harder to figure out.
107
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108=head2 C<"$!"> text will be returned in UTF-8 when appropriate
109
110The stringification of C<$!> and C<$^E> will have the UTF-8 flag set
111when the text is actually non-ASCII UTF-8. This will enable programs
112that are set up to be locale-aware to properly output messages in the
113user's native language. Code that needs to continue the 5.20 and
114earlier behavior can do the stringification within the scopes of both
115'use bytes' and 'use locale ":messages". No other Perl operations will
116be affected by locale; only C<$!> and C<$^E> stringification. The
117'bytes' pragma causes the UTF-8 flag to not be set, just as in previous
118Perl releases. This resolves [perl #112208].
119
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120=head1 Deprecations
121
122XXX Any deprecated features, syntax, modules etc. should be listed here.
123
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124=head2 Using a NO-BREAK space in a character alias for C<\N{...}> is now
125deprecated
126
127This non-graphic character is essentially indistinguishable from a
128regular space, and so should not be allowed. See
129L<charnames/CUSTOM ALIASES>.
130
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131=head2 Module removals
132
133XXX Remove this section if inapplicable.
134
135The following modules will be removed from the core distribution in a
136future release, and will at that time need to be installed from CPAN.
137Distributions on CPAN which require these modules will need to list them as
138prerequisites.
139
140The core versions of these modules will now issue C<"deprecated">-category
141warnings to alert you to this fact. To silence these deprecation warnings,
142install the modules in question from CPAN.
143
144Note that these are (with rare exceptions) fine modules that you are encouraged
145to continue to use. Their disinclusion from core primarily hinges on their
146necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
147not usually on concerns over their design.
148
149=over
150
151=item XXX
152
153XXX Note that deprecated modules should be listed here even if they are listed
154as an updated module in the L</Modules and Pragmata> section.
155
156=back
157
158[ List each other deprecation as a =head2 entry ]
159
160=head1 Performance Enhancements
161
162XXX Changes which enhance performance without changing behaviour go here.
163There may well be none in a stable release.
164
165[ List each enhancement as a =item entry ]
166
167=over 4
168
169=item *
170
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171Many internal functions have been refactored to improve performance and reduce
172their memory footprints.
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173
174L<[perl #121436]|https://rt.perl.org/Ticket/Display.html?id=121436>
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175L<[perl #121906]|https://rt.perl.org/Ticket/Display.html?id=121906>
176L<[perl #121969]|https://rt.perl.org/Ticket/Display.html?id=121969>
7065301c 177
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178=item *
179
180C<-T> and C<-B> filetests will return sooner when an empty file is detected.
181
182L<perl #121489|https://rt.perl.org/Ticket/Display.html?id=121489>
183
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184=back
185
7ef8b31d 186=head1 Modules and Pragmata
f6f3144e 187
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188XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
189go here. If Module::CoreList is updated, generate an initial draft of the
190following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
191for important changes should then be added by hand. In an ideal world,
192dual-life modules would have a F<Changes> file that could be cribbed.
193
194[ Within each section, list entries as a =item entry ]
195
196=head2 New Modules and Pragmata
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197
198=over 4
199
200=item *
201
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202XXX
203
204=back
205
206=head2 Updated Modules and Pragmata
207
208=over 4
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209
210=item *
211
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212L<Carp> has been upgraded from version 1.3301 to 1.34.
213
214Carp::Heavy now ignores version mismatches with Carp if Carp is newer
215than 1.12, since Carp::Heavy's guts were merged into Carp at that
216point.
217L<[perl #121574]|https://rt.perl.org/Ticket/Display.html?id=121574>
218
219=item *
220
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221L<Encode> has been upgraded from version 2.60_01 to 2.62.
222
223B<piconv> now has better error handling when the encoding name is nonexistent,
224and a build breakage when upgrading L<Encode> in perl-5.8.2 and earlier has
225been fixed.
226
227=item *
228
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229The libnet collection of modules has been upgraded from version 1.25 to 1.27.
230
231There are only whitespace changes to the installed files.
232
233=item *
234
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235The Locale-Codes collection of modules has been upgraded from vesion 3.30 to 3.31.
236
237Fixed a bug in the scripts used to extract data from spreadsheets that
238prevented the SHP currency code from being found.
239L<[cpan #94229]|https://rt.cpan.org/Ticket/Display.html?id=94229>
240
241=item *
242
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243L<Math::BigInt> has been upgraded from version 1.9993 to 1.9994.
