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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 v5.21.4
c68523cb 9
238894db 10=head1 DESCRIPTION
c68523cb 11
39c4a6cf 12This document describes differences between the 5.21.3 release and the 5.21.4
238894db 13release.
c68523cb 14
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15If you are upgrading from an earlier release such as 5.21.2, first read
16L<perl5213delta>, which describes differences between 5.21.2 and 5.21.3.
7065301c 17
39c4a6cf 18=head1 Notice
7e957246 19
39c4a6cf 20XXX Any important notices here
7e957246 21
39c4a6cf 22=head1 Core Enhancements
f88f10f5 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.
21f3b41e 27
39c4a6cf 28[ List each enhancement as a =head2 entry ]
f88f10f5 29
0346c3a9 30=head1 Security
7e957246 31
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32XXX Any security-related notices go here. In particular, any security
33vulnerabilities closed should be noted here rather than in the
34L</Selected Bug Fixes> section.
13900f93 35
39c4a6cf 36[ List each security issue as a =head2 entry ]
8bdb3f93 37
13900f93 38=head1 Incompatible Changes
8bdb3f93 39
39c4a6cf 40XXX For a release on a stable branch, this section aspires to be:
1178d2cf 41
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42 There are no changes intentionally incompatible with 5.XXX.XXX
43 If any exist, they are bugs, and we request that you submit a
44 report. See L</Reporting Bugs> below.
1178d2cf 45
39c4a6cf 46[ List each incompatible change as a =head2 entry ]
f6f3144e 47
39c4a6cf 48=head1 Deprecations
7065301c 49
39c4a6cf 50XXX Any deprecated features, syntax, modules etc. should be listed here.
7065301c 51
39c4a6cf 52=head2 Module removals
b3e82ed1 53
39c4a6cf 54XXX Remove this section if inapplicable.
ca58223b 55
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56The following modules will be removed from the core distribution in a
57future release, and will at that time need to be installed from CPAN.
58Distributions on CPAN which require these modules will need to list them as
59prerequisites.
ca58223b 60
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61The core versions of these modules will now issue C<"deprecated">-category
62warnings to alert you to this fact. To silence these deprecation warnings,
63install the modules in question from CPAN.
23b03637 64
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65Note that these are (with rare exceptions) fine modules that you are encouraged
66to continue to use. Their disinclusion from core primarily hinges on their
67necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
68not usually on concerns over their design.
23b03637 69
39c4a6cf 70=over
85e8fb10 71
39c4a6cf 72=item XXX
85e8fb10 73
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74XXX Note that deprecated modules should be listed here even if they are listed
75as an updated module in the L</Modules and Pragmata> section.
134f90c2 76
39c4a6cf 77=back
134f90c2 78
39c4a6cf 79[ List each other deprecation as a =head2 entry ]
ff433f2d 80
39c4a6cf 81=head1 Performance Enhancements
ff433f2d 82
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83XXX Changes which enhance performance without changing behaviour go here.
84There may well be none in a stable release.
134f90c2 85
39c4a6cf 86[ List each enhancement as a =item entry ]
134f90c2 87
39c4a6cf 88=over 4
7d19f6a1 89
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90=item *
91
39c4a6cf 92XXX
55e8b286 93
39c4a6cf 94=back
55e8b286 95
39c4a6cf 96=head1 Modules and Pragmata
d99849ae 97
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98XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
99go here. If Module::CoreList is updated, generate an initial draft of the
100following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
101for important changes should then be added by hand. In an ideal world,
102dual-life modules would have a F<Changes> file that could be cribbed.
d99849ae 103
39c4a6cf 104[ Within each section, list entries as a =item entry ]
ff433f2d 105
39c4a6cf 106=head2 New Modules and Pragmata
ff433f2d 107
39c4a6cf 108=over 4
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109
110=item *
111
39c4a6cf 112XXX
0bb39c26 113
39c4a6cf 114=back
0bb39c26 115
39c4a6cf 116=head2 Updated Modules and Pragmata
9c97a342 117
39c4a6cf 118=over 4
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119
120=item *
121
39c4a6cf 122L<XXX> has been upgraded from version A.xx to B.yy.
6ab3666b 123
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124=item *
125
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126L<B::Concise> has been upgraded from version 0.992 to 0.993.
127
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128=item *
129
130L<CPAN::Meta::Requirements> has been upgraded from version 2.126 to 2.128.
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131
132=item *
133
134L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280219.
135[perl #122675].
136
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137=item *
138
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139L<ExtUtils::Manifest> has been upgraded from version 1.65 to 1.66.
140[perl #122415].
