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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 v5.21.8
c68523cb 9
238894db 10=head1 DESCRIPTION
c68523cb 11
b5d4d3b9 12This document describes differences between the 5.21.7 release and the 5.21.8
238894db 13release.
c68523cb 14
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15If you are upgrading from an earlier release such as 5.21.6, first read
16L<perl5217delta>, which describes differences between 5.21.6 and 5.21.7.
2ec11c70 17
b5d4d3b9 18=head1 Notice
2ec11c70 19
b5d4d3b9 20XXX Any important notices here
67f2cc75 21
b5d4d3b9 22=head1 Core Enhancements
67f2cc75 23
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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.
67f2cc75 27
b5d4d3b9 28[ List each enhancement as a =head2 entry ]
295f7815 29
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30=head2 The warnings pragma now supports warnings outside of "all"
31
32Ever since perl v5.6.0 we've had no way of adding new warnings without
33retroactively adding them to all existing programs that used C<-w>,
34C<-W> or C<use warnings>.
35
36This caused us to not add new useful warnings out of fear that they
37might unduly burden users who just wanted to upgrade perl and didn't
38want to deal with a bunch of warnings from their existing code.
39
40We now support a way to have our cake and eat it too, and can add new
41warnings to the core going forward through other top-level warning
42categories. See L<the warnings documentation|warnings/Top-level
43warning categories & associated confusion> for details.
44
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45=head2 Non-Capturing Regular Expression Flag
46
47Regular expressions now support a C</n> flag that disables capturing
48and filling in C<$1>, C<$2>, etc... inside of groups:
49
50 "hello" =~ /(hi|hello)/n; # $1 is not set
51
52This is equivalent to putting C<?:> at the beginning of every capturing group.
53
54See L<perlre/"n"> for more information.
55
b5d4d3b9 56=head1 Security
3f22ed99 57
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58XXX Any security-related notices go here. In particular, any security
59vulnerabilities closed should be noted here rather than in the
60L</Selected Bug Fixes> section.
3f22ed99 61
b5d4d3b9 62[ List each security issue as a =head2 entry ]
aafa61ee 63
b5d4d3b9 64=head1 Incompatible Changes
ef8784b7 65
b5d4d3b9 66XXX For a release on a stable branch, this section aspires to be:
ef8784b7 67
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68 There are no changes intentionally incompatible with 5.XXX.XXX
69 If any exist, they are bugs, and we request that you submit a
70 report. See L</Reporting Bugs> below.
0a7766ab 71
b5d4d3b9 72[ List each incompatible change as a =head2 entry ]
0a7766ab 73
4dc623f0 74=head1 Deprecations
5b306eef 75
b5d4d3b9 76XXX Any deprecated features, syntax, modules etc. should be listed here.
c0659f73 77
b5d4d3b9 78=head2 Module removals
c0659f73 79
b5d4d3b9 80XXX Remove this section if inapplicable.
6ed80d55 81
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82The following modules will be removed from the core distribution in a
83future release, and will at that time need to be installed from CPAN.
84Distributions on CPAN which require these modules will need to list them as
85prerequisites.
6ed80d55 86
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87The core versions of these modules will now issue C<"deprecated">-category
88warnings to alert you to this fact. To silence these deprecation warnings,
89install the modules in question from CPAN.
6ed80d55 90
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91Note that these are (with rare exceptions) fine modules that you are encouraged
92to continue to use. Their disinclusion from core primarily hinges on their
93necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
94not usually on concerns over their design.
6ed80d55 95
b5d4d3b9 96=over
bb6a367a 97
b5d4d3b9 98=item XXX
6ed80d55 99
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100XXX Note that deprecated modules should be listed here even if they are listed
101as an updated module in the L</Modules and Pragmata> section.
f348c3d8 102
b5d4d3b9 103=back
7635ad4d 104
b5d4d3b9 105[ List each other deprecation as a =head2 entry ]
7635ad4d 106
b5d4d3b9 107=head1 Performance Enhancements
7635ad4d 108
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109XXX Changes which enhance performance without changing behaviour go here.
110There may well be none in a stable release.
