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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
233a4069
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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<File::Find> has been upgraded from version 1.27 to 1.28.
145
146C<find()> and C<finddepth()> will now warn if passed inappropriate or
147misspelled options.
148
149=item *
150
151L<Getopt::Std> has been upgraded from version 1.10 to 1.11.
152
153=item *
154
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155L<HTTP::Tiny> has been upgraded from version 0.047 to 0.048.
156
157=item *
158
159L<Module::CoreList> has been upgraded from version 5.021003 to 5.021004.
160
161=item *
162
163L<POSIX> has been upgraded from version 1.42 to 1.43.
164
165=item *
166
167L<Pod::Perldoc> has been upgraded from version 3.23 to 3.24.
168
169=item *
170
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171Scalar-List-Utils has been upgraded from version 1.40 to 1.41.
172
173=item *
174
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175L<constant> has been upgraded from version 1.31 to 1.32.
176
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177It now accepts fully-qualified constant names, allowing constants to be
178defined in packages other than the caller.
179
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180=item *
181
182L<threads> has been upgraded from version 1.95 to 1.96.
183
39c4a6cf 184=back
9c97a342 185
39c4a6cf 186=head2 Removed Modules and Pragmata
d99849ae 187
39c4a6cf 188=over 4
d99849ae 189
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190=item *
191
39c4a6cf 192XXX
ff433f2d 193
13900f93 194=back
aac7f82f 195
13900f93 196=head1 Documentation
aac7f82f 197
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198XXX Changes to files in F<pod/> go here. Consider grouping entries by
199file and be sure to link to the appropriate page, e.g. L<perlfunc>.
6d9b7c7c 200
39c4a6cf 201=head2 New Documentation
2a395b86 202
39c4a6cf 203XXX Changes which create B<new> files in F<pod/> go here.
2a395b86 204
39c4a6cf 205=head3 L<XXX>
2a395b86 206
39c4a6cf 207XXX Description of the purpose of the new file here
2a395b86 208
39c4a6cf 209=head2 Changes to Existing Documentation
2a395b86 210
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211XXX Changes which significantly change existing files in F<pod/> go here.
212However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
213section.
214
215=head3 L<XXX>
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216
217=over 4
218
219=item *
220
39c4a6cf 221XXX Description of the change here
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222
223=back
224
39c4a6cf 225=head1 Diagnostics
2a395b86 226
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227The following additions or changes have been made to diagnostic output,
228including warnings and fatal error messages. For the complete list of
229diagnostic messages, see L<perldiag>.
2a395b86 230
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231XXX New or changed warnings emitted by the core's C<C> code go here. Also
232include any changes in L<perldiag> that reconcile it to the C<C> code.
2a395b86 233
39c4a6cf 234=head2 New Diagnostics
0f4a583b 235
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236XXX Newly added diagnostic messages go under here, separated into New Errors
237and New Warnings
2a395b86 238
39c4a6cf 239=head3 New Errors
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240
241=over 4
242
243=item *
244
39c4a6cf 245XXX L<message|perldiag/"message">
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246
247=back
248
39c4a6cf 249=head3 New Warnings
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250
251=over 4
252
253=item *
254
39c4a6cf 255XXX L<message|perldiag/"message">
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256
257=back
6d9b7c7c 258
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259=head2 Changes to Existing Diagnostics
260
261XXX Changes (i.e. rewording) of diagnostic messages go here
7f55cec0 262
13900f93 263=over 4
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264
265=item *
266
39c4a6cf 267XXX Describe change here
aac7f82f 268
13900f93 269=back
aac7f82f 270
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271=head2 Diagnostic Removals
272
273=over 4
274
275=item *
276
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277"Constant is not a FOO reference"
278
279Compile-time checking of constant dereferencing (e.g.,
280C<< my_constant->() >>) has been removed, since it was not taking
281overloading into account. [perl #69456] [perl #122607]
282
283=item *
284
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285The warning "Ambiguous use of -foo resolved as -&foo()" has been removed.
286There is actually no ambiguity here, and this impedes the use of negated
287constants; e.g., C<-Inf>.
288
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289=item *
290
291The little-known C<my Class $var> syntax (see L<fields> and L<attributes>)
292could get confused in the scope of C<use utf8> if C<Class> were a constant
293whose value contained Latin-1 characters.
294
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295=back
296
39c4a6cf 297=head1 Utility Changes
091fed7c 298
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299XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
300Most of these are built within the directory F<utils>.