141
142=item *
143
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144L<ExtUtils::ParseXS>: Documentation has been added to
145F<ExtUtils-ParseXS/lib/perlxs.pod> concerning handling of locales when writing
146XS code.
147
148=item *
149
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150L<File::Find> has been upgraded from version 1.27 to 1.28.
151
152C<find()> and C<finddepth()> will now warn if passed inappropriate or
153misspelled options.
154
155=item *
156
157L<Getopt::Std> has been upgraded from version 1.10 to 1.11.
158
159=item *
160
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161L<HTTP::Tiny> has been upgraded from version 0.047 to 0.048.
162
163=item *
164
165L<Module::CoreList> has been upgraded from version 5.021003 to 5.021004.
166
167=item *
168
169L<POSIX> has been upgraded from version 1.42 to 1.43.
170
171=item *
172
173L<Pod::Perldoc> has been upgraded from version 3.23 to 3.24.
174
175=item *
176
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177Scalar-List-Utils has been upgraded from version 1.40 to 1.41.
178
179=item *
180
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181L<constant> has been upgraded from version 1.31 to 1.32.
182
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183It now accepts fully-qualified constant names, allowing constants to be
184defined in packages other than the caller.
185
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186=item *
187
188L<threads> has been upgraded from version 1.95 to 1.96.
189
39c4a6cf 190=back
9c97a342 191
39c4a6cf 192=head2 Removed Modules and Pragmata
d99849ae 193
39c4a6cf 194=over 4
d99849ae 195
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196=item *
197
39c4a6cf 198XXX
ff433f2d 199
13900f93 200=back
aac7f82f 201
13900f93 202=head1 Documentation
aac7f82f 203
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204XXX Changes to files in F<pod/> go here. Consider grouping entries by
205file and be sure to link to the appropriate page, e.g. L<perlfunc>.
6d9b7c7c 206
39c4a6cf 207=head2 New Documentation
2a395b86 208
39c4a6cf 209XXX Changes which create B<new> files in F<pod/> go here.
2a395b86 210
39c4a6cf 211=head3 L<XXX>
2a395b86 212
39c4a6cf 213XXX Description of the purpose of the new file here
2a395b86 214
39c4a6cf 215=head2 Changes to Existing Documentation
2a395b86 216
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217XXX Changes which significantly change existing files in F<pod/> go here.
218However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
219section.
220
221=head3 L<XXX>
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222
223=over 4
224
225=item *
226
39c4a6cf 227XXX Description of the change here
2a395b86 228
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229=item *
230
231L<perlsyn>: An ambiguity in the documentation of the Ellipsis statement has
232been corrected. [perl #122661]
233
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234=back
235
39c4a6cf 236=head1 Diagnostics
2a395b86 237
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238The following additions or changes have been made to diagnostic output,
239including warnings and fatal error messages. For the complete list of
240diagnostic messages, see L<perldiag>.
2a395b86 241
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242XXX New or changed warnings emitted by the core's C<C> code go here. Also
243include any changes in L<perldiag> that reconcile it to the C<C> code.
2a395b86 244
39c4a6cf 245=head2 New Diagnostics
0f4a583b 246
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247XXX Newly added diagnostic messages go under here, separated into New Errors
248and New Warnings
2a395b86 249
39c4a6cf 250=head3 New Errors
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251
252=over 4
253
254=item *
255
39c4a6cf 256XXX L<message|perldiag/"message">
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257
258=back
259
39c4a6cf 260=head3 New Warnings
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261
262=over 4
263
264=item *
265
39c4a6cf 266XXX L<message|perldiag/"message">
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267
268=back
6d9b7c7c 269
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270=head2 Changes to Existing Diagnostics
271
272XXX Changes (i.e. rewording) of diagnostic messages go here
7f55cec0 273
13900f93 274=over 4
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275
276=item *
277
39c4a6cf 278XXX Describe change here
aac7f82f 279
13900f93 280=back
aac7f82f 281
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282=head2 Diagnostic Removals
283
284=over 4
285
286=item *
287
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288"Constant is not a FOO reference"
289
290Compile-time checking of constant dereferencing (e.g.,
291C<< my_constant->() >>) has been removed, since it was not taking
292overloading into account. [perl #69456] [perl #122607]
293
294=item *
295
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296The warning "Ambiguous use of -foo resolved as -&foo()" has been removed.
297There is actually no ambiguity here, and this impedes the use of negated
298constants; e.g., C<-Inf>.
299
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300=item *
301
302The little-known C<my Class $var> syntax (see L<fields> and L<attributes>)
303could get confused in the scope of C<use utf8> if C<Class> were a constant
304whose value contained Latin-1 characters.