60dde9d3 111
b5d4d3b9 112[ List each enhancement as a =item entry ]
60dde9d3 113
b5d4d3b9 114=over 4
f348c3d8 115
6ed80d55 116=item *
f348c3d8 117
b5d4d3b9 118XXX
cd3802ac 119
b5d4d3b9 120=back
cd3802ac 121
b5d4d3b9 122=head1 Modules and Pragmata
d6c13051 123
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124XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
125go here. If Module::CoreList is updated, generate an initial draft of the
126following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
127for important changes should then be added by hand. In an ideal world,
128dual-life modules would have a F<Changes> file that could be cribbed.
02a0bddf 129
b5d4d3b9 130[ Within each section, list entries as a =item entry ]
128f4e12 131
b5d4d3b9 132=head2 New Modules and Pragmata
cd3802ac 133
b5d4d3b9 134=over 4
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135
136=item *
137
b5d4d3b9 138XXX
3aba4f3d 139
b5d4d3b9 140=back
af292847 141
b5d4d3b9 142=head2 Updated Modules and Pragmata
190f5bb6 143
b5d4d3b9 144=over 4
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145
146=item *
147
b5d4d3b9 148L<XXX> has been upgraded from version A.xx to B.yy.
190f5bb6 149
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150=item *
151
152L<B> has been upgraded from version 1.54 to 1.55.
153
154A bug where, after an ithread creation or psuedofork, special/immortal SVs in
155the child ithread/psuedoprocess did not have the correct class of
156C<B::SPECIAL>, has been fixed.
157
b5d4d3b9 158=back
ba31029d 159
b5d4d3b9 160=head2 Removed Modules and Pragmata
b045b8b5 161
b5d4d3b9 162=over 4
aa67537d 163
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164=item *
165
b5d4d3b9 166XXX
4c7a0d98 167
b5d4d3b9 168=back
4c7a0d98 169
b5d4d3b9 170=head1 Documentation
f4eedc6b 171
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172XXX Changes to files in F<pod/> go here. Consider grouping entries by
173file and be sure to link to the appropriate page, e.g. L<perlfunc>.
f4eedc6b 174
b5d4d3b9 175=head2 New Documentation
6ed80d55 176
b5d4d3b9 177XXX Changes which create B<new> files in F<pod/> go here.
f348c3d8 178
b5d4d3b9 179=head3 L<XXX>
f348c3d8 180
b5d4d3b9 181XXX Description of the purpose of the new file here
f348c3d8 182
b5d4d3b9 183=head2 Changes to Existing Documentation
f348c3d8 184
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185XXX Changes which significantly change existing files in F<pod/> go here.
186However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
187section.
f348c3d8 188
b5d4d3b9 189=head3 L<XXX>
f348c3d8 190
b5d4d3b9 191=over 4
6ed80d55 192
60dde9d3 193=item *
f348c3d8 194
b5d4d3b9 195XXX Description of the change here
4dc623f0 196
b5d4d3b9 197=back
84d03adf 198
b5d4d3b9 199=head1 Diagnostics
ff433f2d 200
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201The following additions or changes have been made to diagnostic output,
202including warnings and fatal error messages. For the complete list of
203diagnostic messages, see L<perldiag>.
4cd408ba 204
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205XXX New or changed warnings emitted by the core's C<C> code go here. Also
206include any changes in L<perldiag> that reconcile it to the C<C> code.
6ed80d55 207
b5d4d3b9 208=head2 New Diagnostics
6ed80d55 209
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210XXX Newly added diagnostic messages go under here, separated into New Errors
211and New Warnings
6ed80d55 212
b5d4d3b9 213=head3 New Errors
f348c3d8 214
b5d4d3b9 215=over 4
ab0b796c 216
60dde9d3 217=item *
8c6180a9 218
b5d4d3b9 219XXX L<message|perldiag/"message">
8c6180a9 220
b5d4d3b9 221=back
0561e60b 222
b5d4d3b9 223=head3 New Warnings
dd200dff 224
b5d4d3b9 225=over 4
dd200dff 226
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227=item *
228
b5d4d3b9 229XXX L<message|perldiag/"message">
73e793fc 230
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231=item *
232
233L<Wide character (U+%X) in %s|perldiag/"Wide character (U+%X) in %s">
234
b5d4d3b9 235=back
8c6180a9 236
b5d4d3b9 237=head2 Changes to Existing Diagnostics
0561e60b 238
b5d4d3b9 239XXX Changes (i.e. rewording) of diagnostic messages go here
4a328228 240
b5d4d3b9 241=over 4
4cd408ba 242
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243=item *
244
b5d4d3b9 245XXX Describe change here
1861205d 246
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247The message
248L<Locale '%s' may not work well.%s|perldiag/"Locale '%s' may not work well.%s">
249is no longer raised unless the problemtatic locale is actually used in
250the Perl program. Previously it was raised if it merely was the
251underlying locale. All Perl programs have an underlying locale at all
252times, but something like a C<S<use locale>> is needed for that locale
253to actually have some effect. This message will not be raised when
254the underlying locale is hidden.
