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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
129=item *
130
131L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280219.
132[perl #122675].
133
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134=item *
135
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136L<ExtUtils::Manifest> has been upgraded from version 1.65 to 1.66.
137[perl #122415].
138
139=item *
140
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141L<File::Find> has been upgraded from version 1.27 to 1.28.
142
143C<find()> and C<finddepth()> will now warn if passed inappropriate or
144misspelled options.
145
146=item *
147
148L<Getopt::Std> has been upgraded from version 1.10 to 1.11.
149
150=item *
151
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152L<HTTP::Tiny> has been upgraded from version 0.047 to 0.048.
153
154=item *
155
156L<Module::CoreList> has been upgraded from version 5.021003 to 5.021004.
157
158=item *
159
160L<POSIX> has been upgraded from version 1.42 to 1.43.
161
162=item *
163
164L<Pod::Perldoc> has been upgraded from version 3.23 to 3.24.
165
166=item *
167
168L<constant> has been upgraded from version 1.31 to 1.32.
169
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170It now accepts fully-qualified constant names, allowing constants to be
171defined in packages other than the caller.
172
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173=item *
174
175L<threads> has been upgraded from version 1.95 to 1.96.
176
39c4a6cf 177=back
9c97a342 178
39c4a6cf 179=head2 Removed Modules and Pragmata
d99849ae 180
39c4a6cf 181=over 4
d99849ae 182
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183=item *
184
39c4a6cf 185XXX
ff433f2d 186
13900f93 187=back
aac7f82f 188
13900f93 189=head1 Documentation
aac7f82f 190
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191XXX Changes to files in F<pod/> go here. Consider grouping entries by
192file and be sure to link to the appropriate page, e.g. L<perlfunc>.
6d9b7c7c 193
39c4a6cf 194=head2 New Documentation
2a395b86 195
39c4a6cf 196XXX Changes which create B<new> files in F<pod/> go here.
2a395b86 197
39c4a6cf 198=head3 L<XXX>
2a395b86 199
39c4a6cf 200XXX Description of the purpose of the new file here
2a395b86 201
39c4a6cf 202=head2 Changes to Existing Documentation
2a395b86 203
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204XXX Changes which significantly change existing files in F<pod/> go here.
205However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
206section.
207
208=head3 L<XXX>
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209
210=over 4
211
212=item *
213
39c4a6cf 214XXX Description of the change here
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215
216=back
217
39c4a6cf 218=head1 Diagnostics
2a395b86 219
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220The following additions or changes have been made to diagnostic output,
221including warnings and fatal error messages. For the complete list of
222diagnostic messages, see L<perldiag>.
2a395b86 223
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224XXX New or changed warnings emitted by the core's C<C> code go here. Also
225include any changes in L<perldiag> that reconcile it to the C<C> code.
2a395b86 226
39c4a6cf 227=head2 New Diagnostics
0f4a583b 228
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229XXX Newly added diagnostic messages go under here, separated into New Errors
230and New Warnings
2a395b86 231
39c4a6cf 232=head3 New Errors
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233
234=over 4
235
236=item *
237
39c4a6cf 238XXX L<message|perldiag/"message">
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239
240=back
241
39c4a6cf 242=head3 New Warnings
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243
244=over 4
245
246=item *
247
39c4a6cf 248XXX L<message|perldiag/"message">
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249
250=back
6d9b7c7c 251
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252=head2 Changes to Existing Diagnostics
253
254XXX Changes (i.e. rewording) of diagnostic messages go here
7f55cec0 255
13900f93 256=over 4
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257
258=item *
259
39c4a6cf 260XXX Describe change here
aac7f82f 261
13900f93 262=back
aac7f82f 263
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264=head2 Diagnostic Removals
265
266=over 4
267
268=item *
269
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270"Constant is not a FOO reference"
271
272Compile-time checking of constant dereferencing (e.g.,
273C<< my_constant->() >>) has been removed, since it was not taking
274overloading into account. [perl #69456] [perl #122607]
275
276=item *
277
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278The warning "Ambiguous use of -foo resolved as -&foo()" has been removed.
279There is actually no ambiguity here, and this impedes the use of negated
280constants; e.g., C<-Inf>.
281
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282=item *
283
284The little-known C<my Class $var> syntax (see L<fields> and L<attributes>)
285could get confused in the scope of C<use utf8> if C<Class> were a constant
286whose value contained Latin-1 characters.
287
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288=back
289
39c4a6cf 290=head1 Utility Changes
091fed7c 291
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292XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
293Most of these are built within the directory F<utils>.