305
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306=back
307
39c4a6cf 308=head1 Utility Changes
091fed7c 309
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310XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
311Most of these are built within the directory F<utils>.
902c1f75 312
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313[ List utility changes as a =head2 entry for each utility and =item
314entries for each change
315Use L<XXX> with program names to get proper documentation linking. ]
2901561d 316
39c4a6cf 317=head2 L<XXX>
4594cf53 318
13900f93 319=over 4
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320
321=item *
322
39c4a6cf 323XXX
a1d26ccd 324
39c4a6cf 325=back
a1d26ccd 326
39c4a6cf 327=head1 Configuration and Compilation
7065301c 328
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329XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
330go here. Any other changes to the Perl build process should be listed here.
331However, any platform-specific changes should be listed in the
332L</Platform Support> section, instead.
58f25ac1 333
39c4a6cf 334[ List changes as a =item entry ].
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335
336=over 4
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337
338=item *
339
39c4a6cf 340XXX
a5873648 341
39c4a6cf 342=back
a5873648 343
39c4a6cf 344=head1 Testing
a5873648 345
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346XXX Any significant changes to the testing of a freshly built perl should be
347listed here. Changes which create B<new> files in F<t/> go here as do any
348large changes to the testing harness (e.g. when parallel testing was added).
349Changes to existing files in F<t/> aren't worth summarizing, although the bugs
350that they represent may be covered elsewhere.
a5873648 351
39c4a6cf 352[ List each test improvement as a =item entry ]
a5873648 353
39c4a6cf 354=over 4
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355
356=item *
357
39c4a6cf 358XXX
a5873648 359
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360=back
361
39c4a6cf 362=head1 Platform Support
b10906fb 363
39c4a6cf 364XXX Any changes to platform support should be listed in the sections below.
b10906fb 365
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366[ Within the sections, list each platform as a =item entry with specific
367changes as paragraphs below it. ]
b10906fb 368
39c4a6cf 369=head2 New Platforms
b10906fb 370
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371XXX List any platforms that this version of perl compiles on, that previous
372versions did not. These will either be enabled by new files in the F<hints/>
373directories, or new subdirectories and F<README> files at the top level of the
374source tree.
13900f93 375
7065301c 376=over 4
24a38d90 377
39c4a6cf 378=item XXX-some-platform
24a38d90 379
39c4a6cf 380XXX
bb076206 381
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382=back
383
39c4a6cf 384=head2 Discontinued Platforms
097675bf 385
39c4a6cf 386XXX List any platforms that this version of perl no longer compiles on.
b3211734 387
6e97d65d 388=over 4
b3211734 389
39c4a6cf 390=item XXX-some-platform
7065301c 391
39c4a6cf 392XXX
13900f93 393
39c4a6cf 394=back
7d0ccdba 395
39c4a6cf 396=head2 Platform-Specific Notes
7d0ccdba 397
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398XXX List any changes for specific platforms. This could include configuration
399and compilation changes or changes in portability/compatibility. However,
400changes within modules for platforms should generally be listed in the
401L</Modules and Pragmata> section.
6e97d65d 402
39c4a6cf 403=over 4
6e97d65d 404
39c4a6cf 405=item XXX-some-platform
6e97d65d 406
39c4a6cf 407XXX
7d0ccdba 408
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409=back
410
411=head1 Internal Changes
412
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413XXX Changes which affect the interface available to C<XS> code go here. Other
414significant internal changes for future core maintainers should be noted as
415well.
c9fcb674 416
39c4a6cf 417[ List each change as a =item entry ]
a835cd47 418
39c4a6cf 419=over 4
c1284011 420
7d15b1a8 421XXX
1c43698b 422
6d9b7c7c 423=back
c1284011 424
6d9b7c7c 425=head1 Selected Bug Fixes
375f5f06 426
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427XXX Important bug fixes in the core language are summarized here. Bug fixes in
428files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
429
430[ List each fix as a =item entry ]
431
0346c3a9 432=over 4
375f5f06 433
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434=item *
435
39c4a6cf 436XXX
2884baee 437
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438=item *
439
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440Constant dereferencing now works correctly for typeglob constants.
441Previously the glob was stringified and its name looked up. Now the glob
442itself is used. [perl #69456]
443
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444=item *
445
446When parsing a funny character ($ @ % &) followed by braces, the parser no
447longer tries to guess whether it is a block or a hash constructor (causing
448a syntax error when it guesses the latter), since it can only be a block.
449
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450=item *
451
452C<undef $reference> now frees the referent immediately, instead of hanging
453on to it until the next statement. [perl #122556]
454
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455=item *
456
457Various cases where the name of a sub is used (autoload, overloading, error
458messages) used to crash for lexical subs, but have been fixed.