255
b5d4d3b9 256=back
40a81b59 257
b5d4d3b9 258=head1 Utility Changes
2a395b86 259
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260XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
261Most of these are built within the directory F<utils>.
2a395b86 262
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263[ List utility changes as a =head2 entry for each utility and =item
264entries for each change
265Use L<XXX> with program names to get proper documentation linking. ]
12d22d1f 266
b5d4d3b9 267=head2 L<XXX>
2a395b86 268
b5d4d3b9 269=over 4
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270
271=item *
272
b5d4d3b9 273XXX
bb8c7e27 274
b5d4d3b9 275=back
bb8c7e27 276
b5d4d3b9 277=head1 Configuration and Compilation
bb8c7e27 278
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279XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
280go here. Any other changes to the Perl build process should be listed here.
281However, any platform-specific changes should be listed in the
282L</Platform Support> section, instead.
aa292ef2 283
b5d4d3b9 284[ List changes as a =item entry ].
83b69bfd 285
b5d4d3b9 286=over 4
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287
288=item *
289
b5d4d3b9 290XXX
13adb056 291
b5d4d3b9 292=back
391823f2 293
b5d4d3b9 294=head1 Testing
6ff8f256 295
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296XXX Any significant changes to the testing of a freshly built perl should be
297listed here. Changes which create B<new> files in F<t/> go here as do any
298large changes to the testing harness (e.g. when parallel testing was added).
299Changes to existing files in F<t/> aren't worth summarizing, although the bugs
300that they represent may be covered elsewhere.
80cc3290 301
b5d4d3b9 302[ List each test improvement as a =item entry ]
60dde9d3 303
b5d4d3b9 304=over 4
db98db4e 305
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306=item *
307
b5d4d3b9 308XXX
9d22ccf6 309
b5d4d3b9 310=back
480961b6 311
b5d4d3b9 312=head1 Platform Support
480961b6 313
b5d4d3b9 314XXX Any changes to platform support should be listed in the sections below.
94c9bf90 315
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316[ Within the sections, list each platform as a =item entry with specific
317changes as paragraphs below it. ]
94c9bf90 318
b5d4d3b9 319=head2 New Platforms
8af808bf 320
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321XXX List any platforms that this version of perl compiles on, that previous
322versions did not. These will either be enabled by new files in the F<hints/>
323directories, or new subdirectories and F<README> files at the top level of the
324source tree.
8af808bf 325
b5d4d3b9 326=over 4
fdcaecb7 327
b5d4d3b9 328=item XXX-some-platform
fdcaecb7 329
b5d4d3b9 330XXX
2af7c6b6 331
4dc623f0 332=back
2af7c6b6 333
b5d4d3b9 334=head2 Discontinued Platforms
60dde9d3 335
b5d4d3b9 336XXX List any platforms that this version of perl no longer compiles on.
c0b32823 337
4dc623f0 338=over 4
b1a4e8b3 339
b5d4d3b9 340=item XXX-some-platform
b1a4e8b3 341
b5d4d3b9 342XXX
9e26817d 343
4dc623f0 344=back
9e26817d 345
4dc623f0 346=head2 Platform-Specific Notes
70cee83f 347
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348XXX List any changes for specific platforms. This could include configuration
349and compilation changes or changes in portability/compatibility. However,
350changes within modules for platforms should generally be listed in the
351L</Modules and Pragmata> section.
70cee83f 352
b5d4d3b9 353=over 4
e5fbfbc1 354
b4045391 355=item Win32
e5fbfbc1 356
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357=over 4
358
359=item *
360
361Previously, on Visual C++ for Win64 built Perls only, when compiling every Perl
362XS module (including CPAN ones) and Perl aware .c file with a 64 bit Visual C++,
363would uncondtionally have around a dozen warnings from hv_func.h. These
364warnings have been silenced. GCC all bitness and Visual C++ for Win32 were
365not affected.