244
245Synchronize POD changes from the CPAN release.
246
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247C<< Math::BigFloat->blog(x) >> would sometimes return blog(2*x) when
248the accuracy was greater than 70 digits.
249
250The result of C<< Math::BigFloat->bdiv() >> in list context now
251satisfies C<< x = quotient * divisor + remainder >>.
252
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253=item *
254
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255L<Math::BigRat> has been upgraded from version 0.2606 to 0.2607.
256
257Synchronize POD changes from the CPAN release.
258
259=item *
260
f97d984b 261L<Module::Metadata> has been upgraded from version 1.000022 to 1.000024.
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262
263Support installations on older perls with an L<ExtUtils::MakeMaker> earlier
264than 6.63_03
265
266=item *
267
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268L<perl5db.pl> has been upgraded from version 1.44 to 1.45.
269
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270=item *
271
272A mismatch between the documentation and the code in utf8::downgrade()
273was fixed in favour of the documentation. The optional second argument
274is now correctly treated as a perl boolean (true/false semantics) and
275not as an integer.
276
277=item *
278
c13fd1a2 279fork() in the debugger under C<tmux> will now create a new window for
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280the forked process. L<[perl
281#121333]|https://rt.perl.org/Ticket/Display.html?id=121333>
282
283The debugger now saves the current working directory on startup and
284restores it when you restart your program with C<R> or <rerun>. L<[perl
285#121509]|https://rt.perl.org/Ticket/Display.html?id=121509>
24a38d90 286
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287L<Unicode::Collate> has been upgraded from version 1.04 to 1.07.
288
289Version 0.67's improved discontiguous contractions is invalidated by default
290and is supported as a parameter 'long_contraction'.
291
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292=item *
293
294L<Unicode::Normalize> has been upgraded from version 1.17 to 1.18.
295
296The XSUB implementation has been removed in favour of pure Perl.
297
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298=item *
299
300L<Hash::Util> has been upgraded from version 0.16 to 0.17.
301
302Minor bug fixes and documentation fixes to Hash::Util::hash_stats()
303
304
238894db 305=back
24a38d90 306
92fa985e 307=head2 Removed Modules and Pragmata
24a38d90 308
238894db 309=over 4
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310
311=item *
312
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313XXX
314
315=back
316
317=head1 Documentation
318
319XXX Changes to files in F<pod/> go here. Consider grouping entries by
320file and be sure to link to the appropriate page, e.g. L<perlfunc>.
321
322=head2 New Documentation
323
324XXX Changes which create B<new> files in F<pod/> go here.
325
326=head3 L<XXX>
327
328XXX Description of the purpose of the new file here
329
330=head2 Changes to Existing Documentation
331
332XXX Changes which significantly change existing files in F<pod/> go here.
333However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
334section.
335
9c0f2733 336=head3 L<perlfunc>
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337
338=over 4
339
340=item *
341
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342C<-l> now notes that it will return false if symlinks aren't supported by the
343file system.
344
345L<[perl #121523]|https://rt.perl.org/Ticket/Display.html?id=121523>
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346
347=back
348
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349=head3 L<perlapi>
350
351=over 4
352
353=item *
354
355C<sv_usepvn_flags> - Fix documentation to mention the use of C<NewX> instead of
356C<malloc>.
357
358L<[perl #121869]|https://rt.perl.org/Ticket/Display.html?id=121869>
359
360=back
361
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362=head3 L<perlhacktips>
363
364=over 4
365
366=item *
367
368Updated documentation for the C<test.valgrind> C<make> target.
369
370L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431>
371
372=back
373
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374=head3 L<perlre>
375
376=over 4
377
378=item *
379
380The C</x> modifier has been clarified to note that comments cannot be continued
381onto the next line by escaping them.
382
383=back
384
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385=head1 Diagnostics
386
387The following additions or changes have been made to diagnostic output,
388including warnings and fatal error messages. For the complete list of
389diagnostic messages, see L<perldiag>.
390
391XXX New or changed warnings emitted by the core's C<C> code go here. Also
392include any changes in L<perldiag> that reconcile it to the C<C> code.