459
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460=item *
461
462Bareword lookup now tries to avoid vivifying packages if it turns out the
463bareword is not going to be a subroutine name.
464
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465=item *
466
467Compilation of anonymous constants (e.g., C<sub () { 3 }>) no longer
468deletes any subroutine named C<__ANON__> in the current package. Not only
469was C<*__ANON__{CODE}> cleared, but there was a memory leak, too. This bug
470goes back to perl 5.8.0.
471
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472=item *
473
474Stub declarations like C<sub f;> and C<sub f ();> no longer wipe out
475constants of the same name declared by C<use constant>. This bug was
476introduced in perl 5.10.0.
477
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478=item *
479
480Under some conditions a warning raised in compilation of regular
481expression patterns could be displayed multiple times. This is now
482fixed.
483
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484=item *
485
486C<qr/[\N{named sequence}]/> now works properly in many instances. Some
487names known to C<\N{...}> refer to a sequence of multiple characters,
488instead of the usual single character. Bracketed character classes
489generally only match single characters, but now special handling has
490been added so that they can match named sequences, but not if the class
491is inverted or the sequence is specified as the beginning or end of a
492range. In these cases, the only behavior change from before is a slight
493rewording of the fatal error message given when this class is part of a
494C<?[...])> construct. When the C<[...]> stands alone, the same
495non-fatal warning as before is raised, and only the first character in
496the sequence is used, again just as before.
497
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498=item *
499
500Tainted constants evaluated at compile time no longer cause unrelated
501statements to become tainted. [perl #122669]
502
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503=item *
504
505C<open $$fh, ...>, which vivifies a handle with a name like "main::_GEN_0",
506was not giving the handle the right reference count, so a double free could
507happen.
508
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509=item *
510
511When deciding that a bareword was a method name, the parser would get
512confused if an "our" sub with the same name existed, and look up the method
513in the package of the "our" sub, instead of the package of the invocant.
514
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515=item *
516
517The parser no longer gets confused by C<\U=> within a double-quoted string.
518It used to roduce a syntax error, but now compiles it correctly.
519[perl #80368]
520
39c4a6cf 521=back
b756670b 522
39c4a6cf 523=head1 Known Problems
b756670b 524
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525XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
526tests that had to be C<TODO>ed for the release would be noted here. Unfixed
527platform specific bugs also go here.
e917e94e 528
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529[ List each fix as a =item entry ]
530
531=over 4
e917e94e 532
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533=item *
534
39c4a6cf 535XXX
26dd5fd6 536
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537=back
538
39c4a6cf 539=head1 Errata From Previous Releases
e831f11a 540
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541=over 4
542
543=item *
ff433f2d 544
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545XXX Add anything here that we forgot to add, or were mistaken about, in
546the perldelta of a previous release.
ff433f2d 547
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548=back
549
550=head1 Obituary
ff433f2d 551
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552XXX If any significant core contributor has died, we've added a short obituary
553here.
ff433f2d 554
39c4a6cf 555=head1 Acknowledgements
ff433f2d 556
39c4a6cf 557XXX Generate this with:
e831f11a 558
39c4a6cf 559 perl Porting/acknowledgements.pl v5.21.3..HEAD
f5b73711 560
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561=head1 Reporting Bugs
562
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563If you find what you think is a bug, you might check the articles recently
564posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 565https://rt.perl.org/ . There may also be information at
7ef8b31d 566http://www.perl.org/ , the Perl Home Page.
44691e6f 567
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568If you believe you have an unreported bug, please run the L<perlbug> program
569included with your release. Be sure to trim your bug down to a tiny but
570sufficient test case. Your bug report, along with the output of C<perl -V>,
571will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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572
573If the bug you are reporting has security implications, which make it
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574inappropriate to send to a publicly archived mailing list, then please send it
575to perl5-security-report@perl.org. This points to a closed subscription
576unarchived mailing list, which includes all the core committers, who will be
577able to help assess the impact of issues, figure out a resolution, and help
f9001595 578co-ordinate the release of patches to mitigate or fix the problem across all
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579platforms on which Perl is supported. Please only use this address for
580security issues in the Perl core, not for modules independently distributed on
581CPAN.
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582
583=head1 SEE ALSO
584
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585The F<Changes> file for an explanation of how to view exhaustive details on
586what changed.
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587
588The F<INSTALL> file for how to build Perl.
589
590The F<README> file for general stuff.
591
592The F<Artistic> and F<Copying> files for copyright information.
593
594=cut