366
367=back
353075a0 368
4dc623f0 369=back
353075a0 370
4dc623f0 371=head1 Internal Changes
9f122eef 372
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373XXX Changes which affect the interface available to C<XS> code go here. Other
374significant internal changes for future core maintainers should be noted as
375well.
bd2aa467 376
b5d4d3b9 377[ List each change as a =item entry ]
2ec11c70 378
b5d4d3b9 379=over 4
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380
381=item *
382
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383Added Perl_sv_get_backrefs() to determine if an SV is a weak-referent.
384
385Function either returns an SV * of type AV, which contains the set of
386weakreferences which reference the passed in SV, or a simple RV * which
387is the only weakref to this item.
388
389=item *
390
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391C<gv_add_by_type> which was added to public API in 5.11.0 but undocumented and
392shows no CPAN usage has been removed from public API. Please use public API
393C<GvSVn> C<GvIOn> C<GvAVn> and C<GvHVn> for adding elements to a GV.
394
395=item *
396
397C<GvSVn> C<GvIOn> C<GvAVn> and C<GvHVn> have been made rvalues, previously they
398were lvalues. If you are assigning a SV to C<GvSVn> C<GvIOn> C<GvAVn> and
399C<GvHVn> you are leaking memory. If you want an lvalue, use C<GvSV> C<GvIO>
400C<GvAV> and C<GvHV>.
401
402=item *
403
b5d4d3b9 404XXX
2ec11c70 405
4dc623f0 406=back
c7f058f0 407
4dc623f0 408=head1 Selected Bug Fixes
0ef4323a 409
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410XXX Important bug fixes in the core language are summarized here. Bug fixes in
411files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
279aef25 412
b5d4d3b9 413[ List each fix as a =item entry ]
00ba25b8 414
b5d4d3b9 415=over 4
00ba25b8 416
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417=item *
418
b5d4d3b9 419XXX
fcfb7b86 420
b5d4d3b9 421=back
fcfb7b86 422
b5d4d3b9 423=head1 Known Problems
8bb83ec2 424
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425XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
426tests that had to be C<TODO>ed for the release would be noted here. Unfixed
427platform specific bugs also go here.
8bb83ec2 428
b5d4d3b9 429[ List each fix as a =item entry ]
1318b6d7 430
b5d4d3b9 431=over 4
1318b6d7 432
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433=item *
434
b5d4d3b9 435XXX
070733df 436
b5d4d3b9 437=back
219f8441 438
b5d4d3b9 439=head1 Errata From Previous Releases
219f8441 440
b5d4d3b9 441=over 4
5747f88b 442
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443=item *
444
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445XXX Add anything here that we forgot to add, or were mistaken about, in
446the perldelta of a previous release.
61a8c397 447
86372193 448=back
bb8c7e27 449
b5d4d3b9 450=head1 Obituary
3a085d00 451
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452XXX If any significant core contributor has died, we've added a short obituary
453here.
01d42a22 454
b5d4d3b9 455=head1 Acknowledgements
01d42a22 456
b5d4d3b9 457XXX Generate this with:
01d42a22 458
b5d4d3b9 459 perl Porting/acknowledgements.pl v5.21.7..HEAD
f5b73711 460
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461=head1 Reporting Bugs
462
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463If you find what you think is a bug, you might check the articles recently
464posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 465https://rt.perl.org/ . There may also be information at
7ef8b31d 466http://www.perl.org/ , the Perl Home Page.
44691e6f 467
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468If you believe you have an unreported bug, please run the L<perlbug> program
469included with your release. Be sure to trim your bug down to a tiny but
470sufficient test case. Your bug report, along with the output of C<perl -V>,
471will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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472
473If the bug you are reporting has security implications, which make it
e08634c5
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474inappropriate to send to a publicly archived mailing list, then please send it
475to perl5-security-report@perl.org. This points to a closed subscription
476unarchived mailing list, which includes all the core committers, who will be
477able to help assess the impact of issues, figure out a resolution, and help
f9001595 478co-ordinate the release of patches to mitigate or fix the problem across all
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479platforms on which Perl is supported. Please only use this address for
480security issues in the Perl core, not for modules independently distributed on
481CPAN.
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482
483=head1 SEE ALSO
484
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485The F<Changes> file for an explanation of how to view exhaustive details on
486what changed.
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487
488The F<INSTALL> file for how to build Perl.
489
490The F<README> file for general stuff.
491
492The F<Artistic> and F<Copying> files for copyright information.
493
494=cut