902c1f75 301
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302[ List utility changes as a =head2 entry for each utility and =item
303entries for each change
304Use L<XXX> with program names to get proper documentation linking. ]
2901561d 305
39c4a6cf 306=head2 L<XXX>
4594cf53 307
13900f93 308=over 4
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309
310=item *
311
39c4a6cf 312XXX
a1d26ccd 313
39c4a6cf 314=back
a1d26ccd 315
39c4a6cf 316=head1 Configuration and Compilation
7065301c 317
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318XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
319go here. Any other changes to the Perl build process should be listed here.
320However, any platform-specific changes should be listed in the
321L</Platform Support> section, instead.
58f25ac1 322
39c4a6cf 323[ List changes as a =item entry ].
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324
325=over 4
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326
327=item *
328
39c4a6cf 329XXX
a5873648 330
39c4a6cf 331=back
a5873648 332
39c4a6cf 333=head1 Testing
a5873648 334
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335XXX Any significant changes to the testing of a freshly built perl should be
336listed here. Changes which create B<new> files in F<t/> go here as do any
337large changes to the testing harness (e.g. when parallel testing was added).
338Changes to existing files in F<t/> aren't worth summarizing, although the bugs
339that they represent may be covered elsewhere.
a5873648 340
39c4a6cf 341[ List each test improvement as a =item entry ]
a5873648 342
39c4a6cf 343=over 4
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344
345=item *
346
39c4a6cf 347XXX
a5873648 348
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349=back
350
39c4a6cf 351=head1 Platform Support
b10906fb 352
39c4a6cf 353XXX Any changes to platform support should be listed in the sections below.
b10906fb 354
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355[ Within the sections, list each platform as a =item entry with specific
356changes as paragraphs below it. ]
b10906fb 357
39c4a6cf 358=head2 New Platforms
b10906fb 359
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360XXX List any platforms that this version of perl compiles on, that previous
361versions did not. These will either be enabled by new files in the F<hints/>
362directories, or new subdirectories and F<README> files at the top level of the
363source tree.
13900f93 364
7065301c 365=over 4
24a38d90 366
39c4a6cf 367=item XXX-some-platform
24a38d90 368
39c4a6cf 369XXX
bb076206 370
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371=back
372
39c4a6cf 373=head2 Discontinued Platforms
097675bf 374
39c4a6cf 375XXX List any platforms that this version of perl no longer compiles on.
b3211734 376
6e97d65d 377=over 4
b3211734 378
39c4a6cf 379=item XXX-some-platform
7065301c 380
39c4a6cf 381XXX
13900f93 382
39c4a6cf 383=back
7d0ccdba 384
39c4a6cf 385=head2 Platform-Specific Notes
7d0ccdba 386
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387XXX List any changes for specific platforms. This could include configuration
388and compilation changes or changes in portability/compatibility. However,
389changes within modules for platforms should generally be listed in the
390L</Modules and Pragmata> section.
6e97d65d 391
39c4a6cf 392=over 4
6e97d65d 393
39c4a6cf 394=item XXX-some-platform
6e97d65d 395
39c4a6cf 396XXX
7d0ccdba 397
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398=back
399
400=head1 Internal Changes
401
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402XXX Changes which affect the interface available to C<XS> code go here. Other
403significant internal changes for future core maintainers should be noted as
404well.
c9fcb674 405
39c4a6cf 406[ List each change as a =item entry ]
a835cd47 407
39c4a6cf 408=over 4
c1284011 409
7d15b1a8 410XXX
1c43698b 411
6d9b7c7c 412=back
c1284011 413
6d9b7c7c 414=head1 Selected Bug Fixes
375f5f06 415
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416XXX Important bug fixes in the core language are summarized here. Bug fixes in
417files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
418
419[ List each fix as a =item entry ]
420
0346c3a9 421=over 4
375f5f06 422
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423=item *
424
39c4a6cf 425XXX
2884baee 426
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427=item *
428
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429Constant dereferencing now works correctly for typeglob constants.
430Previously the glob was stringified and its name looked up. Now the glob
431itself is used. [perl #69456]
432
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433=item *
434
435When parsing a funny character ($ @ % &) followed by braces, the parser no
436longer tries to guess whether it is a block or a hash constructor (causing
437a syntax error when it guesses the latter), since it can only be a block.
438
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439=item *
440
441C<undef $reference> now frees the referent immediately, instead of hanging
442on to it until the next statement. [perl #122556]
443
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444=item *
445
446Various cases where the name of a sub is used (autoload, overloading, error
447messages) used to crash for lexical subs, but have been fixed.