393
394=head2 New Diagnostics
395
396XXX Newly added diagnostic messages go under here, separated into New Errors
397and New Warnings
398
399=head3 New Errors
400
401=over 4
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402
403=item *
404
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405XXX L<message|perldiag/"message">
406
407=back
408
409=head3 New Warnings
410
411=over 4
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412
413=item *
414
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415L<PerlIO layer ':win32' is experimental|perldiag/"PerlIO layer ':win32' is experimental">:
416
417(S experimental::win32_perlio) The C<:win32> PerlIO layer is
418experimental. If you want to take the risk of using this layer,
419simply disable this warning:
420
421 no warnings "experimental::win32_perlio";
24a38d90 422
238894db 423=back
24a38d90 424
7065301c 425=head2 Changes to Existing Diagnostics
24a38d90 426
7065301c 427XXX Changes (i.e. rewording) of diagnostic messages go here
24a38d90 428
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429=over 4
430
431=item *
432
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433L<Unsuccessful %s on filename containing newline|perldiag/"Unsuccessful %s on filename containing newline">
434
435This warning is now only produced when the newline is at the end of
436the filename.
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437
438=back
439
440=head1 Utility Changes
441
442XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
eb561242 443Most of these are built within the directory F<utils>.
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444
445[ List utility changes as a =head2 entry for each utility and =item
446entries for each change
447Use L<XXX> with program names to get proper documentation linking. ]
448
eb561242 449=head2 F<x2p/>
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450
451=over 4
452
453=item *
24a38d90 454
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455The F<x2p/> directory has been removed from the Perl core.
456
457This removes find2perl, s2p and a2p. They have all been released to CPAN as
458separate distributions (App::find2perl, App::s2p, App::a2p).
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459
460=back
461
462=head1 Configuration and Compilation
463
464XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
465go here. Any other changes to the Perl build process should be listed here.
466However, any platform-specific changes should be listed in the
467L</Platform Support> section, instead.
468
469[ List changes as a =item entry ].
470
471=over 4
472
473=item *
474
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475C<make test.valgrind> now supports parallel testing.
476
477For example:
478
479 TEST_JOBS=9 make test.valgrind
480
481See L<perlhacktips/valgrind> for more information.
482
483L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431>
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484
485=back
486
487=head1 Testing
488
489XXX Any significant changes to the testing of a freshly built perl should be
490listed here. Changes which create B<new> files in F<t/> go here as do any
491large changes to the testing harness (e.g. when parallel testing was added).
492Changes to existing files in F<t/> aren't worth summarizing, although the bugs
493that they represent may be covered elsewhere.
494
495[ List each test improvement as a =item entry ]
496
497=over 4
498
499=item *
500
501XXX
502
503=back
504
505=head1 Platform Support
506
507XXX Any changes to platform support should be listed in the sections below.
508
509[ Within the sections, list each platform as a =item entry with specific
510changes as paragraphs below it. ]
511
512=head2 New Platforms
513
514XXX List any platforms that this version of perl compiles on, that previous
515versions did not. These will either be enabled by new files in the F<hints/>
516directories, or new subdirectories and F<README> files at the top level of the
517source tree.
518
519=over 4
520
521=item XXX-some-platform
522
523XXX
524
525=back
526
527=head2 Discontinued Platforms
528
529XXX List any platforms that this version of perl no longer compiles on.
530
531=over 4
532
f05550c0 533=item NeXTSTEP/OPENSTEP
7065301c 534
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535NeXTSTEP was proprietary OS bundled with NeXT's workstations in the early
536to mid 90's; OPENSTEP was an API specification that provided a NeXTSTEP-like
537environment on a non-NeXTSTEP system. Both are now long dead, so support
538for building Perl on them has been removed.
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539
540=back
541
542=head2 Platform-Specific Notes
543
544XXX List any changes for specific platforms. This could include configuration
545and compilation changes or changes in portability/compatibility. However,
546changes within modules for platforms should generally be listed in the
547L</Modules and Pragmata> section.
548
549=over 4
550
551=item XXX-some-platform
552
553XXX
554
555=back
556
557=head1 Internal Changes
558
559XXX Changes which affect the interface available to C<XS> code go here. Other
560significant internal changes for future core maintainers should be noted as
561well.
562
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563=over 4
564
565=item *
566
8dab3ba5 567The deprecated variable C<PL_sv_objcount> has been removed.
7065301c 568
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569=item *
570
571Perl now tries to keep the locale category C<LC_NUMERIC> set to "C"
572except around operations that need it to be set to the program's
573underlying locale. This protects the many XS modules that cannot cope
574with the decimal radix character not being a dot. Prior to this
575release, Perl initialized this category to "C", but a call to
576C<POSIX::setlocale()> would change it. Now such a call will change the
577underlying locale of the C<LC_NUMERIC> category for the program, but the
578locale exposed to XS code will remain "C". There is an API under
579development for those relatively few modules that need to use the
580underlying locale. This API will be nailed down during the course of
581developing v5.21. Send email to L<mailto:perl5-porters@perl.org> for
582guidance.