902c1f75 294
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295[ List utility changes as a =head2 entry for each utility and =item
296entries for each change
297Use L<XXX> with program names to get proper documentation linking. ]
2901561d 298
39c4a6cf 299=head2 L<XXX>
4594cf53 300
13900f93 301=over 4
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302
303=item *
304
39c4a6cf 305XXX
a1d26ccd 306
39c4a6cf 307=back
a1d26ccd 308
39c4a6cf 309=head1 Configuration and Compilation
7065301c 310
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311XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
312go here. Any other changes to the Perl build process should be listed here.
313However, any platform-specific changes should be listed in the
314L</Platform Support> section, instead.
58f25ac1 315
39c4a6cf 316[ List changes as a =item entry ].
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317
318=over 4
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319
320=item *
321
39c4a6cf 322XXX
a5873648 323
39c4a6cf 324=back
a5873648 325
39c4a6cf 326=head1 Testing
a5873648 327
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328XXX Any significant changes to the testing of a freshly built perl should be
329listed here. Changes which create B<new> files in F<t/> go here as do any
330large changes to the testing harness (e.g. when parallel testing was added).
331Changes to existing files in F<t/> aren't worth summarizing, although the bugs
332that they represent may be covered elsewhere.
a5873648 333
39c4a6cf 334[ List each test improvement as a =item entry ]
a5873648 335
39c4a6cf 336=over 4
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337
338=item *
339
39c4a6cf 340XXX
a5873648 341
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342=back
343
39c4a6cf 344=head1 Platform Support
b10906fb 345
39c4a6cf 346XXX Any changes to platform support should be listed in the sections below.
b10906fb 347
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348[ Within the sections, list each platform as a =item entry with specific
349changes as paragraphs below it. ]
b10906fb 350
39c4a6cf 351=head2 New Platforms
b10906fb 352
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353XXX List any platforms that this version of perl compiles on, that previous
354versions did not. These will either be enabled by new files in the F<hints/>
355directories, or new subdirectories and F<README> files at the top level of the
356source tree.
13900f93 357
7065301c 358=over 4
24a38d90 359
39c4a6cf 360=item XXX-some-platform
24a38d90 361
39c4a6cf 362XXX
bb076206 363
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364=back
365
39c4a6cf 366=head2 Discontinued Platforms
097675bf 367
39c4a6cf 368XXX List any platforms that this version of perl no longer compiles on.
b3211734 369
6e97d65d 370=over 4
b3211734 371
39c4a6cf 372=item XXX-some-platform
7065301c 373
39c4a6cf 374XXX
13900f93 375
39c4a6cf 376=back
7d0ccdba 377
39c4a6cf 378=head2 Platform-Specific Notes
7d0ccdba 379
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380XXX List any changes for specific platforms. This could include configuration
381and compilation changes or changes in portability/compatibility. However,
382changes within modules for platforms should generally be listed in the
383L</Modules and Pragmata> section.
6e97d65d 384
39c4a6cf 385=over 4
6e97d65d 386
39c4a6cf 387=item XXX-some-platform
6e97d65d 388
39c4a6cf 389XXX
7d0ccdba 390
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391=back
392
393=head1 Internal Changes
394
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395XXX Changes which affect the interface available to C<XS> code go here. Other
396significant internal changes for future core maintainers should be noted as
397well.
c9fcb674 398
39c4a6cf 399[ List each change as a =item entry ]
a835cd47 400
39c4a6cf 401=over 4
c1284011 402
7d15b1a8 403XXX
1c43698b 404
6d9b7c7c 405=back
c1284011 406
6d9b7c7c 407=head1 Selected Bug Fixes
375f5f06 408
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409XXX Important bug fixes in the core language are summarized here. Bug fixes in
410files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
411
412[ List each fix as a =item entry ]
413
0346c3a9 414=over 4
375f5f06 415
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416=item *
417
39c4a6cf 418XXX
2884baee 419
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420=item *
421
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422Constant dereferencing now works correctly for typeglob constants.
423Previously the glob was stringified and its name looked up. Now the glob
424itself is used. [perl #69456]
425
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426=item *
427
428When parsing a funny character ($ @ % &) followed by braces, the parser no
429longer tries to guess whether it is a block or a hash constructor (causing
430a syntax error when it guesses the latter), since it can only be a block.
431
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432=item *
433
434C<undef $reference> now frees the referent immediately, instead of hanging
435on to it until the next statement. [perl #122556]
436
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437=item *
438
439Various cases where the name of a sub is used (autoload, overloading, error
440messages) used to crash for lexical subs, but have been fixed.