448
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449=item *
450
451Bareword lookup now tries to avoid vivifying packages if it turns out the
452bareword is not going to be a subroutine name.
453
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454=item *
455
456Compilation of anonymous constants (e.g., C<sub () { 3 }>) no longer
457deletes any subroutine named C<__ANON__> in the current package. Not only
458was C<*__ANON__{CODE}> cleared, but there was a memory leak, too. This bug
459goes back to perl 5.8.0.
460
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461=item *
462
463Stub declarations like C<sub f;> and C<sub f ();> no longer wipe out
464constants of the same name declared by C<use constant>. This bug was
465introduced in perl 5.10.0.
466
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467=item *
468
469Under some conditions a warning raised in compilation of regular
470expression patterns could be displayed multiple times. This is now
471fixed.
472
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473=item *
474
475C<qr/[\N{named sequence}]/> now works properly in many instances. Some
476names known to C<\N{...}> refer to a sequence of multiple characters,
477instead of the usual single character. Bracketed character classes
478generally only match single characters, but now special handling has
479been added so that they can match named sequences, but not if the class
480is inverted or the sequence is specified as the beginning or end of a
481range. In these cases, the only behavior change from before is a slight
482rewording of the fatal error message given when this class is part of a
483C<?[...])> construct. When the C<[...]> stands alone, the same
484non-fatal warning as before is raised, and only the first character in
485the sequence is used, again just as before.
486
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487=item *
488
489Tainted constants evaluated at compile time no longer cause unrelated
490statements to become tainted. [perl #122669]
491
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492=item *
493
494C<open $$fh, ...>, which vivifies a handle with a name like "main::_GEN_0",
495was not giving the handle the right reference count, so a double free could
496happen.
497
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498=item *
499
500When deciding that a bareword was a method name, the parser would get
501confused if an "our" sub with the same name existed, and look up the method
502in the package of the "our" sub, instead of the package of the invocant.
503
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504=item *
505
506The parser no longer gets confused by C<\U=> within a double-quoted string.
507It used to roduce a syntax error, but now compiles it correctly.
508[perl #80368]
509
39c4a6cf 510=back
b756670b 511
39c4a6cf 512=head1 Known Problems
b756670b 513
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514XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
515tests that had to be C<TODO>ed for the release would be noted here. Unfixed
516platform specific bugs also go here.
e917e94e 517
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518[ List each fix as a =item entry ]
519
520=over 4
e917e94e 521
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522=item *
523
39c4a6cf 524XXX
26dd5fd6 525
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526=back
527
39c4a6cf 528=head1 Errata From Previous Releases
e831f11a 529
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530=over 4
531
532=item *
ff433f2d 533
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534XXX Add anything here that we forgot to add, or were mistaken about, in
535the perldelta of a previous release.
ff433f2d 536
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537=back
538
539=head1 Obituary
ff433f2d 540
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541XXX If any significant core contributor has died, we've added a short obituary
542here.
ff433f2d 543
39c4a6cf 544=head1 Acknowledgements
ff433f2d 545
39c4a6cf 546XXX Generate this with:
e831f11a 547
39c4a6cf 548 perl Porting/acknowledgements.pl v5.21.3..HEAD
f5b73711 549
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550=head1 Reporting Bugs
551
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552If you find what you think is a bug, you might check the articles recently
553posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 554https://rt.perl.org/ . There may also be information at
7ef8b31d 555http://www.perl.org/ , the Perl Home Page.
44691e6f 556
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557If you believe you have an unreported bug, please run the L<perlbug> program
558included with your release. Be sure to trim your bug down to a tiny but
559sufficient test case. Your bug report, along with the output of C<perl -V>,
560will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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561
562If the bug you are reporting has security implications, which make it
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563inappropriate to send to a publicly archived mailing list, then please send it
564to perl5-security-report@perl.org. This points to a closed subscription
565unarchived mailing list, which includes all the core committers, who will be
566able to help assess the impact of issues, figure out a resolution, and help
f9001595 567co-ordinate the release of patches to mitigate or fix the problem across all
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568platforms on which Perl is supported. Please only use this address for
569security issues in the Perl core, not for modules independently distributed on
570CPAN.
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571
572=head1 SEE ALSO
573
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574The F<Changes> file for an explanation of how to view exhaustive details on
575what changed.
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576
577The F<INSTALL> file for how to build Perl.
578
579The F<README> file for general stuff.
580
581The F<Artistic> and F<Copying> files for copyright information.
582
583=cut