583
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584=back
585
586=head1 Selected Bug Fixes
587
588XXX Important bug fixes in the core language are summarized here. Bug fixes in
589files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
590
591[ List each fix as a =item entry ]
592
593=over 4
594
595=item *
596
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597index() and rindex() no longer crash when used on strings over 2GB in
598size.
599L<[perl #121562]|https://rt.perl.org/Ticket/Display.html?id=121562>.
7065301c 600
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601=item *
602
603A small previously intentional memory leak in PERL_SYS_INIT/PERL_SYS_INIT3 on
604Win32 builds was fixed. This might affect embedders who repeatedly create and
605destroy perl engines within the same process.
606
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607=item *
608
609C<POSIX::localeconv()> now returns the data for the program's underlying
610locale even when called from outside the scope of S<C<use locale>>.
611
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612=item *
613
614C<POSIX::localeconv()> now works properly on platforms which don't have
615C<LC_NUMERIC> and/or C<LC_MONETARY>, or for which Perl has been compiled
616to disregard either or both of these locale categories. In such
617circumstances, there are now no entries for the corresponding values in
618the hash returned by C<localeconv()>.
619
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620=item *
621
622C<POSIX::localeconv()> now marks appropriately the values it returns as
623UTF-8 or not. Previously they were always returned as a bytes, even if
624they were supposed to be encoded as UTF-8.
625
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626=item *
627
628On Microsoft Windows, within the scope of C<S<use locale>>, the following
629POSIX character classes gave results for many locales that did not
630conform to the POSIX standard:
631C<[[:alnum:]]>,
632C<[[:alpha:]]>,
633C<[[:blank:]]>,
634C<[[:digit:]]>,
635C<[[:graph:]]>,
636C<[[:lower:]]>,
637C<[[:print:]]>,
638C<[[:punct:]]>,
639C<[[:upper:]]>,
640C<[[:word:]]>,
641and
642C<[[:xdigit:]]>.
643These are because the underlying Microsoft implementation does not
644follow the standard. Perl now takes special precautions to correct for
645this.
646
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647=item *
648
649Many issues have been detected by L<Coverity|http://www.coverity.com/> and
650fixed.
651
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652=back
653
654=head1 Known Problems
655
656XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
657tests that had to be C<TODO>ed for the release would be noted here. Unfixed
658platform specific bugs also go here.
659
660[ List each fix as a =item entry ]
661
662=over 4
663
664=item *
665
666XXX
667
668=back
669
670=head1 Errata From Previous Releases
671
672=over 4
673
674=item *
675
676XXX Add anything here that we forgot to add, or were mistaken about, in
677the perldelta of a previous release.
678
679=back
680
681=head1 Obituary
682
683XXX If any significant core contributor has died, we've added a short obituary
684here.
685
686=head1 Acknowledgements
24a38d90 687
7065301c 688XXX Generate this with:
52e02e68 689
7065301c 690 perl Porting/acknowledgements.pl v5.21.1..HEAD
f5b73711 691
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692=head1 Reporting Bugs
693
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694If you find what you think is a bug, you might check the articles recently
695posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 696https://rt.perl.org/ . There may also be information at
7ef8b31d 697http://www.perl.org/ , the Perl Home Page.
44691e6f 698
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699If you believe you have an unreported bug, please run the L<perlbug> program
700included with your release. Be sure to trim your bug down to a tiny but
701sufficient test case. Your bug report, along with the output of C<perl -V>,
702will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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703
704If the bug you are reporting has security implications, which make it
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705inappropriate to send to a publicly archived mailing list, then please send it
706to perl5-security-report@perl.org. This points to a closed subscription
707unarchived mailing list, which includes all the core committers, who will be
708able to help assess the impact of issues, figure out a resolution, and help
f9001595 709co-ordinate the release of patches to mitigate or fix the problem across all
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710platforms on which Perl is supported. Please only use this address for
711security issues in the Perl core, not for modules independently distributed on
712CPAN.
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713
714=head1 SEE ALSO
715
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716The F<Changes> file for an explanation of how to view exhaustive details on
717what changed.
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718
719The F<INSTALL> file for how to build Perl.
720
721The F<README> file for general stuff.
722
723The F<Artistic> and F<Copying> files for copyright information.
724
725=cut