441
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442=item *
443
444Bareword lookup now tries to avoid vivifying packages if it turns out the
445bareword is not going to be a subroutine name.
446
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447=item *
448
449Compilation of anonymous constants (e.g., C<sub () { 3 }>) no longer
450deletes any subroutine named C<__ANON__> in the current package. Not only
451was C<*__ANON__{CODE}> cleared, but there was a memory leak, too. This bug
452goes back to perl 5.8.0.
453
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454=item *
455
456Stub declarations like C<sub f;> and C<sub f ();> no longer wipe out
457constants of the same name declared by C<use constant>. This bug was
458introduced in perl 5.10.0.
459
499333dc
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460=item *
461
462Under some conditions a warning raised in compilation of regular
463expression patterns could be displayed multiple times. This is now
464fixed.
465
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466=item *
467
468C<qr/[\N{named sequence}]/> now works properly in many instances. Some
469names known to C<\N{...}> refer to a sequence of multiple characters,
470instead of the usual single character. Bracketed character classes
471generally only match single characters, but now special handling has
472been added so that they can match named sequences, but not if the class
473is inverted or the sequence is specified as the beginning or end of a
474range. In these cases, the only behavior change from before is a slight
475rewording of the fatal error message given when this class is part of a
476C<?[...])> construct. When the C<[...]> stands alone, the same
477non-fatal warning as before is raised, and only the first character in
478the sequence is used, again just as before.
479
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480=item *
481
482Tainted constants evaluated at compile time no longer cause unrelated
483statements to become tainted. [perl #122669]
484
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485=item *
486
487C<open $$fh, ...>, which vivifies a handle with a name like "main::_GEN_0",
488was not giving the handle the right reference count, so a double free could
489happen.
490
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491=item *
492
493When deciding that a bareword was a method name, the parser would get
494confused if an "our" sub with the same name existed, and look up the method
495in the package of the "our" sub, instead of the package of the invocant.
496
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497=item *
498
499The parser no longer gets confused by C<\U=> within a double-quoted string.
500It used to roduce a syntax error, but now compiles it correctly.
501[perl #80368]
502
39c4a6cf 503=back
b756670b 504
39c4a6cf 505=head1 Known Problems
b756670b 506
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507XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
508tests that had to be C<TODO>ed for the release would be noted here. Unfixed
509platform specific bugs also go here.
e917e94e 510
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511[ List each fix as a =item entry ]
512
513=over 4
e917e94e 514
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515=item *
516
39c4a6cf 517XXX
26dd5fd6 518
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519=back
520
39c4a6cf 521=head1 Errata From Previous Releases
e831f11a 522
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523=over 4
524
525=item *
ff433f2d 526
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527XXX Add anything here that we forgot to add, or were mistaken about, in
528the perldelta of a previous release.
ff433f2d 529
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530=back
531
532=head1 Obituary
ff433f2d 533
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534XXX If any significant core contributor has died, we've added a short obituary
535here.
ff433f2d 536
39c4a6cf 537=head1 Acknowledgements
ff433f2d 538
39c4a6cf 539XXX Generate this with:
e831f11a 540
39c4a6cf 541 perl Porting/acknowledgements.pl v5.21.3..HEAD
f5b73711 542
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543=head1 Reporting Bugs
544
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545If you find what you think is a bug, you might check the articles recently
546posted to the comp.lang.perl.misc newsgroup and the perl bug database at
238894db 547https://rt.perl.org/ . There may also be information at
7ef8b31d 548http://www.perl.org/ , the Perl Home Page.
44691e6f 549
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550If you believe you have an unreported bug, please run the L<perlbug> program
551included with your release. Be sure to trim your bug down to a tiny but
552sufficient test case. Your bug report, along with the output of C<perl -V>,
553will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
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554
555If the bug you are reporting has security implications, which make it
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556inappropriate to send to a publicly archived mailing list, then please send it
557to perl5-security-report@perl.org. This points to a closed subscription
558unarchived mailing list, which includes all the core committers, who will be
559able to help assess the impact of issues, figure out a resolution, and help
f9001595 560co-ordinate the release of patches to mitigate or fix the problem across all
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561platforms on which Perl is supported. Please only use this address for
562security issues in the Perl core, not for modules independently distributed on
563CPAN.
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564
565=head1 SEE ALSO
566
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567The F<Changes> file for an explanation of how to view exhaustive details on
568what changed.
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569
570The F<INSTALL> file for how to build Perl.
571
572The F<README> file for general stuff.
573
574The F<Artistic> and F<Copying> files for copyright information.
575
576=cut